A The number of elements in the anal fin, often comprising spines (Roman numerals) and soft rays (Arabic numerals).
abyssal at or near the deepsea floor, usually below 2000 m
AC The ventral series of photophores behind the anal-fin origin
ACA the first part of the ventral series of photophores behind the anal-fin origin
ACB Second part of the ventral series of photophores behind the anal-fin origin
ACC the third section in ventral series of photophores posterior to the anal-fin origin
accessory lateral line a branch of the lateral line following the dorsal outline of the body just below the dorsal-fin base
actiniarians sea anemones; short, broad tubular invertebrates usually attached to rocky substrates at the base, with the free end encircled by tentacles; members of the cnidarian class Anthozoa and order Actiniaria.
adherent not easily dislodged; firmly attached; non-deciduous
adipose fatty or fleshy tissue
adipose eyelid a thick, mostly transparent tissue that partly or wholly covers the eye
adipose fin a small fleshy fin, without fin rays, usually situated behind the dorsal or anal fins
adnate joined together
adpressed pressed against the body.
adult sexually mature.
aestivate spend periods of drought in a torpid state, usually in summer, or during long periods of dryness.
aggregate group together.
alar wing-like shape, often referring to the region of the pectoral fins or the central portions of the fused pectorals and head in rays.
ammocoete filter-feeding freshwater larval stage of lampreys with reduced eyes.
amphibians primitive vertebrates, including frogs and salamanders, living in water and on land.
Amphidromous fishes which migrate between fresh water and the sea (or vice versa) at some stage in their life cycle.
amphipod a sand hopper; a small crustacean of the order Amphipoda usually with a compressed shrimp-like body.
amphitemperate occurring in temperate environments in both the Northern and Southern Hemispheres.
Anadromy a widespread migratory life history in fishes where spawning occurs in fresh water and individuals migrate to the sea as juveniles and adults
anal fin the unpaired fin situated on the lower surface of the body behind the anus.
anal ring in the Syngnathidae, last trunk ring bearing the anus.
anal spine a spine at the origin of the anal fin before the soft rays.
Ant light organ anterodorsal to eye.
anterior(ly) (adj. anteriormost comb. antero) relating to the front or head end of the body
anterolateral: to the front and side.| anteroposterior from the front end to the rear end.
anti-equatorial away from the equator in both the Northern and Southern Hemispheres.
Antipodean relating to the region of Australia and New Zealand.
antitropical those parts of the tropics away from the equator in the Northern and Southern Hemispheres.
anus (adj. anal) external opening of the digestive system for expelling body wastes
AO ventral series of photophores comprising AOa + AOp.
AOa ventral series of photophores above anal fin.
AOp ventral series of photophores just posterior to anal fin.
AOP preorbital light organ anteroventral to eye.
apex (pl. apices) the tip or end.
AR anal ring.
armoured having an armour-like, rigid and often jointed protective external covering.
articulate (ing) united by a movable joint.
ascidian a sea squirt; a soft, leathery-bodied invertebrate of the tunicate class Ascidiacea (chordates), often resembling simple barrel-shaped sponges.
aspect view.
assemblage grouping, often in a relationship sense (eg a group of organisms sharing a common ancestor).
asymmetrical not symmetrical.
atriopore the rear opening to the atrium or cavity, through which water is circulated in lancelets
attenuate slender.
auditory pertaining to hearing.
austral southern.
axial muscles muscles in the axis of the body (running from the front end to the rear end).
axil, axilla the angle formed by the inner edge of a fin and the body at the point of attachment of the fin to the body
axillary process a small scale-like or fleshy projection at the axil of the pectoral or ventral fins
axillary tissue epidermal, and sometimes dermal, scale-like feature on the posterior side of the pectoral- or ventral-fin base.
axis imaginary line around which a body or structure is symmetrically arranged.
ballast water water taken in by a vessel to provide stability when operating in the open ocean, usually held within tanks constructed low in the hull for that purpose.
band (adj. banded) vertical strip of colour.
bar band.
barb (adj. barbed) secondary backward-projecting point, as on a fish hook; also a serrated, spear-like, structure, as on the tail of some rays
barbel a fleshy, tentacle-like structure on the head (often near the mouth) of some fishes
basal(ly) at or near the base.
basibranchial one of several median cartilaginous or bony structures in the branchial arch behind the tongue.
basketwork arranged in a cross-hatch pattern, resembling the pattern of a wicker basket.
bathyal pertaining to or living on the sea floor at a depth range of 200-4000 metres, on the continental slope and rise.
bathydemersal Living and feeding on the bottom below 200 m
bathypelagic free swimming in ocean depths of 1000 to 4000m, but not close to the bottom.
batteries cellular structure capable of supplying electrical discharges.
beak horny projecting jaws, as in birds.
benthic living on the sea floor.
benthopelagic free swimming near the sea floor.
BI section of the lateral line canal from behind the head to the base of the tail.
bicuspid referring to a tooth with two cusps or points.
bifid bifurcate divided into two parts.
bilateral on both sides.
bill slender, sword-like anterior extension of either the upper or lower jaw.
bilobed bilobate having two lobes.
binomial having two names, or parts to a name.
biogeographical relating to distributions determined by historical events and biological tolerances of organisms.
bioluminescence (adj. bioluminescent) light produced chemically by living organisms, including fishes, where chemical energy is transformed into light energy.
biomass total quantity or weight of organisms in a given area.
biotone area of overlap between adjacent natural ranges of geographical distribution or 'provinces' around the continent
biserial occurring in two regular series.
BL body length.
blind side the side of body in flatfishes without eyes - the underside.
body depth maximum vertical distance between the dorsal and ventral profiles of the body unless a specific location is provided (eg. 'at dorsal-fin origin').
body length overall length of a fish expressed as 'fork length', 'standard length', 'total length', or as in the billfishes, 'body length' (direct measurement from the anterior tip of lower jaw to hind margin of caudal fin at its centre
Br 3 photophores on branchiostegal membranes.
BR series of photophores on branchiostegal membranes.
branched ray a soft fin-ray that is divided into two or more parts at its free (unattached) end.
branchial pertaining to the gills.
branchial length distance from the front of the first to the front of the last gill aperture.
branchial slime pores slime pores in immediate association with the gill aperture or apertures.
branchiostegal ray each of the bony rays supporting the gill (branchiostegal) membranes behind the lower jaw.
breast area of the body below the pectoral fins.
brood pouch pouch in the body where eggs are deposited and held until hatching.
bryozoan primitive colonial invertebrate with a calcareous skeleton, often resembling an encrustation, or a three-dimensional structure resembling coral.
buccal inside of the mouth.
buckler bony plate or plates, sometimes bearing spines, on the bodies of some fishes.
bulbous swollen or rounded in shape.
bycatch non-commercial component of fisheries' catch.
C number of principal fin rays in the caudal fin, frequently equalling the number of branched rays + 2.
caecum (pl. caecae) see 'pyloric caecum'.
canine tooth a long conical tooth in the mouth, adapted for grasping prey.
caniniform having the form of canine teeth.
capsule surrounding envelope, often protective.
carapace rigid covering encasing the body.
cartilage (adj. cartilaginous) soft and flexible gristle-like material that helps to provide structural support for the body.
caruncle fleshy outgrowth.
Catadromy A type of migration where fish spawn in marine habitats and migrate to freshwater as juveniles and adults.
catchment series of more or less interconnected creeks, streams and rivers draining a geographical area.
caudal referring to the tail region.
caudal filament slender prolongation of caudal-fin ray or membrane.
caudal fin tail fin.
caudal peduncle part of the body between the end of the anal fin base and the base of the caudal fin.
caudal peduncle depth least vertical distance between the upper and lower profiles of the caudal peduncle.
caudal peduncle length oblique distance between the base of the last anal-fin ray and the hind end of the hypural plates.
caudal vertebra(e) those vertebrae in the vertebral column, posterior to the abdominal cavity, which possess a haemal spine (at least on the anteriormost).
Caulerpa green macroalgae, often with fleshy 'leafs' in a variety of forms.
Ce photophore above posterior edge of preopercle.
cephalic lateralis canal portion of the laterosensory system on the head, partially surrounded in some areas by superficial elements of the skull.
cephalopod cuttlefish, octopus and squid; representatives of the specialised mollusc class Cephalopoda.
cheek area between the eye and the free edge of the preopercular bone.
chevron-shaped having the shape of a bent bar or inverted V.
chitin (adj. chitinous) horny exoskeleton, like that of insects and crustaceans.
Chordate Animals, either vertebrates, hagfish or several closely-related invertebrates – all with a notochord, a hollow dorsal nerve cord, gill slits in the pharynx and a tail at some stage during their life cycle.
ciliate having many fine hair-like structures.
circumglobal around the world.
circumnarial groove groove around the nostrils.
circumorbital pertaining to the region immediately encircling each eye, especially the series of bones forming the bony orbital rim and enclosing a portion of the laterosensory canal.
circumtropical around the world at tropical latitudes.
cirrus (pl. cirri) small, thin, tentacle-like or flap-like appendage that may be subdivided into branches.
CITES The Convention on International Trade in Endangered Species of Wild Fauna and Flora
clade natural grouping containing all descendants of a common ancestor.
clasper specialised structures of male cartilaginous fishes that facilitate breeding, most frequently referring to the tubular modified part of each ventral fin,used to transmit sperm during copulation.
clavus rudder-like structure replacing the caudal fin at the posterior end of the body in sunfishes (Molidae).
cleithral spine spine at the dorsal end of the cleithrum, usually prominent when present and directed posteriorly.
cleithrum major bone providing the basal support for the pectoral girdle and fin.
cloaca common opening to the exterior for the digestive, reproductive and urinary tracts in some fishes.
cm centimetre(s).
CO circumorbital pores.
cockscomb crest on the head of a male chicken.
colonial aggregate, connected or living together in close proximity.
commensal referring to an organism that lives with or on another but neither at the expense of the other; living in a mutually beneficial relationship.
complete in entirety, uninterrupted.
compressed flattened from side to side.
confluent joined together, continuous.
congener belonging to the same genus.
conical cone-shaped.
contiguous adjoining; next in order.
continental shelf gently sloping sea bed extending from the shore to a depth of about 200m.
continental slope rather steeply sloping sea bed extending from the outer margin of the continental shelf to a depth of about 2000m.
continuous unbroken; often a fin or lateral line that is not divided into two or more parts.
convergent evolution of similar characters in unrelated taxonomic groups, eg fin-like structures in fishes and whales.
co-occur occur together.
copepod small, often tiny crustaceans of the subclass Copepoda having a wide variety of body shapes.
copulatory associated with the physical act of reproduction of male and female.
coronal pore cephalic sensory canal pore on the dorsal midline of the head at the centre of the coronal commissure joining the canals dorsoposteriorly on either side above the eyes.
coronal spine spine(s) above and behind the eyes at the anterior edge of the occipital pit, originating from the posterior ends of the interorbital ridges.
corselet band of specialised scales encircling the pectoral region of the body.
cosmopolitan occurring everywhere.
countershading colour pattern of fishes in the water column that are dark-coloured on top but light-coloured on the bottom, effectively to obscure the outline of the fish to predators by blending with the dark sea floor when viewed from above and the light sky when viewed from below.
couplet pair of contrasting statements presented in identification keys that assists the reader in reaching an identification.
cranial cranium portion of the skull enclosing the brain; neurocranium.
craniate group including all animals with a cranium (a cartilaginous or bony skull) enclosing a well-developed brain.
crenulate with the margin in the shape of small, rounded notches.
crescent-shaped shaped like the moon in the first or last quarter.
crest elevated ridge, especially on a bone surface.
cross band band of colour, usually fully traversing the structure.
crossbar cross band.
cross-section transverse section.
crown top part, especially the head; in the form of a monarch's crown.
crumenal organ small pouch-like structure behind the fourth gill arch in which gill rakers from both sides interdigitate for breaking up food particles.
crustacean(s) each of a group of invertebrate animals that have external skeletons with jointed appendages; includes crabs, prawns, crayfish, etc.
cryptic camouflaged; well hidden.
cteni minute spines.
ctenoid (scale) scale in which the hind margin and often the exposed lateral surface bears minute spines, giving the body a rough feeling.
ctenophores comb jellies; free-swimming invertebrates of the small phylum Ctenophora, usually with a clear gelatinous body somewhat resembling jelly fish (medusoid coelenterates).
cunjevoi sea squirt, attached invertebrate (ascidian) resembling a leathery sponge.
cusp small point or projection on a tooth.
cusplet small cusp, often at the base of a larger central cusp.
cutaneous folds skin folds or ridges.
cycloid (scale) scale in which the hind margin and exposed lateral surface is smooth.
D number of elements in the dorsal fin, often comprising spines (Roman numerals) and soft rays (Arabic numerals).
deciduous easily shed or rubbed off.
deepsea away from inshore and surface waters, usually at depths with little or no light from the sky.
degenerate said of a character or structure that has evolved from an advanced state to a less developed state.
demersal living on or in association with the bottom of the sea.
dendritic organ brush-like external organ adjacent to the anus in eeltail catfishes (Plotosidae), which is thought to have a salt-regulating function.
dentary largest and most anterior of the bones on each side of the lower jaw, on which teeth are based.
denticle tooth-like scale found on the bodies of sharks and rays.
denticulation denticulate (adj. denticular) small tooth-like sculpturing.
dentition teeth in the mouth.
depressed flattened from top to bottom.
depressible not fixed in an erect manner, capable of being rotated or bent down.
dermal pertaining to the skin.
dermal flap small skin flap.
dermal tentacle fleshy outgrowth of the skin.
detritus (adj. detrital) debris; broken, often abraded material, most frequently organic.
diagnosis brief summary of characteristics that define a natural group (eg species, genus, family).
diagonal scale rows oblique scale rows; regular arrangement of scales in slanted rows along the side of a fish's body usually counted above the lateral line, if present, from the edge of the operculum to the hypural edge.
dichotomous key identification aid organised as a sequential series of contrasting statements (couplets) pertaining to morphological structures and appearances present in the organism in question.
dichromatic having two different colour forms.
Diel vertical migration (DVM) a behaviour often documented in pelagic oceanic or lake-dwelling fishes, where individuals migrate from the deep waters to the epipelagic waters - usually at night
dimorphic, dimorphism having two forms
disc fused head, trunk and paired fins of some fishes, particularly sharks, skates and rays.
disjunct not continuous, interrupted.
dispersal moving outwards, frequently away from the place of origin.
distal remote from the point of attachment.
distensible capable of projecting or swelling outwards.
diurnally of the daylight hours.
divergent diverging proceeding in different directions.
diverticula (in relation to pyloric caeca) an outpocketing or blind-ending tube from a cavity or blind sac.
Dn light organ above nostril.
DNA deoxyribonucleic acid, the blueprint of life in body cells.
dorsad in a dorsal direction.
dorsal fin unpaired fin extending along the midline of the back.
dorsal(ly) (comb. dorso-) adj. relating to the upper surface or back.
dorsal-fin chambers series of lymph compartments within the finfold surrounding the notochord on the dorsal side of the body.
dorsolateral between the back and the middle of the side, the upper area of the side.
dorsoventral(ly) stretching from the dorsal to the ventral surfaces.
dorsum upper (dorsal) surface of the head or body.
drop-off place of rapid increase in depth, like an underwater cliff face.
drumming making low pitched beating sound.
duct channel or tube for conveying a substance.
DW disc width.
Ecklonia macrophytic brown seaweed with fluted leathery fronds.
ectopterygoid bone forming a forward part of the suspensorium, the ventral edge usually positioned laterally on the roof of the mouth and sometimes bearing teeth.
eddies whirlpools, especially at the periphery of a major current.
eelgrass <em>Zostera</em>, a marine green plant with long slender leaves.
efferent branchial duct tube-like connection from the gill chamber to the gill opening to the exterior.
elasmobranch pertaining to sharks and rays.
electric organ structure capable of emitting electrical discharges through the surrounding water and which may be used to stun prey, to repel predators or as a radar-like device to detect objects under conditions of poor visibility.
electrosensory capable of detecting electrical discharges.
elliptical relating to an oval shape.
elongated extended or drawn out.
elver fully pigmented immature eel, resembling a small version of an adult.
emarginate having a slightly concave, indented or forked margin or edge.
embayment body of water enclosed into a bay.
embedded (scales spine) completely covered with skin.
embryo (adj. embryonic) offspring prior to birth.
encapsulate enclose in a capsule.
encyst enclose in a bladder-like sac.
endemic occurring naturally only in a specific area.
endoskeleton internal skeleton.
ephemeral lasting for a markedly brief time.
epidermis (adj. epidermal) outer surface layer of skin.
epipelagic free swimming in the upper part of the open ocean from the surface to a depth of about 200m.
erectile capable of being raised, as in the spines of some fishes.
esca (adj. escal) lure or 'bait' on the end of the rod-like dorsal head appendage (illicium) of some anglerfishes and their relatives.
estuary (adj. estuarine) portion of a river where it meets the sea and fresh and salt waters mingle or alternate.
euphausid krill; shrimp-like crustacean that feeds on phytoplankton and often occurs in huge numbers.
euryhaline the ability to live in a wide range of water salinity.
evert(ed) turned outward or inside out.
exoskeleton external skeleton.
extralimital occurring outside one's normal distribution.
extremity very end.
eye diameter maximum diameter of the eye, frequently measured in a horizontal direction.
eyed side the side of the body in adult flatfishes on which both eyes are located.
eyeshine seemingly iridescent reflection of light in nocturnally active animals that have a special reflective layer associated with the retina.
falcate curved or sickle-shaped.
fang very elongated, slender canine.
fertilisation fusion of the male and female reproductive cells.
filament (adj. filamentous) thread-like.
filter-feeder fish that obtains small particles of food (plankton) by filtering them out of the water, usually with numerous elongated and fine gill rakers.
fimbriate(d) with the margin fringed, bordered with hairs.
fin structure on the fish's body used for propelling or steering.
fin ray bilaterally paired supporting element of a fin that is often flexible, segmented and branched.
finfold ridge on the body that is a precursor of, a remnant of, or a continuation of a fin.
fingerling young or small fish.
finlet small fin supported by a ray or rays, situated behind the dorsal and anal fins.
fisher one who catches fish.
fixed immovable.
FL fork length.
flake marketing name for cartilaginous fish, primarily sharks.
flange projecting flat rim or edge, for strengthening or attachment.
flank fleshy part of the side of the body between the ribs and the caudal peduncle.
flats bottom with broad level surface at shallow depth.
flattened teeth compressed teeth; incisors.
flexed bent.
flexure curved, bent state.
flotsam floating wreckage.
fluorescent producing visible or invisible radiation.
fork length length of a fish measured from the tip of the snout to the fork of the caudal fin.
forked bifurcated, with diverging corners, the margin between concave to V-shaped.
fossa shallow depression or cavity.
frill ornamental edging.
fringe ornamental boarder of thread-like skin.
frontal bones pair of bones forming the roof of the brain case anteriorly.
furrow groove, long indentation.
fused joined together as one.
fusiform spindle-shaped; tapering towards each end.
gape widely open mouth.
genital papilla(e) small tube-like structure, situated behind the anus, from which sperm or eggs are released.
gestation period of embryonic development between conception and birth.
gill respiratory organ in fishes.
gill aperture gill opening.
gill arch bony or cartilaginous arch supporting the gills and gill rakers.
gill cover bony flap covering the gill chamber; the operculum.
gill membrane skin on each side of the head, supported by branchiostegal rays, which is periodically drawn across the lower portion of the gill opening to enclose the gill chamber during respiration.
gill opening opening behind the head from the gill chamber to the exterior.
gill raker one of a number of bony finger-like structures on the anterior edges of the gill arches, for the straining of food or protection of gills; may range from tooth-like bumps to thread-like stiff filaments; rakers usually arranged in parallel inner (mesial) and outer (lateral) rows, the numbers in the lateral row of the anteriormost gill arch reported in descriptions unless otherwise stated.
gill raker rudiment very short gill raker whose length is shorter than its width.
gill slit gill opening; usually paired and positioned laterally or ventrally on the head.
gillnet fishing net with mesh large enough that fish can push their head through the opening, but not their body, allowing them to be entangled by their gill covers.
girdle see 'pectoral girdle' and 'pelvic girdle'
glass eel juvenile eel with the shape of the adult, but not the pigmentation, remaining mostly transparent.
gnathostome referring to the group of fishes having jaws.
gonad reproductive organ (ovary or testes).
GR number of gill rakers on the anterior face of the 1st gill arch, often presented as rakers on upper limb + rakers on lower limb, including raker at angle.
granular (granulation) having the structure or surface of fine hard particles, eg. sand paper.
gravid sexually ripe.
gular pertaining to the region between the chin and isthmus.
gular plate bony plate below the chin and between the sides of the lower jaw.
gut lower alimentary tract, intestine.
haemal spine ventrally directed spine on each caudal vertebra bridging the caudal artery and vein at its base.
Haemoglobin An iron-containing compound found in the red blood cells of vertebrates (except the Family Channichthyidae), which transports oxygen around the body.
handline simple hand-operated fishing line used without a rod and reel.
haremic pertaining to a social group containing a dominant male and a number of subordinate females.
hastate having the form of a triangular spearhead.
head depth vertical distance between the upper and lower profiles of the head, often at a specified location, eg posterior margin of the eye.
head length horizontal distance between the most anterior point on the snout or upper lip and the most distant point on the opercular membrane.
herbivorous feeding on plant material.
hermaphrodite (adj. hermaphroditic) having both male and female organs in the same body, although not necessarily developed functionally at the same time.
heterocercal referring to a caudal fin in which the upper lobe is noticeably larger than the lower lobe.
high-latitude latitude well away from the equator.
HL head length.
Holarctic the entire arctic region (in oceanography).
holdfast attaching base of seaweed.
holotype the single specimen designated or indicated as 'the type-specimen' of a nominal species-group taxon (species or subspecies) by the author at the time of the original publication (or the single specimen when no type was specified but only 1 specimen was present for the description).
humeral pertaining to the shoulder.
humeral spine cleithral spine.
hyaline transparent, clear.
hybridise produce offspring from different species.
hyoid non-functional remnant of an anterior gill arch just posterior to the mandibular arch that has given rise to the lower jaw; provides a base for the chin barbel in stomiid fishes.
hyomandibular major bone forming the rear part of the suspensorium.
hypobranchial rather short bone providing the internal skeleton for the basal end of the lower limb of anterior gill arches.
hypural the expanded and sometimes fused lower spine-like elements of the last few vertebrae that support the caudal fin.
IC ventral series of photophores, comprising IP+PV+VAV+AC.
iliac pelvic spines spine-like processes directed ventrolaterally from the lower end of the pelvic girdle.
illicium (adj. illicial) slender and sometimes jointed appendage (fishing rod) on the head of anglerfishes and their relatives.
imbricate(d) imbricating overlapping, as in roof shingles.
incised having a notched margin (particularly with regard to a membrane).
incisor (adj. incisiform) tooth with a flattened chisel-like tip, modified for cutting.
incubate to maintain eggs at optimal environmental conditions for growth and development.
Indo-Pacific of the Indian and Pacific oceans.
inferior mouth ventrally positioned mouth, below or underneath the snout.
inferior tail ridge in the Syngnathidae, the longitudinal ridge on the ventral margin of the tail rings, abbreviated ITAR.
inferior trunk ridge in the Syngnathidae, the longitudinal ridge on the ventral margin of the trunk rings, abbreviated ITR.
infracaudal on the underside of the caudal peduncle.
infraclass taxonomic grouping infrequently used between class and order.
infraorbital pertaining to the suborbital bones.
insertion (of a fin) base of the fin, where it joins the body, usually pertaining to the origin or forwardmost extent.
insular pertaining to an island.
integument outer covering of the body.
inter (prefix) between.
interbreed breeding between species or populations.
interdorsal distance distance between the dorsal fins.
interdorsal ridge fleshy ridge on dorsal midline of body between dorsal-fin bases, characteristic of certain sharks.
intermaxillary between the maxillae on the 2 sides.
internarial space area between the nostrils.
internasal distance distance between the nostrils.
internasal flap fleshy flap extending between the nostrils and partly covering the mouth of some rays and sharks.
internasal valve fleshy flap of skin between the nostrils of rays.
interopercle often narrow bone forming the edge of the gill cover posterior to the subopercle and the lower part of the opercle.
interorbit (adj. interorbital) area between the eyes, on top of the head.
interorbital width shortest distance on top of the head between the eyes measured from the bony orbital rims.
interpelvic space between the ventral-fin bases.
interspace intervening space.
intersphenotic distance between the anterolateral angles of the sphenotic bones that form the dorsolateral surfaces of the cranium immediately behind the orbits.
interspinous between the spines, as interspinous membrane - the fin membrane supported by spines anteriorly and posteriorly.
intertidal region between the edges of the high and low extremes of the tide.
intromittent oragan specialised structure of a male used to deposit sperm into the female.
invertebrate multi-cellular animals that have not evolved a notochord.
IP ventral series of photophores anterior to pectoral-fin base.
iridescent showing colours like those of the rainbow.
iris flat, usually circular coloured membrane behind the cornea of the eye with a circular opening in the centre.
isocercal pertaining to a perfectly symmetrical tail fin without upper and lower lobes.
isthmus fleshy area on the underside of the head that separates the two gill chambers.
ITAR inferior tail ridge.
ITR inferior trunk ridge.
IUCN The World Conservation Union (International Union for the Conservation of Nature and Natural Resources).
IV ventral series anterior to ventral-fin base.
IV ventral series of photophores anterior to ventral-fin base, comprising IP+PV.
joint structure in the body by which two bones are joined together.
jugular pertaining to the throat.
keel fleshy or bony ridge, usually on the sides, belly, or caudal peduncle.
knot speed equivalent to 1 nautical mile per hour (approximately 1.85km per hour).
krill eupahusid, shrimp-like crustacean that feeds on phytoplankton and often occurs in huge numbers.
labial pertaining to the lips.
lacrymal foremost circumorbital bone immediately in front of each eye (see 'preorbital').
lamella (pl. lamellae) thin plate, layer or film, especially of bone or tissue.
lamina (pl. laminae) lamella, often with a stratified structure.
lanceolate spear- or lance-shaped.
lappet lobe-like structure, often associated with the iris in the eye.
larva (pl. larvae adj. larval) immature stage of a fish, which differs greatly in appearance from the adult.
lateral line (scales) row or rows of pored scales or sensory pores in the skin along the side of the body; counted as the number of pore bearing scales from the upper end of the gill opening to the base of the caudal fin.
lateral midline lengthwise centre of the side.
lateral tail ridge in the Syngnathidae, the longitudinal ridge laterally on the tail rings, abbreviated 'LTAR'.
lateral trunk ridge in the Syngnathidae, the longitudinal ridge laterally on the trunk rings, abbreviated 'LTR'.
lateral(ly) (comb. latero-) adj. referring to the side, away from the centre.
lateralis laterosensory.
laterosensory sensory system comprising regularly arranged surface pores opening from a subcutaneous system of canals with receptors capable of detecting low frequency vibrations (movements).
lath-like similar to thin strips of sawn or split timber for use as internal support for hard plaster.
latitude angular distance from the equator North or South measured in degrees, minutes and seconds.
lectotype one of several type-specimens designated after the publication of a species-group name, as the type-specimen of the taxon bearing that name; designated only where there was no original holotype.
lens transparent substance with curved sides for the concentration or dispersal of light.
leptocephalus (pl. leptocephali) transparent leaf-like pelagic larval form of eels and their close relatives.
light organ light-producing organ structure that produces light by a chemical reaction (bioluminescence), either directly by special body cells or through luminescent bacteria cultured in body tissues.
limb appendage, such as a leg, arm or wing, or section of a continuous structure, like a gill arch.
lingual of the tongue.
litter offspring produced at the same time.
live-bearing retention of eggs within the body cavity of the mother, releasing free-swimming young at birth.
LL Llat lateral line.
lobe (adj. lobate) roundish and flattish projection or pendulous part.
long-based having a long base.
longitude angular distance on the Earth's surface, measured East or West from the prime meridian at Greenwich, England, to the meridian passing through a position, expressed in degrees, minutes, and seconds.
longitudinal along the length.
longitudinal series number of scales in a longitudinal row along the length of the body.
longline fishing gear comprising a line of considerable length off which hang many shorter lines with baited hooks, the main line usually set horizontally in the water column.
LTAR lateral tail ridge.
LTR lateral trunk ridge .
luminescent luminescence producing light.
luminous infracaudal organ light organ on underside of caudal peduncle.
luminous organ light organ; specialised part of the body that produces light, usually without a lens.
luminous supracaudal organ light organ on top of caudal peduncle.
lunate shaped like a crescent moon, pertaining to the tail fin.
lure structure used to entice potential food items within striking distance of its predatory owner.
m metre(s).
mail-cheeked having horizontal spiny ridge or other protective covering on the side of the head beneath the eye.
malar pertaining to the forward portion of the upper surface of the pectoral fins (fused with head) in rays.
mandible (adj. mandibular) lower jaw.
mandibular pores pores of the cephalic lateralis canal system laterally on the lower jaw.
maori-like having markings like the tattoos of the Maori people of New Zealand.
marbled having mottled or streaked colouration like marble limestone.
mature fully developed and capable of reproduction.
maxilla (pl. maxillae maxillaries adj. maxillary) hindmost of two pairs of bones forming the lateral margin of the upper jaw.
medial(ly) towards the middle of the body (towards the vertical plane).
median pertaining to the middle (vertical plane).
medusae sea jellies (jellyfish).
melanophore black pigment cell or chromatophore.
membrane thin layer of connective tissue.
meristic countable.
mesial(ly) (comb. meso-) adj. towards the middle or medial plane.
mesopelagic free swimming in the open ocean at depths from 200m to 1000m.
mesopterygoid bone in the suspensorium that forms part of the roof of the mouth on either side behind the palatines.
metabolism chemical processes within living tissue or organisms necessary for the maintenance of life, involving the breaking down of substances to yield energy for vital processes and the synthesis of others, necessary for life.
metalarval stage stage of larval development at the point of changing to the adult configuration.
metamorphosis the marked changes in body form during growth, most frequently from the larval to the adult stages.
microhabitat natural home and immediate surroundings (fine scale perspective).
micronekton microscopic component of free swimming animals in a body of water.
mid (adverbial prefix) halfway or at the centre, as in midcaudal - at the centre of the caudal.
midline longitudinal centre.
midpoint centre.
midside central part of the side laterally.
midventral centre of the underside.
mid-water occurring in the open ocean well above the bottom and well away from the ocean surface, usually at greatly reduced light levels or in darkness.
minute tiny.
mm millimetre(s)
mode way in which things are done; prevailing fashion.
molar (adj. molariform) blunt, rounded tooth, adapted for grinding.
mollusc member of a major invertebrate group typically having a soft unsegmented body, a mantle and usually a protective calcareous shell or shells; includes snails, slugs, bivalves, octopus, squid, etc.
monophyletic sharing a common ancestor.
monospecific having only a single species.
monospondylous having a single vertebra in each body segment, as in the trunk of certain fishes; in cartilaginous fishes, vertebral centra larger than diplospondylous vertebral centra.
monotypic having only a single species.
morphology (adj. morphological) the anatomical form and structure of organisms.
morphometrics morphometry measurements of body structures.
mosaic made up of many small non-uniformly coloured or textured parts.
mouth width transverse distance between corners of mouth.
mouthbrooding retaining eggs within the mouth, usually by the male, while they develop, thus improving their chance of survival.
MP mandibular pores.
MPAs marine protected areas
mucous mucus slimy substance produced by cells in the skin of fishes.
multicuspid having many points or projections.
multifid divided into many parts or lobes.
multilobed multilobate having many lobes.
multiserial having more than one series or row.
myomere myotome segment of body muscle (muscle block).
naked skin that is smooth and without scales.
nape upper surface in front of the dorsal fin, just behind the head.
nares (adj. narial) nostrils.
nasal relating to the nose or nostril.
nasal curtain internasal flap; fleshy flap extending between the nostrils and partly covering the mouth of some rays and sharks.
nasal organ sensory organ for detecting smell.
nasal rosette nasal organ, having prominent fan-like laminae equipped with numerous olfactory sensory organs to enhance smell capability.
nasal tentacle thick fleshy filament near the nostril.
nasal valve nasal opening.
nasoral groove furrow connecting the mouth to the nasal organ, usually concealed beneath internasal flap.
neotype a single specimen designated as the type-specimen of a nominal species-group taxon of which the holotype (or lectotype), and all other type specimens are lost or destroyed or suppressed by the International Commission on Zoological Nomenclature.
neurocranium the part of the skull that surrounds the brain.
neuromast free nerve endings having a sensory function.
nictitating membrane clear membrane at the front of the eye that can be pulled over the surface of the eye for protection.
nocturnal active at night.
non-serial photophore isolated photophore not part of a photophore series.
nostril pore-like opening of the nasal organ; many species having two pairs, an anterior nostril and a posterior nostril.
notch indentation.
notochord rudimentary or embryonic spinal cord or spinal column appearing as a clear, stiffened rod.
notochord A flexible, rod-shaped structure found in the embryos of all chordates. In most vertebrates it becomes ossified to form the vertebral column, although it persists throughout life as the main body support in hagfishes and some invertebrates.
nuchal pertaining to the nape.
nuptial tubercles small abnormal horny outgrowths that become evident just before spawning and disappear shortly afterwards under the influence of hormonal secretions.
nursery space where offspring are raised.
OA lateral series of photophores.
oblique slanting or declining from the vertical or horizontal; not at right angle.
oblique scale rows diagonal scale rows; regular arrangement of scales in slanted rows along the side of a fish's body usually counted above the lateral line, if present, from the edge of the operculum to the posterior edge of the hypurals.
obsolescence no longer of use.
obtuse not pointed; with a blunt end, forming a broad angle.
occipital (n. occiput) pertaining to the back part of the top of the head (or the occipital bones of the skull).
oceanic of the open ocean.
Oceanodromy migration between marine habitats.
ocellus (pl. ocellae adj. occellated) an eye-like spot with a marginal ring (often a dark spot with a pale marginal ring).
ocular pertaining to the eye.
olfactory pertaining to the nasal organs or the sense of smell.
olfactory organ organ for the sense of smell.
oophagous feeding on eggs.
ooze mud; very fine soft sediment.
Op 'cheek' photophores on opercle.
OP opercular photophores.
opercle large, posterior bone of the gill cover.
opercular pertaining to the operculum or gill cover.
opercular membrane membrane around the free edge of the gill cover providing a seal across the gill opening when water is drawn into the mouth for respiration.
operculum (pl. opercula) bony flap (supported by several individual bones), which covers the gills.
oral disc circular mouth of lampreys.
ORB 1 photophore anterior to eye.
orbit (adj. orbital) bony eye socket.
orbital tentacle filamentous fleshy outgrowth, usually above the eye.
orbital thorns enlarged spine-like denticles partially encircling medial side of orbit in some skates.
order (adj. ordinal) commonly used major grouping in classification falling between class and family.
origin the most anterior point of the base of a fin, a spine, or a ray.
osmosis (adj. osmotic) tendency of a fluid to move through a selective barrier into a more concentrated solution.
ossicle plate of bone-like material.
ossify (n. ossification) to turn into bone.
ostracitoxin tetrodotoxin; virulent poison, capable of causing death, present in certain body tissues of pufferfishes and some of their relatives.
ostracod small crustacean with a pair of clam shell-like valves for protection.
ostracoderm extinct group of fishes best known for its outer bony covering or exoskeleton.
otolith oval-shaped calcareous structures in the ear capsules of bony fishes (earbones).
OV lateral series of photophores, subdivided into anterior OVA and posterior OVB.
ovate ovoid oval-shaped.
oviparous eggs that hatch outside the body of the female parent.
oviphagous method of embryonic nutrition where the embryo feeds on unfertilised eggs or other embryos with the uterus.
ovoviviparous producing eggs with a definite shell that hatch within the body of the female parent.
ovulate to release eggs from the ovary.
P number of elements in each pectoral fin, usually comprising just soft rays (Arabic numerals).
palate roof of the mouth.
palatine one of a pair of elongated bones on the palate just lateral to and behind the vomer; the anteriormost bone of the suspensorium.
palatoquadrate that portion of the suspensorium extending from the jaw hinge to the front of the neurocranium.
papilla (pl. papillae adj. papillate papillose) small fleshy projection.
parasitic living for some period of time, to its own benefit, in or on another organism (the host) to the host's detriment.
particulate in the form of separate particles.
PC pyloric caecae
pectoral pertaining to the breast region.
pectoral disc flattened disc-like body of skates and rays formed from the union of the pectoral fins with the head and body.
pectoral fin usually the most anterior of the paired fins, situated in the breast region or midlaterally on the side just behind the head (corresponding to forelimbs in terrestrial vertebrates).
pectoral girdle skeletal support for the pectoral fin.
pedicel stalk-like structure.
peduncle narrow stalk-like structure (most frequently referring to the caudal peduncle).
pelagic free swimming in the open ocean and seas.
pelvic bone see 'pelvis'.
pelvic fin ventral fin; each of the paired fins situated ventrally and usually below or behind the pectoral fins (corresponding to hind limbs in terrestrial vertebrates).
pelvic girdle skeletal support for the ventral fin.
pelvis basal bony support for the ventral or pelvic fins.
periphery (adj. peripheral) outer margin.
periproct scaleless area surrounding anus.
peritoneum thin membrane that lines the abdominal cavity.
pharynx (adj. pharyngeal) gullet or back part of the throat into which the gills slits open.
phosphorescent emission of light without combustion or perceptible heat.
photophore small, circular light-producing organ on the surface of the body.
phylogeny (adj. phylogenetic) pertaining to interrelationships based on ancestry.
piebald of two colours irregularly arranged, especially black and white.
pinnacles natural peak ending in a pyramid- or crown-like form.
pit indentation or hollow in a surface.
placenta flattened circular spongy vascular tissue in the uterus that helps to nourish a developing foetus in live-bearing individuals.
Placental viviparity The embryos initially rely on stored yolk and are then nourished directly by the mother through a yolk placenta.
planktivorous feeding on plankton.
plankton (adj. planktonic) small animals or plants that drift passively with the ocean currents.
platelets small discs, often with slightly concave centres.
pleural rib slender paired bones based on the vertebral column that provide the structural support for the membrane surrounding the body cavity in which the swim bladder and major digestive and reproductive organs are contained.
plicate pertaining to skin arranged in pleat-like folds.
PLO photophore above pectoral-fin base.
PO ventral series of photophores in front of ventral fin.
Po postorbital photophore posteroventral to eye.
Pol lateral photophore(s) between adipose fin and posterior part of anal fin.
polychaete bristle worm; major group of annelid worms, particularly diverse in the marine world.
polygonal referring to an enclosed shape with many (usually more than four) sides and angles.
polyp individual member of a coelenterate colony, usually consisting of a tubular body with an oral opening surrounded by a circle of tentacles at the distal end.
POP preopercular pores.
pore small opening or pit, as in the lateral-line pores.
Posidonia a genus of marine flowering 'seagrass ' plants with moderately broad flat leaves.
post (adverbial prefix) coming after or behind, such as postorbital - behind the orbit or eye.
posterior(ly) (comb. postero-) adj. relating to the hind region.
posterolateral hind region along the side.
post-larvae (adj. postlarval) newly settled larvae that have not yet acquired the juvenile configuration.
postocular behind the eye.
postorbital behind the orbit.
posttemporal portion of the head or skull on either side behind the orbits.
posttemporal bone superficial bone suspending the upper end of the pectoral girdle from the cranium on either side behind the orbits, and enclosing a section of the laterosensory canal.
pouch bag-like cavity.
Prc ventral series of photophores just in front of caudal-fin base.
pre (adverbial prefix) coming before or in front of, such as preorbital - in front of the orbit or eye.
preanal-fin chambers series of lymph compartments within the finfold on the ventral side of the body in advance of the anus.
prebranchial length distance from the front of the rostrum to front of first gill aperture.
prebranchial slime pores slime pores from the anteriormost to the last pore before the first gill aperture.
precaudal anterior to the tail region.
precaudal length length from snout tip to upper caudal-fin origin.
precaudal pit notch on the caudal peduncle just before the caudal fin.
precaudal vertebra vertebra associated with the abdominal cavity, lacking a haemal spine.
precloacal length length from snout tip to anterior extent of the cloacal opening.
predorsal anterior to the origin of the first dorsal fin.
prehensile adapted for holding, as in the tails of monkeys or the snout of elephants.
prejuvenile early life stage just prior to acquisition of juvenile characteristics.
pre-mature not yet capable of reproduction.
premaxilla (pl. premaxillae adj. premaxillary) one of the paired bones forming the front of the upper jaw, usually bearing teeth.
preocular in front of the eye.
preopercle (adj. preopercular) the bone situated behind and below the eye and in front of the opercle.
preoral pertaining to the area in front of the mouth.
preoral groove (preoral cleft) groove before the mouth.
preoral length shortest distance from the snout tip to the mouth.
preorbital in front of the orbit.
preorbital bone lacrymal; anteriormost (first) suborbital bone.
preorbital length shortest distance from the snout tip to the orbit.
prepelvic claspers small, retractable appendages on each side just forward of the ventral fins of mature male chimaeroid fishes; concealed with a slit when retracted; prepelvic tentacula.
preural pertaining to the next to the last vertebral element of the vertebral column.
primary photophores those photophores occurring in the majority of the species, including serial photophores and recurring isolated photophores.
principal ray one of the major segmented and often branched rays supporting the caudal fin and articulating with the hypural bones basally (in most fishes the number of principal rays equals the number of branched rays + 2 unbranched rays).
proboscis elongated, flexible extension of the snout.
process natural appendage, outgrowth or protuberance.
procurrent ray each of the small unbranched and often unsegmented rays in the tail of many fishes situated on the dorsal and ventral margins of the caudal peduncle in front of the principal rays.
protolarval stage earliest larval stage.
protractile capable of being extended forwards; protrusible.
protruding (adj. protrusible) thrusting forth, projecting, often pertaining to the jaws of fishes.
protuberance bulge, prominence.
province major area of natural distribution in a biogeographical sense.
proximal part of a structure nearest the base or point of attachment.
pseudobranch remnant of the hyoid gill arch attached to the inner surface of the gill cover; covered by skin in some fishes.
pterotic each of a pair of bones on<em> </em>either side forming a portion of the neurocranium (brain case) behind and slightly above the eye.
pterygiophore three-part internal skeletal support at the base of each of the dorsal- and anal-fin spines and rays.
pterygoid ectopterygoid; a bone in the suspensorium on the posterior part of the palate.
pungent stiff and sharply pointed, as in some spines.
pupil circular opening in the centre of the iris of the eye.
purgative having the effect of a strong laxative; causing evacuation of the stomach and bowels.
PV ventral series of photophores between bases of pectoral and ventral fins.
PVO lateral photophores ventral, opposite, and/or dorsal to pectoral-fin base.
pyloric caecum (pl. pyloric caecae) tubular sac attached to the stomach.
quadrangular with four angles and edges.
quadrate bone in the suspensorium with which the lower jaw is hinged.
radials series of column shaped bones in the pectoral girdle providing a base distally for the pectoral-fin spines and rays and articulating with the coracoid and scapula proximally.
raker see 'gill raker'.
rapacious grasping; predatory.
ray flexible, usually segmented structure that supports a fin.
receptors organs of sensory reception.
recurved curved backwards or inwards.
reflector surface causing light waves to rebound.
regressed having gone backwards.
resorbed absorbed again.
retia rete mirable; highly vascularised organ within the gas bladder responsible for gas secretion.
reticular (reticulate n. reticulation) divided into a network; arranged in small squares or with intersecting lines.
rhomboid (adj rhomboidal) having a 4-sided (quadrilateral) shape with only the opposite sides and angles equal.
riverine of or on a river, or its banks.
rostrum (adj. rostral) projecting snout or beak.
rudimentary (n. rudiment) very small and poorly formed; undeveloped; imperfectly developed.
rugose with a rough surface.
sac bag-like membrane-enclosed cavity.
saddle marking on the back resembling a horse's saddle.
salp barrel-shaped free-floating tunicate that moves by pumping water through its gelatinous body by means of contraction, and strains the water, feeding on phytoplankton.
SAO lateral series of photophores above anus.
sashimi Japanese food consisting of raw fish.
scale rows between dorsal-fin base and lateral line scales above lateral line (see above).
scale rows between lateral line and ventralfin base scales below lateral line (see above).
scaled having scales.
scales above lateral line regular arrangement of scales in slanted rows between the dorsal margin of a fish's body to, but not including the lateral line, counted downward and backward from the base of the first dorsal-fin spine (or ray if spines are absent) unless otherwise stipulated.
scales below lateral line regular arrangement of scales in slanted rows between the ventral margin of a fish's body to but not including the lateral line, counted upward and forward from the base of the first anal-fin spine (or ray if spines are absent) unless otherwise stipulated.
scalloped with a series of rounded projections along the margin or edge, like the outer margin of a scallop shell.
scavenger feeding on carrion.
schooling forming a shoal or aggregation.
scribbling resembling hurried or careless writing.
scull propel by moving oar-like structure from side to side in a twisting fashion.
scute bony plate or ridged scale.
scutellum (pl. scutella) shield-lie scale.
SDR subdorsal rings.
sea jelly jellyfish; marine invertebrates of the phylum Cnideria, whose adult body is composed of a bell-shaped, jellylike substance enclosing its internal structure, with tentacles suspended beneath.
sea urchins members of the phylum Echinodermata, with globular, usually rigid body having a five-part symmetry, covered by spines and moving by means of hundreds of tiny, transparent, adhesive 'tube feet'.
seagrass marine flowering plants with grass-like form.
seamount underwater mountain.
seaweed any of a large number of marine benthic algae.
secondary photophores photophores occurring in a relatively few number of species, other than regular serial photophores and recurring isolated photophores.
secrete (n. secretion) excrete substance, separated from blood, to the exterior.
sedentary characterised by little movement or swimming.
segmented ray fin ray divided into segments along its length.
seine fishing net with floats at the top and weights at the bottom used to encircle fish, and usually hauled ashore.
semi-detached partly connected and partly free.
sensory canal/pore canal or pore associated with the electrosensory or laterosensory systems.
serial(ly) of, in or part of a series.
serrae (adj. serrated) notches, like those of a saw.
sessile fixed in one position, immobile.
sexual dimorphism (adj. sexually dimorphic) difference in physical appearance between males and females.
shelf see 'continental shelf'.
shovelnose having a spatulate snout.
siltation the act of having sediment deposited by water.
simple not divided into branches.
skin fold area where skin is bent over upon itself, forming a flesh ridge.
SL standard length.
slime pores series of pores along the flank of hagfishes that produce large amounts of slime used in defense or in suffocating other fishes.
slope see 'continental slope'.
snout upper part of the head in front of the eyes.
So photophore just below eye.
SO paired photophores near symphysis of lower jaw.
soft dorsal dorsal fin supported entirely or almost entirely of soft rays.
soft ray fin ray that is bilaterally paired and often segmented and branched.
SOP supraoccipital pores.
Sor suborbital photophore anteroventral to eye.
spatulate with a broad, flat and rounded shape.
specific pertaining to species.
speciose composed of many species.
sperm male sex cell.
sphenotic each of a pair of bones on either side forming a portion of the neurocranium (brain case) immediately behind and slightly above the eye, just below the frontal bone.
spheroid sphere-like but not a perfectly spherical body.
spinal column vertebral spine.
spine sharp pointed projection, often supporting a fin; in reference to fin spines, each element being undivided and unsegmented.
spiniform spinoid having the shape of a spine.
spinoid scale cycloid scale with a serrated margin; superficially similar to ctenoid scales but with spines as outgrowths of the scale, as opposed to true ctenii.
spinous composed of spines or spine-like.
spinule (adj. spinular spinulate spinulous) a small spine.
spiracle opening behind the eye in sharks and rays with an open passage to the pharynx, used in respiration.
spiral valve spiral or helical fold in the midgut of primitive fishes that increases the surface area for processing food without lengthening the intestine.
splint bone modified first ventral-fin ray that is unsegmented and not bilaterally paired.
spur hard, pointed projection.
squalene oil produced in the liver of some sharks.
stalked on a peduncle or stem-like structure.
standard length length of a fish measured from the tip of the snout to the end of the posterior edge of the hypurals, abbreviated 'SL'.
STAR superior tail ridge.
stellate star shaped.
STR superior trunk ridge.
striae striations.
striated (n. striation) having a series of linear marks on the surface.
stripe lengthwise strip of colour.
sub (prefix) below, as in 'subrostral', or almost but not quite, as in 'subterminal mouth'.
subadult maturing individual that is almost capable of reproduction.
subantarctic biogeographic region of the Southern Ocean in the vicinity of 50 degs latitude.
subarctic region well away from the equator but not close enough to the North Pole to be regarded as arctic.
subcircular nearly circular.
subclass division of classification immediately below class, between it and the level order.
subcontinuous slightly interrupted.
subcutaneous below the skin.
subcylindrical not quite cylindrical.
subdermal below the skin.
subdorsal rings in the Syngnathidae, the number of trunk rings beneath the dorsalfin base + the number of tail rings beneath the dorsalfin base, abbreviated 'SDR'.
subequal almost equal.
subfamily division of classification immediately below family, between it and the level genus.
subgenus (pl. subgenera) grouping of closely related species with a common ancestry below the generic level; only recognised if there are at least two such groupings in the genus.
subinferior extremely inferior, as in subinferior mouth - a mouth on the underside of the head well away from the tip of the snout.
subopercle bone forming a portion of the operculum immediately below the opercle.
suborbital referring to below the orbit or eye.
suborbital bones infraorbital bones, ventral series of circumorbital bones not fused with the neurocranium.
suborbital stay bony ridge beneath the eye extending from the suborbital bone across the cheek to the preopercle, or almost to the preopercle.
suborder division of classification between the levels of order and family.
subphylum (pl. subphyla) division of classification below the level of phylum composed of one or more classes containing species that have a common ancestry.
subrhombic almost diamond-shaped; nearly an oblique equilateral parallelogram.
subrostral referring to below the snout.
subspecies (adj. subspecific) population confined to a particular geographic area within the overall range of a species that differs in a consistent way from populations elsewhere in the range.
substrate substratum underlying layer or substance; foundation.
subtemperate on the polar side of a temperate region.
subterminal mouth mouth opening on the underside of the head almost at the anterior end.
subtidal(ly) below the low tide mark.
subtriangular nearly triangular.
subtropical at the periphery of the tropical region, almost temperate.
subvertical approaching the vertical.
sucking disc (suction disc) disc-like structure on the head of Echeneidae comprised of a series of thin movable plates called laminae; or ventral disc formed, in part, from united ventral fins of Gobiesocidae used to attach fish to rocks or vegetation.
suctorial capable of sucking; having a sucker for adhering to an object.
suffused suffusion an overspreading of colour.
Suo light organ dorsoposterior to eye.
super (prefix) situated directly over, or more than.
superclass division of classification immediately above class, between it and the level phylum.
superior tail rings in the Syngnathidae, the longitudinal ridge on the dorsal margin of the tail rings, abbreviated 'STAR'.
superior trunk rings in the Syngnathidae, the longitudinal ridge on the dorsal margin of the trunk rings, abbreviated 'STR'.
superorder division of classification immediately above order, between it and the level class.
superspecies division of classification immediately above species, made up of two or more very similar species.
supra (prefix) above, as in supraorbital - pertaining to the region above the orbit (eye).
suprabranchial pores posteriormost pores above the gill opening in the temporal pore series of cephalic sensory pores.
supracarinalis anterior lengthwise muscle connecting the rear of the skull dorsolaterally with the first pterygiophore of the dorsal fin anterordorsally.
supracaudal on top of caudal peduncle.
supracleithrum paired dermal bone of the secondary pectoral girdle above the cleithrum and below the posttemporal.
supramaxilla supramaxillary (also as adj.) one or two dermal bones on the upper side of the posterior end of the maxilla in more primitive fishes.
supraneural one of a median series of detached, usually ossified rods lying in the flesh between the head and the dorsal fin, presumably representing detached neural spines.
supraoccipital median bone at the upper rear end of the neurocranium, often bearing a crest, and forming the top edge of the foramen magnum.
supraocular ridge one of a pair of lengthwise bony ridges between the eyes.
supraorbital above the eye.
supraorbital canal cephalic sensory canal extending from above the eye to the nostrils.
suprascapula bone or cartilage that joins the shoulder girdle to the skull.
supratemporal above the posterolateral (temporal) region of the skull.
suspensorium bone series on either side suspending the lower jaw from the neurocranium or braincase.
suture ragged line of union between two bones cemented with connective tissue, allowing no movement.
swimbladder gas-filled sac lying in the body cavity beneath the backbone that provides the fish with some buoyancy.
symbiosis (adj. symbiotic) the living together of 2 species to their mutual benefit.
sympatric having distributions that overlap geographically.
symphysis (adj. symphysial) the junction or site of fusion between two bones or parts of the anatomy, especially in the median plane of the body, often the midline of the lower jaw.
syntypes specimens on which a species name is based where one has not been singled out as the holotype.
tab small flap.
tail length distance from the origin of the cloaca to the posterior margin of the caudal fin.
tail rings in the Syngnathidae, body rings on the tail posterior to the anal ring, abbreviated 'TAR'.
tail slime pores the series of slime pores that starts about over the anterior margin of the cloaca to the last pore on tail.
TAR tail ring.
Tas Tasmania.
taxon (pl. taxa) a particular natural unit within a classification; a taxonomic unit.
taxonomy (adj. taxonomic) the science of classifying.
telescopic eye an elongated, cylindrical eye that protrudes forward or upward within an envelope of skin.
tenaculum spiny, club-shaped organ on the head of male chimaeroids apparently used during mating.
tendril curling filamentous projection.
tentacle (adj. tentacular) short fleshy appendage; cirrus.
terminal towards the end; at the end.
terrestrial living on land.
tetrapod vertebrate animal having two pairs of limbs and feet.
tetrodotoxin virulent poison occurring within certain tissues of some, if not all, tetraodontiform fishes.
thoracic pertaining to the chest or region of the body near the head.
thorn large spine or denticle.
tidal associated with the periodic rise and fall of ocean water produced by gravitational effects of the moon and sun on the earth.
TL total length.
total length body length measured from the tip of the snout to the tip of the tail, abbreviated 'TL'.
toxic poisonous.
TR trunk ring.
transverse from side to side; extending across.
transverse scale rows regular arrangement of scales in slanted rows between the dorsal and ventral margins of a fish's body; counted as the number of scales above the lateral line + 1 lateral-line scale + the number of scales below the lateral line.
tribe a division of classification between the levels of family and genus.
tricuspid(ate) tridentate having 3 cusps or points (usually in reference to teeth.
trifid divided into three.
trilobed having three lobes.
triradiate having three parts or limbs that are directed outward from a central point.
truncate with a straight margin; abruptly cut off.
trunk that part of a fish between the posterior border of the opercular membrane and the anus.
trunk length distance from the front of the last gill aperture to the origin of the cloaca.
trunk rings in the Syngnathidae, body rings on the trunk anterior to and including the anal ring, abbreviated 'TR'.
trunk slime pores series of slime pores posterior to the gill apertures, terminating just before the cloaca; distinctly separated from the tail series.
tubercle (adj. tubercular tuberculate) a small, usually hard protuberance on the body.
tubule slender tube, often involved in conveying fluids.
tunicate member of the primitive chordate subphylum Urochordata, some having an attached barrel-shaped adult stage and others being clear, gelatinous and planktonic as adults.
turbid muddy; not clear.
unicuspid unicuspidate having a single point or cusp.
unilateral 1-sided; done by or affecting only 1 person.
uniserial in a single row.
unossified not turned to bone.
unpaired fin singular fin on the dorsal or ventral midline of the body; dorsal, anal or caudal fin.
upper jaw length distance between the anterior and posterior extents of the upper jaw, following the line of the jaw.
upwelling movement of water from great depths to the surface.
urea waste product of metabolism excreted via the kidneys but also found in the blood of sharks and rays to maintain osmotic balance.
urogenital pertaining to the urinary and reproductive organs.
urogenital papilla genital papilla; a small fleshy projection behind the anus, through which the genital and sometimes urological system communicates with the exterior.
uterus the organ where fertilised eggs develop.
V number of elements in each ventral fin, often comprising a spine (Roman numeral) and soft rays (Arabic numerals).
VAL lateral series of photophores from just behind ventral-fin base to just behind anal-fin origin.
variegated marked with irregular patches of different colour.
VAV ventral series of photophores between ventral-fin base and anal-fin origin.
venom poisonous fluid injected into prey by biting or stinging.
venomous capable of producing and injecting a toxic or poisonous substance.
vent anus, external opening of the alimentary canal.
ventral fin pelvic fins; paired fins on the ventral surface between the head and the vent, corresponding to the hind limbs of terrestrial vertebrates.
ventral finfold ridge of thin, fleshy tissue extending along the ventral midline of the body.
ventral(ly) (comb. ventro-) adj. pertaining to the undersurface or underside.
ventrolateral(ly) pertaining to the region between the ventral and lateral surfaces; the lower side of the body.
vermiculate (n. vermiculation) marked with close wavy, worm-like lines.
Vert number of vertebrae in the vertebral column, often comprising precaudal vertebrae + caudal vertebrae.
vertebra (pl. vertebrae adj. vertebral) one of a series of bony or cartilaginous elements surrounding the notochord, or replacing it, and often protecting the spinal cord and caudal vein.
vertical fin dorsal, anal and caudal fins; unpaired fins on the upper and lower midlines of the body.
vestigial reduced to very small or undeveloped vestige.
vexillum extremely elongated first ray in the dorsal fin of some fish larvae.
villiform tooth small, slender tooth, set in bands.
viviparous producing live young, the developing young nourished by the mother's body until they are released to the outside.
VLO supraventral photophore above the ventral fin.
Vn light organ anteroventral to eye.
VO ventral series of photophores between ventral and anal fins.
vomer (adj. vomerine) median bone at the front of the neurocranium, detectible at the front of the roof of the mouth, sometimes bearing teeth.
warm temperate near tropical, warmer extent of a temperate region.
yolk granules of semi-crystalline phospholipoprotein used as a nutrient store during embryonic development.
yolk-sac sac containing yolk used for nourishment in larval fish.
zooplankton small animals or larva that drift in the water.
Zostera eelgrass; a small genus of widely distributed seagrass with long, bright green, ribbon-like leaves, about 1cm wide growing from extensive, white branching runners.