Denise' Pygmy Seahorse, Hippocampus denise Lourie & Randall 2003
Denise's Pygmy Seahorse, Hippocampus denise, in the Rowley Shoals off north Western Australia, October 2020. Source: Glen Whisson / iNaturalist.org. License: CC By Attribution-NonCommercial
This tiny master of camouflage is less than 2 cm in length, and exactly matches the branches and polyps of its gorgonian sea fans hosts. Denise’s Pygmy Seahorse is orange with a relatively thin body covered in bumps, a long neck, a short snout and a long prehensile tail.
The species are extremely well-camouflaged on their octocoral hosts, gorgonian seafans.
Footage of Denise’s Pygmy Seahorse on the gorgonian Annella reticulata at a depth of 102 metres on Osprey Reef in the Coral Sea, May 2011, taken by the PICASSO-1 ROV from JAMSTEC.
Fabulous footage of Denise' Pygmy Seahorse courtship, mating and birth of baby seahorses.
Denise' Pygmy Seahorse, Hippocampus denise Lourie & Randall 2003
More Info
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Distribution |
Rowleys Shoals, Western Australia (depth 20-25 m), and Holmes Reef and Osprey Reef in the Coral Sea, ENE of Cairns. A specimen at Holmes Reef was collected from a species of the gorgonian octocoral, Villogorgia by an underwater remotely operated vehicle (ROV) at a depth of about 100 metres (elsewhere at depths of 13-90 metres). Elsewhere, the species is widespread in the Western Pacific: Thailand, Malaysia, the Philippines, Indonesia, Papua New Guinea, the Solomon Islands, Vanuatu and Micronesia. Monogamous pairs occur on the gorgonian octocorals: Annella reticulata, Muricella spp., Echinogorgia spp., Verrucella spp., Acanthogorgia spp., Melithaea spp., Villogorgia spp. and Ellisella spp., at depths to 102 m. |
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Features |
Dorsal fin 13-14; Pectoral fin 10-11; Anal fin; Trunk rings 12; Tail rings 27-31. |
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Size |
To 16.2 mm |
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Colour |
Plain orange or orange with dark flecks, and slightly darker bands around the tail. |
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Biology |
The sexes are separate, and the species is mostly monogamous, although polyandry has also been observed (Smith 2010). Males carry the eggs in a brood pouch on the trunk, and give birth to 6-16 live young. Smith & Tibbetts (2008) observed a male giving birth at Wakatobi, Indonesia, after a gestation period of 11 days. "At dawn, the male (18.8 mm SL) emerged from a protected area of the gorgonian and turned outward from the seafan and forcefully expelled six to seven juveniles into the water column) ... The skin of the male was visibly wrinkled following parturition but soon after appeared to have been re-in flated, possibly with seawater. Thirty minutes after the male had given birth, the female transferred a new clutch of eggs. This involved the pair grasping tails, floating free from the gorgonian for several seconds and then the physical connection of the urino-genital openings. Four back-to-back pregnancies of this pair were observed; all births occurred at dawn after a gestation period of 11 days." Video footage shows one male giving birth to 13 darkly pigmented miniature seahorses which floated upwards in the water column. Males and females perform a courtship ritual before the female transfers her eggs to the male's brood pouch. Following settlement, juveniles remain in small mixed-sex groups on the gorgonian on which they settled. |
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Conservation |
CITES: listed in Appendix II of CITES in 2004 IUCN: listed as DATA DEFICIENT. |
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Similar Species |
Differs from the Pygmy Seahorse, Hippocampus bargibanti, in having a smoother body with fewer polyp-like tubercles; females are also more slender and elongate, whereas males are more rounded. |
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Etymology |
The species is named in honour of Denise Tackett, who first brought it to the notice of the authors, and has spent hundreds of hours underwater observing the behaviour of pygmy seahorses, especially Hippocampus bargibanti. The name “Denise” also means “follower of Dionysus, the Greek god of wine; wild, frenzied”, and H. denise is more active than H. bargibanti (Lourie & Randall 2003). |
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Species Citation |
Hippocampus denise Lourie & Randall 2003, Zool. Stud. 4(2): 286, Figs. 2, 4a, 4b, 5, 6-10. Type locality: Banta Island, Nusa Tenggara, Indonesia, 8°24'S, 119°17'E, depth 26 m. |
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Author |
Bray, D.J. 2020 |
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Resources |
Denise' Pygmy Seahorse, Hippocampus denise Lourie & Randall 2003
References
Foster, R., Bridge, T.C.L. & Bongaerts, P. 2012. The first record of Hippocampus denise (Syngnathidae) from Australia. aqua, International Journal of Ichthyology 18(1): 55 -57.
Gomon, M.F. & Kuiter, R.H. 2009. Two new pygmy seahorses (Teleostei: Syngnathidae: Hippocampus) from the Indo-West Pacific. Aqua, International Journal of Ichthyology 15(1): 37-44.
Heard, J., Chen, J.-P. & Wen, C.K.C. 2019. Citizen science yields first records of Hippocampus japapigu and Hippocampus denise (Syngnathidae) from Taiwan: A hotspot for pygmy seahorse diversity. ZooKeys 883: 83-90. https://doi.org/10.3897/zookeys.883.39662
Kuo, T.-C. & Pollom, R. 2017. Hippocampus denise. The IUCN Red List of Threatened Species 2017: e.T41716A54909161. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T41716A54909161.en. Downloaded on 15 September 2019.
Lourie, S.A. & Kuiter, R.H. 2008. Three new pygmy seahorse species from Indonesia (Teleostei: Syngnathidae: Hippocampus). Zootaxa 1963: 54-68. https://doi.org/10.11646/zootaxa.1963.1.4
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. & Randall, J.E. 2003. A new pygmy seahorse, Hippocampus denise (Teleostei: Syngnathidae) from the Indo-Pacific. Zoological Studies 42(2): 284-291. See ref online
Nishikawa, J., Fitzpatrick, R., Reimer, J.D., Beaman, R.J., Yamamoto, H. & Lindsay, D.J. 2011. In situ observation of Denise’s pygmy seahorse Hippocampus denise associated with a gorgonian coral Annella reticulata at Osprey Reef, Australia. Galaxea, Journal of Coral Reef Studies 13(1): 25-26. https://doi.org/10.3755/galaxea.13.25
Reijnen B.T., van der Meij, S.E.T. & van Ofwegen, L.P. 2011. Fish, fans and hydroids: host species of pygmy seahorses. ZooKeys 103: 1-26. https://doi.org/10.3897/zookeys.103.953
Short, G., Smith, R., Motomura, H., Harasti, D. & Hamilton, H. 2018 See ref. online Hippocampus japapigu, a new species of pygmy seahorse from Japan, with a redescription of H. pontohi (Teleostei, Syngnathidae). ZooKeys 779: 27-49. https://doi.org/10.3897/zookeys.779.24799
Short, G., Claassen L, Smith, R., Brauwer, M., Hamilton, H., Stat, M. & Harasti, D. 2020. Hippocampus nalu, a new species of pygmy seahorse from South Africa, and the first record of a pygmy seahorse from the Indian Ocean (Teleostei, Syngnathidae) ZooKeys 934: 141-156. https://doi.org/10.3897/zookeys.934.50924
Smith, R.E. 2010. The biology and conservation of gorgonian-associated pygmy seahorses PhD Thesis, School of Biological Sciences, The University of Queensland. 162 pp.
Smith, R.E. & Tibbetts, I.R. 2008 Mating and birth of Denise’s pygmy seahorses (Hippocampus denise) observed in the wild. Coral Reefs 27: 617. https://doi.org/10.1007/s00338-008-0373-8
Smith, R.E., Grutter, A.S. & Tibbetts, I.R. 2012. Extreme habitat specialisation and population structure of two gorgonian-associated pygmy seahorses. Marine Ecology Progress Series 444: 195-206. https://doi.org/10.3354/meps09471
