West Australian Seahorse, Hippocampus subelongatus Castelnau 1873

Other Names: Tigersnout Seahorse

Summary:

A well camouflaged seahorse varying in colour from brown, white, red, orange to purple, with a series of thin dark bars on the snout. In early summer, the West Australian Seahorse congregates in the lower reaches of the Swan River and is collected for the live aquarium trade.

Video of the courtship dance of the Western Australian Seahorse.

Cite this page as:

Dianne J. Bray & Vanessa J. Thompson, Hippocampus subelongatus in Fishes of Australia, accessed 18 Apr 2024, https://fishesofaustralia.net.au/home/species/1543

West Australian Seahorse, Hippocampus subelongatus Castelnau 1873

More Info

Distribution	Endemic to subtropical and temperate waters of Western Australia, from about Cape Leeuwin to Shark Bay. Often found amongst macroalgae, sponges adn sea squirts in muddy and silty habitats in sheltered bays, and on jetty pylons and moorings at 1-25 m.
Features	Meristic features: D 18; P 17-18; trunk rings 11; tail rings 33-34; subdorsal rings 2 + 1. Body slender in both sexes, head long, about 85-90% trunk length, snout long and narrow, about half head length; rings thick. Spines and tubercles: Subdorsal spines 3/0,1,0-0.5. Spines on trunk and tail of moderate length in juveniles, becoming blunt with growth and appearing as low tubercles in adults. Nasal spine angular; enlarged tubercles above eyes, laterally on head, and sub-dorsally on trunk; nape spine long when young; shoulder-ring with 3 blunt spines, uppermost just above top of pectoral-fin base, central spine at level of last few rays of pectoral-fin base and lowermost double, in form of short laterally-directed, divergent spines. Coronet tall, crown with 5 spines in star-like arrangement when young, spines becoming blunt and forming rounded flanges in large adults. Lateral line indistinct, pores extending to 22^nd tail ring.
Size	Height to 200 mm.
Colour	In life, colour highly variable from grey, yellow, brown to burgundy-red or purple, usually with thin dark barring on snout; body plain or with dusky striations or reticulations; dorsal surface of trunk edged with a dark vertical line. In preservative - overall pale brown, otherwise patterns similar to those of live individuals.
Feeding	Individuals congregate in the lower reaches of the Swan River during early summer when many crustaceans are spawning, providing food for their offspring. Feed diurnally sucking up small crustaceans and zooplankton drifting past.
Biology	The sexes are separate, and males and females form monogamous pairs during the breeding season. Before spawning, they perform an elaborate courtship ritual for several days. The female then uses her ovipositor to transfer her egg clutch (200-720 eggs) into an elaborate enclosed pouch on the tail of the male. He not only fertilizes the eggs inside the pouch and provides physical protection for the developing embryos, he also osmoregulates and aerates the embryos and provides some nourishment via a pseudoplacenta until his offspring are born. The gestation period usually lasts 2-3 weeks, varying with water temperature. Genetic studies of maternity in male broods have shown that a male H. elongatus receive eggs from only one female for each particular brood, and that some male/female pairs remain monogamous during the breeding season. Brood size up to 720 eggs. The young fend for themselves after birth.
Fisheries	Both wild caught and captive bred H. subelongatus are sold in Australia and exported for the aquarium trade. Reported population declines in the Swan River may be a result of over-collecting, or may be due to seasonal environmental fluctuations.
Conservation	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/. The International trade is monitored through a CITES licensing system and a minimum size of 10 cm applies. IUCN Red List of Threatened species: Data Deficient. http://www.iucnredlist.org/search/details.php/40773/summ EPBC Act 1999: Marine Listed http://www.environment.gov.au/epbc/species/marine.html
Remarks	H. subelongatus occurs seasonally in the lower reaches of the Swan River, moving to deeper waters in winter.
Similar Species	H. subelongatus is most similar to H. angustus, with which it has been confused. H. angustus has a lower coronet with distinct spines, spines on body ridges junctions and occurs northwards from Shark Bay.
Etymology	From the Greek ippos = horse and kampe = curvature. The specific name subelongatus is from the Latin sub- meaning less than and elongatus meaning prolonged, in reference the moderate spine length of this species.
Species Citation	Hippocampus elongatus Castelnau 1873, Proc. Zool. Acclim. Soc. Vict. 2: 144, Fremantle, Western Australia.
Author	Dianne J. Bray & Vanessa J. Thompson

West Australian Seahorse, Hippocampus subelongatus Castelnau 1873

References

Castelnau, F.L. 1873. Contribution to the ichthyology of Australia. Nos. III thru IX. Proc. Zool. Acclim. Soc. Victoria 2: 37-158.

Hoese, D.F., D.J. Bray, J.R. Paxton & G.R. Allen. 2006. Fishes. In Beesley, P.L. & A. Wells. (eds.) Zoological catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia, 2178 pp.

Jones, A.G. & J.C. Avise. 2001. Mating systems and sexual selection in male-pregnant pipefishes and seahorses: insights from microsatellite-based studies of maternity. Am. Genet. Assoc. 92: 150-158.

Jones, A.G., C. Kvarnemo, G.I. Moore, L.W. Simmons & J.C. Avise. 1998. Microsatellite evidence for monogamy and sexbiased recombination in the Western Australian seahorse Hippocampus angustus. Mol. Ecol. 7: 1497-1506.

Jones, A. G., Moore, G. I., Kvarnemo, C., Walker, D. & Avise, J.C. (2003). Sympatric speciation as a consequence of male pregnancy in seahorses. Proceedings of the National Academy of Sciences 100: 6598-6603.

Kvarnemo, C., Moore, G. I. & Jones, A.G. (2006). Sexually selected females in the monogamous Western Australian seahorse. Proceedings of the Royal Society B. 274: 521-525.

Kendrick, A.J. & G.A. Hyndes. 2003. Patterns in the abundance and size distribution of syngnathid fishes among habitats in a seagrass-dominated marine environment. Estuarine and Coastal Shelf Science 57: 631-640.

Kvarnemo, C., G.I. Moore, A.G. Jones, W.S. Nelson & J.C. Avise. 2000. Monogamous pair bonds and mate switching in the Western Australian seahorse Hippocampus subelongatus. J. Evol. Biol. 13: 882-888.

Kuiter, R.H. 2000. Seahorses, Pipefishes and their Relatives. TMC Publishing, Chorleywood, UK, 240 pp. (as Hippocampus elongatus)

Kuiter, R.H. 2001. Revision of the Australian Seahorse of the genus Hippocampus (Syngnathiformes: Syngnathidae) with descriptions of nine new species. Rec. Aust. Mus. 53: 293-340. (as Hippocampus elongatus)

Kuiter, R.H. 2009. Seahorses and their relatives. Seaford, Australia : Aquatic Photographics pp. 331.

Lourie, S.A., A.C.J. Vincent & H.J. Hall. 1999. Seahorses: an identification guide to the world's species and their conservation. Project Seahorse. London, UK, 214 pp.

Martin-Smith, K.M. & A.C.J. Vincent. 2006. Exploitation and trade of Australian seahorses, pipehorses, sea dragons and pipefishes (Family Syngnathidae). Oryx 40(2): 141-151.

Payne, M.F. & R.J. Rippingale. 2000. Rearing West Australian seahorse, Hippocampus subelongatus, juveniles on copepod nauplii and enriched Artemia. Aquaculture 188: 353-361.

Pogonoski, J.J., D.A. Pollard & J.R. Paxton. 2002. Conservation Overview and Action Plan for Australian Threatened and Potentially Threatened Marine and Estuarine Fishes. Canberra, Environment Australia, 375 pp.

Project Seahorse 2002. Hippocampus subelongatus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. . Downloaded on 26 September 2013.

Wilson, A.B, I. Ahnesjo, A.C.J. Vincent & A. Meyer. 2003. The dynamics of male brooding, mating patterns, and sex roles in pipefishes and seahorses (family syngnathidae). Evolution 57(6): 1374-1386.