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Knobby Seahorse Hippocampus tuberculatus Castelnau, 1875
[CAAB 37 282116]

Distribution Map see an interactive map here (new window)

The Knobby Seahorse occurs only in tropical Western Australia and may be found floating amongst Sargassum algae or attached to sponges. The large red tubercles on the back and tail provide camouflage from predators.

Distribution, ecology and habitat:

Endemic to temperate and tropical Western Australia, from about Fremantle to Onslow; benthic inshore species, juveniles and sub-adults often float offshore in Sargassum algae, while adults usually inhabit sponge reefs to 20 m.

Size:

Height to 75 mm.

Food and feeding:

Likely to feed on epibenthic invertebrates such as amphipods, caridean shrimp and peracarids.

Reproduction and early life history:

Reproduction: Sexes separate, reproduction a form of viviparity or ovoviviparity, whereby the 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.
Eggs: Not described.
Larvae: Not described.

Characteristics:

Meristics: D 20-21; A 4; P 14-15; trunk rings 11; tail rings 36-37; subdorsal rings 3 + 1.
Head and body: Trunk short, head moderately large, snout short (proportionally longest in young and sub-adults).
Spines and tubercles: Body spines well-developed; moderately long spine above eyes, with secondary smaller spine anteriorly at base, similar in shape to nasal ridge; small spine behind eye; large lateral head spine; nape spine of moderate size, directed upward; 2 separate low angular spines below eye; 3 moderate to long spines on shoulder ring, uppermost at gill-opening, central spine at level of last pectoral-fin ray, and lowermost largest and recurving; neck ridge with 2 small spines; superior trunk ridge with blunt rounded spines of moderate size, enlarged on rings 1, 3, 5, and subdorsally; lateral trunk ridge with enlarged spines on rings 3, 5, and 7; inferior trunk ridge with last 3 spines enlarged; ventral trunk with low downward directed spines; superior tail ridge with enlarged spines up to about eye-size on every 2^nd or 3^rd ring, becoming gradually smaller posteriorly; inferior tail ridge a continuation of trunk ridge, with spines gradually reducing in size. adults with large tubercles on back and tail.
Coronet: Coronet tall and angled back, square to rounded in cross section, without spines on corners, but with small central spine on apex, spine angled upward in young, becoming smooth and rounded in mature adults.
Lateral line: Lateral line well developed with pores on low-tubes, visible to about 28^th tail ring.

Colour:

Colour variable depending on habitat. Specimens from floating Sargassum dark brown to blackish with a well defined white area over interorbital extending to base of coronet and tip of snout. Adults on rocky reefs mostly yellow to brown, with a white area over front of head; operculum with black spots; tubercles over back often bright red. In preservative - mainly brown; some with fine black spots on operculum or below dorsal-fin base.

Similar species:

Similar to H. breviceps from temperate south-eastern Australia, differing in being generally more spiny overall and in having an angular nose ridge and double spines above each eye.

Fisheries:

None. There is no known trade in this species in the aquarium or Asian Traditional Medicine industries.

Conservation Status:

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/.
Listed (as a synonym of H. breviceps) as Data Deficient on the 2007 IUCN Red List of Threatened species. http://www.iucnredlist.org/search/details.php/10063/summ
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

Remarks:

Considered by some authors to be a synonym of H. breviceps.

Other common names:

None

Original citation:

Hippocampus tuberculatus Castelnau 1875, Research. Fish. Australia 2: 48, Swan River, Western Australia.

Etymology:

From the Greek ippos = horse and kampe = curvature. The specific name tuberculatus is from the Latin tuber meaning swelling, in reference to the large tubercles on the back and tail of the adults.

References:

Castelnau, F.L. 1875. Researches on the fishes of Australia. Philadelphia Centennial Expedition of 1876. Intercolonial Exhibition Essays, 1875-6. Research. Fish. Australia 2: 1-52.

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.

Kuiter, R.H. 2000. Seahorses, Pipefishes and their Relatives. TMC Publishing, Chorleywood, UK, 240 pp.

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.

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.

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.