Family Syngnathidae

Syngnathidae

Taxonomy: A large family with more than 230 recognised species in over 50 genera. In Australian waters currently 120 species in 40 genera are recognised.

Distribution, ecology and habitat: Worldwide, mostly in marine tropical to warm temperate waters in depths usually between 1-100 metres, usually in the upper 50 m; some species have been trawled in deeper shelf and upper slope waters, and several live in estuarine and freshwater environments. Syngnathids are mostly benthic on coastal reefs, living an a range of habitats including marine algal and seagrass beds, sandy and rubble substrates and in caves and crevices. A few species are found offshore amongst floating Sargassum algae.

Characteristics:
Meristics: D 7-64; A 0-6; P 0-26; C 0-11; Body rings: abdominal 8-28 + caudal 14-91; BR 1-3; Circumorbital bones 2-3.
Head and body: Body typically elongate, snout tubular; gill opening a small pore in the opercular membrane. Seahorses differ from most other syngnathids in having the head at a 90° angle to the body axis and a distinctly prehensile tail with which they cling to the substrate.
Fins: Fin spines absent, pelvic fins absent; other fins are variously present, absent or reduced.
Body covering: Scales absent; body encased in a series of bony rings.

Size: Range in size from about 10 mm (pygmy seahorses) to about 650 mm.

Food and feeding: Carnivorous, feeding primarily on small benthic and pelagic crustaceans, including copepods, amphipods, mysids and shrimps.

Reproduction and early life history: Oviparous, sexes separate. Males and females may occupy small home ranges and often live in pairs. Females deposit their eggs in a brood pouch or on a modified brood area on the underside of the male, where they are fertilized, incubated and nourished by the male until the young hatch.
Eggs: Eggs spherical except Hippocampus, which appear ellipsoidal or pear-shaped.
Larvae: Planktonic, larvae and postlarvae resemble miniature adults.
Juveniles: Often remain in the plankton for extended periods.

Fisheries: Although most species have no commercial importance, seahorses in particular are traded worldwide for use in the Traditional Chinese Medicine (TCM) industry, as popular aquarium fishes or are simply dried and sold as curios. Overfishing has lead to the decline of some shallow water species. Various species are now bred in captivity in the aquaculture industry.

Conservation status: All Hippocampus species and some other syngnathids are on the IUCN List of Threatened Species http://www.iucnredlist.org/search/

In 2004, seahorses were listed on Appendix II of CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora). Therefore, in those countries which are signatory to the Convention, the export of seahorses must not be detrimental to wild seahorse populations.

Australian Legislation: All syngnathid species are listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999.

State fisheries legislation protecting syngnathid species includes the Victorian Fisheries Act 1995 which lists all syngnathids as Protected Aquatic Biota and the Tasmania Living Marine Resources Management Act 1995 which prohibits the take of all syngnathid species in Tasmanian waters without a permit.

Remarks: Many seahorse and pipefish species form monogamous pairs and some perform daily greeting rituals during the breeding season.

Australian species:

References:

Ashley-Ross, M.A. 2002. Mechanical properties of the dorsal fin muscle of seahorse (Hippocampus) and pipefish (Syngnathus). J. Exp. Zool. 293: 561-577.

Casey, S.P., H.J. Hall, H.F. Stanley & A.C.J. Vincent. 2004. The origin and evolution of seahorses (genus Hippocampus): a phylogenetic study using the cytochrome b gene of mitochondrial DNA. Mol. Phylo. Evol. 30: 261-272.

Carcupino, M., A. Baldacci, M. Mazzini & P. Franzoi. 2002. Functional significance of the male brood pouch in the reproductive strategies of pipefishes and seahorses: a morphological and ultrastructural comparative study on three anatomically different pouches. J. Fish Biol. 61: 1465-1480.

Consi, T.R., P.A. Seifert, M.S. Triantafyllou & E.R. Edelman. 2001. The dorsal fin engine of the seahorse (Hippocampus sp.). J. Morphol. 248: 80-97.

Dawson, C.E. 1985. Indo-Pacific Pipefishes (Red Sea to the Americas). Gulf Coast Research Laboratory, Ocean Springs (Mississippi), 230 pp., 239 figs.

Dawson, C.E. 1994. Family Syngnathidae. (pp. 440-475) In Gomon, M.F., J.C.M Glover, & R.H. Kuiter. (eds.) The Fishes of Australia's South Coast. State Print, Adelaide, 992 pp. 810 figs.

Foster, S.J. & A.C.J. Vincent. 2004. Life history and ecology of seahorses: implications for conservation and management. J. Fish Biol. 65: 1-61.

Foster, S.J. & A.C.J. Vincent. 2005. Enhancing sustainability of the international trade in seahorses with a single minimum size limit. Conservation Biology 19: 1044-1050.

http://HippocampusInfo.org/

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

Hoffman, E.A., K.B. Mobley & A.G. Jones. 2006. Male pregnancy and the evolution of body segmentation in seahorses and pipefishes. Evolution 60: 404-410.

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Kvarnemo, C. & L.W. Simmons. 2004. Testes investment and spawning mode in pipefishes and seahorses (Syngnathidae). Biol. J. Linn. Soc. 83: 369-376.

Kuiter, R.H. 1996. Guide to Sea Fishes of Australia. New Holland Press, Sydney. 433 pp. figs.

Kuiter, R. H. 2001. Revision of the Australian Seahorses of the genus Hippocampus (Syngnathiformes: Syngnathidae) with descriptions of nine new species Rec. Aust. Mus. 53: 239-340

Kuiter, R.H. 2000. Seahorses, Pipefish and their Relatives, a comprehensive guide to Syngnathiformes. TCM Publishing, Chorleywood, UK. 237 pp.

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, 214 pp.

Nelson, J.S. 2006. Fishes of the World. 4th  Ed. John Wiley & Sons, Inc., Hoboken, New Jersey. 601 pp.

Paulus, T. 1999.  Family Syngnathidae. p.2264-2276 In Carpenter, K.E. & V.H. Niem (eds.) The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. FAO, Rome, Vol 4.

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. Environment Australia, Canberra. 375 pp.

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Ripley, J.L. & C.M. Foran. 2006. Placental transfer - its not just for mammals anymore. Mar. Environ. Res. 62: S268-S269.

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Teske, P.R., M.I. Cherry & C.A. Matthee. 2004. The evolutionary history of seahorses (Syngnathidae: Hippocampus): molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean. Molecular Phylogenetics and Evolution 30: 273-286.

Teske, P.R., H. Hamilton, P.J. Palsboll, C.K. Choo, H. Gabr, S.A. Lourie, M. Santos, A. Sreepada, M.I. Cherry & C.A. Matthee. 2005. Molecular evidence for long-distance colonization in an Indo-Pacific seahorse lineage. Marine Ecology-Progress Series 286: 249-260.

Vincent, A.C.J. 1994. Seahorses exhibit conventional sex roles in mating competition, despite male pregnancy. Behaviour 128: 135-151.

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Wilson, T.B., I. Ahnesjö, 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: 1374-1386.

Wilson, A. B., A. Vincent, I. Ahnesjö & A. Meyer. 2001. Male pregnancy in seahorses and pipefishes (Family Syngnathidae): Rapid diversification of paternal brood pouch morphology inferred from a molecular phylogeny. Journal of Heredity 92: 159-166.