Family PLATYTROCTIDAE


Common name: Tubeshoulders

Silhouette

Summary:

A moderately large family of elongate deepwater fishes with a naked head and soft, watery flesh covered with scales. Tubeshoulders have a unique shoulder organ - a sac containing luminous fluid located beneath the cleithrum bone. The fluid is released via a black tube supported by a modified lateral-line scale, and is thought to distract predators, allowing tubeshoulders to escape.


Cite this page as:
Dianne J. Bray, Tubeshoulders, PLATYTROCTIDAE in Fishes of Australia, accessed 12 Dec 2018, http://fishesofaustralia.net.au/Home/family/74

More Info


Family Taxonomy

Moderately large family of rare deepwater fishes with 37 species in 13 genera; 4 genera and at least 6 species in Australian waters.

Family Distribution

Platytroctids are found worldwide over continental slopes, submarine rises and seamounts. They are bentho-, bathy- or mesopelagic in slope and abyssal depths, most between depths of 1000-3000 m. Some juveniles and smaller species often live in the open ocean, usually in depths between 800-2000 m.

Family Description

Body soft, elongate, usually laterally compressed, head naked in most, eye moderate to large, aphakic aperture well-developed; jaw teeth small, in single series, gill openings wide; shoulder area between lateral line and pectoral fin-base with a modified scale supporting a conspicuous, short, black tube producing luminous fluid; single dorsal fin well posterior over similar anal fin, pectoral fins low on body, pelvic fins abdominal, caudal fin forked, no adipose fin; body scales cycloid, lateral line system subcutaneus, visible as a series of tiny pores; some species with serial photophores on head and ventral profile.

Family Size

One species reaches a length of 35 cm; most reach lengths between 10 and 25 cm.

Family Feeding

Little known.

Family Reproduction

Eggs large, larval development direct. Larvae, long, slender, rare, distinguished from similar alepocephalid larvae in having a black luminous sac and shoulder tube opening clearly visible in very small larvae. Photophores if present appear in yolk-sac stage (13-15 mm SL); postflexion stage persists until pectoral fins are almost fully formed (up to 30 mm SL).

Family Commercial

Although tubeshoulders are occasionally taken in deep-sea trawls, they are of no commercial importance. One species, Persparsia kopua, is moderately abundant.

Family Conservation

IUCN Red List: Not evaluated

Family Remarks

Tubeshoulders are externally very similar in appearance to many of the common and abundant slickheads (family Alepocephalidae). They differ from slickheads in having a tube supported by a modified lateral-line scale at the shoulder, leading to a sac containing luminous fluid. This blue-green luminous fluid is produced from the black shoulder sac apparatus under the shoulder girdle. Unlike slickheads, tube-shoulders do not form groups or schools.

Author

Dianne J. Bray

References


Matsui, T. & R.H. Rosenblatt. 1987. Review of the deep-sea fish family Platytroctidae (Pisces: Salmoniformes). Bull. Scripps Inst. Oceanogr. Univ. Calif. 26: i-iv + 1-159.

Paxton, J. R. , J. E. Gates, D. J. Bray & D.F. Hoese.  2006. Family Platytroctidae, In Hoese, D.F., D.J. Bray, G.R. Allen, J.R. Paxton, Beesley, P.L. & A. Wells. Zoological Catalogue of Australia Volume 35, Parts 1 – 3. Fishes. CSIRO Publishing / Australian Biological Resources Study (ABRS). 2248 pp.

Sazonov, Yu. I. 1999. Family Platytroctidae. In Carpenter, K.E. & V.H. Niem. Species identification guide for fisheries purposes. The living marine resources of the western central Pacific. Batoid fishes, chimeras and bony fishes part 1 (Elopidae to Linophrynidae). FAO, Rome.

Sazonov, Yu. I., A.A. Balanov & V.V. Fedorov. 1993.Alepocephaloid fishes (Alepocephaloidei) from the western North Pacific Ocean. Trudy Inst. Okeanol. Akad. Nauk SSSR 128: 40-68. [In Russian, brief English summ.]

Williams, A. & Yu. I. Sazonov. 2008. Family Platytroctidae, In Gomon, M.F., D.J. Bray & R.H. Kuiter (Eds.) Fishes of Australia's Southern Coast. New Holland Publishers & Museum Victoria, Melbourne, Australia. P. 1-928.