White's Seahorse, Hippocampus whitei Bleeker 1855

Other Names: Common Sea-horse, High Crown Seahorse, Highcrown Seahorse, High-crown Seahorse, New Holland Seahorse, Sydney Seahorse, Whites Seahorse

White's Seahorse, Hippocampus whitei, in southern Queensland. Source: Dave Harasti / http://www.daveharasti.com/. License: All rights reserved


A variably coloured yellow to brown to greyish seahorse, usually with numerous pale flecks. White's Seahorse is locally abundant in Port Stephens and Sydney Harbour.

Video of a White's Seahorse dad giving birth to his offspring in Nelson Bay, Port Stephens, New South Wales.

Cite this page as:
Bray, D.J. & Thmopson, V.J. 2020, Hippocampus whitei in Fishes of Australia, accessed 10 Dec 2023, https://fishesofaustralia.net.au/Home/species/1538

White's Seahorse, Hippocampus whitei Bleeker 1855

More Info


Endemic to eastern Australia, from north of Mackay, Queensland, to Sussex Inlet, New South Wales. Records from elsewhere (Gulf of Carpentaria, Victoria, South Australia, New Guinea, western Indian Ocean and Vanuatu) are based on mis-identifications. The southerly records are of juveniles associating with drifting macroalgae.

Inhabits estuaries, bays and harbours, living in association with seagrass beds, macroalgae, soft corals, gorgonians, sponges, piers, jetties, and the netting enclosing seaside pools.


Dorsal fin 16-19; Anal fin 4; Pectoral fin 13-18; Trunk rings 11; Tail rings 33-35; Subdorsal rings 2 + 1.

Head length about 90% of trunk length; snout length almost half head length; trunk length about one-third height; tail length about two-thirds height.

Spine above eye of moderate size; nape spine small; shoulder-ring spines of moderate size in 3 locations, one near each end of pectoral-fin base but none at gill-opening, lowermost spine double with sub-equal spines; lateral head spine low; body tubercles of small to moderate size along dorsal and lateral ridges, some enlarged and pointed, especially on eighth trunk ring, below dorsal fin and on following part of superior tail ridges; neck-ridge spines absent.

Coronet moderate to tall in height, angled back, spines small and blunt in young, further reduced in large adults, arranged in five-point star at apex, with additional 2 or more small spines anteriorly on base.


Height to about 150 mm, commonly to 200 mm TL.


In life, overall pale to dark brown and almost black, with fine pale spots or striations; sometimes entirely yellow; often saddle-like markings at the first, fourth and eighth trunk rings, and on tail rings where spines are enlarged; snout finely barred with dusky lines dorsally, lines broader near eyes; nasal spine and adjacent area pale.


Feeds on small crustaceans and  zooplankton.


The sexes are separate, and females are egg-layers. The female uses an ovipositor to transfer her eggs into an elaborate enclosed pouch under the abdomen of the male. He male not only fertilizes the eggs inside the pouch and provides physical protection for the developing embryos, but also osmoregulates and aerates the embryos and may provide some nourishment until the offfspring are born.

Each male may brood 100-250 embryos. Following a gestation period of about 3 weeks, up to 150 independent young are born, usually at night. Larger females produce more eggs. Egg diameter 1.8 mm. Males rear several broods each season and often mate again within several days of giving birth.

There is no pelagic larval phase, and the young are morphologically similar to the adults at birth. Newborns are about 8.5 mm long.

Males may have up to seven broods during the breeding season and may mate again the following day after giving birth.


White's Seahorse is protected throughout its range and the collection of individuals is not permitted.


  • NSW Fisheries Management Act 1994 : Endangered
  • EPBC Act 1999 : Marine Listed
  • IUCN Red List : Endangered
  • CITES : Listed under Appendix II 
In recent years, populations have declined in Port Stephens and Sydney Harbour. White's Seahorse is threatened by habitat loss and pollution.


Males and females form monogamous pairs the breeding season from spring to autumn. Individuals live in small overlapping home ranges. Each morning while the male is ‘pregnant', partners greet each other and the female performs a greeting ritual. Courtship behaviour may last up to 9 hours.

Similar Species

H. whitei has been misidentified as  H. tristis, H. procerus (a junior synonym) and H. breviceps. H. tristis and H. breviceps both differ from H. whitei in having the upper shoulder-ring spine near the gill-opening rather than the pectoral-fin base.


The species is named in honour of John White, surgeon-general of the First Fleet and author of Journal of a Voyage to New South Wales 1789, in which a portrait of H. whitei is published.

Species Citation

Hippocampus whitei Bleeker 1855, Verh. Akad. Amsterdam 2: 17. Type locality: Sydney District, New South Wales, Australia.


Bray, D.J. & Thmopson, V.J. 2020


Atlas of Living Australia

White's Seahorse, Hippocampus whitei Bleeker 1855


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Clynick, B.G. 2008. Harbour swimming nets: a novel habitat for seahorses. Aquatic Conservation: Marine and Freshwater Ecosystems 18: 483–492.

Edgar, G.J. 2008. Australian Marine Life: the plants and animals of temperate waters. Sydney : Reed New Holland 2nd edn, 624 pp.

Gomon, M.F. 1997. A remarkable new pygmy seahorse (Syngnathidae Hippocampus) from south-eastern Australia, with a redescription of H. bargibanti Whitley from New Caledonia. Memoirs of Museum Victoria 56(1): 245-253.

Gomon, M.F., Glover, C.J.M. & Kuiter, R.H (eds) 1994. The Fishes of Australia's South Coast. Adelaide : State Printer 992 pp. 810 figs.

Grant, E.M. 1975. Guide to Fishes. Brisbane : Queensland Government, Co-ordinator General’s Department 640 pp.

Harasti, D. 2014. The biology, ecology, and conservation of White's Seahorse Hippocampus whitei. PhD Thesis, School of Environment, University of Technology, Sydney. 223 pp. 

Harasti, D. 2016. Declining seahorse populations linked to loss of essential marine habitats. Marine Ecology Progress Series 546(2015): 173-181.

Harasti, D., Glasby, T.M. & Martin-Smith, K.M. 2010. Striking a balance between retaining populations of protected seahorses and maintaining swimming nets. Aquatic Conservation: Marine and Freshwater Ecosystems 20: 159–166.

Harasti, D., Martin-Smith, K. & Gladstone, W. 2012. Population dynamics and life history of a geographically restricted seahorse, Hippocampus whitei. Journal of Fish Biology 81(4): 1297-1314.  

Harasti, D., Martin-Smith, K. & Gladstone, W. 2014. Ontogenetic and sex-based differences in habitat preferences and site fidelity of White's seahorse Hippocampus whitei. Journal of Fish Biology 85(5): 1413-1428.  

Harasti, D., Martin-Smith, K. & Gladstone, W. 2014. Does a no-take marine protected area benefit seahorses? PLOS One 9(8): e105462.

Harasti, D. & Pollom, R. 2017. Hippocampus whitei. The IUCN Red List of Threatened Species 2017: e.T10088A46721312. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T10088A46721312.en. Downloaded on 02 July 2020.

Hellyer, C.B., Harasti, D. & Poore, A.G. B. 2011. Manipulating artificial habitats to benefit seahorses in Sydney Harbour. Aquatic Conservation: Marine and Freshwater Ecosystems 21: 582–589.

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

Kuiter, R.H. 2001. Revision of the Australian Seahorses of the genus Hippocampus (Syngnathiformes: Syngnathidae) with descriptions of nine new species. Records of the Australian Museum 53: 293-340. (described as Hippocampus procerus)

Kuiter, R.H. 2009. Seahorses and their relatives. Seaford, Australia : Aquatic Photographics 331 pp. (as H. whitei and  H. procerus)

Lourie, S.A., Pollom, R.A. & Foster, S.J.  2016. A global revision of the seahorses Hippocampus Rafinesque 1810 (Actinopterygii: Syngnathiformes): taxonomy and biogeography with recommendations for further research. Zootaxa 4146(1): 1-66. https://doi.org/10.11646/zootaxa.4146.1.1

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

Manning, C.G., Foster, S.J., Harasti, D. & Vincent, A.C.J. 2018. A holistic investigation of the ecological correlates of abundance and body size for the endangered White's seahorse Hippocampus whitei. Journal of Fish Biology 93: 649– 663. https://doi.org/10.1111/jfb.13745

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Simpson, M., Coleman, R.A., Morris, R.L. & Harasti, D. 2020. Seahorse Hotels: Use of artificial habitats to support populations of the endangered White's seahorse Hippocampus whitei, Marine Environmental Research 157: 104861, https://doi.org/10.1016/j.marenvres.2019.104861

Simpson, M., Morris, R.L., Harasti, D. & Coleman, R.A. 2019. The endangered White’s Seahorse Hippocampus whitei chooses artificial over natural habitats. Journal of Fish Biology 1-7. https://doi.org/10.1111/jfb.14002

Simpson, M., Morris, R.L., Harasti, D. & Coleman, R.A. 2020. Swimming nets have positive effects on populations of the endangered White's seahorse Hippocampus whitei. Aquatic Conservation: Marine and Freshwater Ecosystems: 1– 14. https://doi.org/10.1002/aqc.3451

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Quick Facts

CAAB Code:37282027

Biology:Males brood the eggs

Conservation:IUCN Endangered

Depth:1-25 m

Habitat:Reef associated

Max Size:17cm


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