Sad Seahorse, Hippocampus tristis Castelnau 1872

Endemic to subtropical waters of eastern Australia, from off southern Queensland to off Iluka, northern New South Wales, and off Adelaide, South Australia; also Lord Howe Island in the Tasman Sea. Trawled in depths of 18-62 m.

Dorsal fin 18-19; Anal fin 4; Pectoral fin 18-19; trunk rings 11; tail rings 35-37; subdorsal rings 2 + 1-2.
Juveniles spiny, large adults smooth. Nasal profile straight with a small spine; neck ridge short, distinctly raised above gill opening; double blunt spines ventrally on shoulder ring below pectoral fin.
Head and body spines small, blunt, proportionally smallest in largest specimens; most trunk ridges with low tubercles, males with tubercles mainly on inferior trunk ridges and on tail along pouch region; upper shoulder-ring spine small, situated just below gill opening; lower shoulder ring spine thick, knob-like, single or double with less developed secondary spine anteriorly; neck ridge short and distinctly raised above gill opening.
Coronet small but well developed, with 5 short spines on apex in young, spines becoming less prominent with age and almost smooth in large adults.
Lateral line pores small without papillae, more or less distinct, becoming intermittent on tail, ranging to 17^th ring.

In life, drab grey to pale brown, head and trunk dusky, sometimes with numerous tiny white spots in longitudinal lines; juveniles occasionally pale yellow; large juveniles occasionally with prominent saddle-like blotches, contrasting with general colour, at 1st, 4th and 8th trunk rings, and along tail. In preservative - cream to pale brown, with some dark spotting near eyes.

Like most other seahorses, this species presumably feeds by sucking small prey items such as crustaceans and zooplankton into its mouth.

Sexes separate; males give birth to tiny independent young. The female uses an ovipositor to transfer her eggs into an elaborate enclosed pouch under the abdomen of the male. The male not only fertilizes the eggs inside the pouch and provides physical protection for the developing embryos, he also osmoregulates and aerates the embryos and may provide some nourishment until the offfspring are born.

None. Although taken in commercial trawls, there is no known trade in this species for the aquarium or Asian Traditional Medicine industries.

International: Listed under Appendix II of the Convention on the International Trade in Endangered Species of Wild Flora and Fauna (CITES). As a result, the species is subject to the Convention, http://www.cites.org/.
Australian legislation: Marine Listed under the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999). http://www.environment.gov.au/epbc/species/marine.html

Some authors consider H. tristis to be a synonym of H. kelloggi, a larger species not found in Australian waters.

H. tristis is most similar to H. taeniopterus, differing primarily in having a double lowermost shoulder-ring spine and a more distinct and more erect coronet. H. tristis has been misidentified as H. whitei, H. kuda and H. kelloggi. It is readily distinguished from H. whitei by the smaller coronet and position of the uppermost shoulder-ring spine, at the gill opening in H. tristis and near the pectoral-fin base in H. whitei. H. kuda and H. kelloggi are not found in Australian waters.

From the Greek ippos = horse and kampe = curvature. The specific name tristis is Latin for sad, in reference to the spotting around the eyes which resemble tears.

Hippocampus tristis Castelnau 1872, Proc. Zool. Acclim. Soc. Vict. 1: 197, Melbourne markets.

Bray, D.J. 2019

Australian Faunal Directory