Bighead Seahorse, Hippocampus grandiceps Kuiter 2001

Other Names: Big-head Seahorse

A Bighead Seahorse, Hippocampus grandiceps. Source: Rudie Kuiter / Aquatic Photographics. License: All rights reserved


This very spiny seahorse is only found in the Gulf of Carpentaria.

Cite this page as:
Dianne J. Bray & Vanessa J. Thompson, Hippocampus grandiceps in Fishes of Australia, accessed 24 May 2024,

Bighead Seahorse, Hippocampus grandiceps Kuiter 2001

More Info


taken as bycatch in prawn trawls


Endemic to tropical northern Australia on the eastern side of the Gulf of Carpentaria, Queensland. The Bighead Seahorse lives on soft bottom habitats is depths of 10-12 m.


Meristic features: Dorsal fin 18; Pectoral fin 17-18 (usually 18); trunk rings 11; tail rings 32-33; subdorsal rings 2 + 1.
Head and body: Head long, about equal to trunk length, angled down to near trunk; snout long, almost half head length.
Spines and tubercles: Body very spinous; spine above eye perpendicular to snout, equal to pupil diameter; nasal spine angular, directed forward 45° to snout; nape spine equal to pupil diameter, directed somewhat forward; spine behind eye of moderate length; double spines below eye; shoulder-ring spines long, uppermost and central spines at levels with either ends of pectoral-fin base, lowermost double, anterior barb smaller and directed forward; lateral head spine moderately long; superior trunk ridge with short spines, slightly enlarged at regular intervals from 1st ring to below dorsal fin base; lateral ridge with spines on 2nd to 10th ring, those on rings 2, 4, and 6-10 enlarged; inferior trunk ridge with series of spines from 4th to 11th ring, progressively from short to long; ventral trunk ridge with downward angled spines in females and scalloped edge in males; superior tail ring spines moderately long from 2nd to 14th ring, becoming progressively smaller posteriorly.
Coronet: Coronet of moderate height with 5 short and sharp diverging spines at apex.
Lateral line: Lateral line with small indistinct pores, increasingly becoming more difficult to detect posteriorly, reaching 21st tail ring.


Height to 105 mm.


Colour in life unknown. In preservative - pale brownish-grey with pale saddle-like areas on trunk and tail. Snout with distinct dusky barring along entire length.


Like other seahorses, this species presumably feeds by sucking small crustaceans and other planktonic organisms into its mouth.


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.


Of no interest to fisheries. Although taken as bycatch in the Northern Prawn Fishery, there is no known trade in this species for the aquarium or Traditional Medicine industries.


International: Listed under Appendix II of the Convention on the International Trade in Endangered Species of Wild Flora and Fauna (CITES).
Australian legislation: Marine Listed under the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999).


The angled head, body patterns and shallow depth range of H. grandiceps suggest that it may inhabit more weedy areas than those populated by most other species with prominent spines.

Similar Species

H. grandiceps is most similar to H. multispinus, differing in its smaller size, in having shorter spines and males lacking elongate spines over the superior trunk ridge anterior to the dorsal fin.


From the Greek, ippos = horse and kampe = curvature. The specific name grandiceps is from the Latin grandis meaning large or great, and -ceps from the Latin caput meaning head, in reference to the large head of this species.

Species Citation

Hippocampus grandiceps Kuiter 2001, Rec. Aust. Mus. 53: 335, fig 50, West Booby Island, Gulf of Carpentaria, Queensland.


Dianne J. Bray & Vanessa J. Thompson

Bighead Seahorse, Hippocampus grandiceps Kuiter 2001


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 Part 1, 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.

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.

Quick Facts

CAAB Code:37282126

Biology:Males brood the eggs

Depth:10-12 m


Habitat:Soft bottom

Max Size:Height 10.5 cm


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Species Maps

CAAB distribution map