Family SYNGNATHIDAE

Common name: Seahorses, pipefishes, seadragons, pipehorses

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Summary:

A large and diverse group of pipefishes, seahorses, seadragons and pipehorses, all having a tiny mouth at the end of a tubular snout and semi-flexible bodies encased in bony rings. 

Syngnathids lack fin spines and pelvic fins, and other fins may be reduced or absent. They have a unique reproductive mode where the female deposits her eggs into an abdominal brood pouch or onto a modified exposed region on the underside of her male partner. The male then incubates and nourishes the developing embryos until they hatch. 

These extraordinary cryptic fishes are often ornamented with filaments and other appendages to enhance their excellent camouflage.

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Cite this page as:
Bray, D.J. 2021, Seahorses, pipefishes, SYNGNATHIDAE in Fishes of Australia, accessed 18 Apr 2024, https://fishesofaustralia.net.au/Home/family/34

More Info

Family Taxonomy

 A large family with more than 340 recognised species in more 50 genera. In Australian waters about species in 40 genera are recognised.

Family Distribution

Syngnathids are found worldwide in marine tropical to temperate waters, mostly in depths above 50 m. Some species are trawled in deeper shelf and upper slope waters, and several live in estuarine and freshwater environments.

Syngnathids are mostly benthic on coastal reefs, amongst marine algae and seagrass beds, or on sandy and rubble substrates and in caves and crevices. A few species are found offshore amongst floating Sargassum algae.

Family Description

Meristic features: Dorsal fin 7-64; Anal fin 0-6; Pectoral fin 0-26; Caudal 0-11; Body rings: abdominal 8-28 + caudal 14-91; Branchiostegal rays 1-3; Circumorbital bones 2-3.

Body typically elongate, mouth very small at end of a tubular snout; gill opening a small pore in the opercular membrane. Sygnathids lack fin spines and pelvic fins; other fins are variously present, absent or reduced. They are encased in a series of bony rings. 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.

Family Size

 Range in size from less than 10 mm (pygmy seahorses) to about 65 cm, although most species are relatively small.

Family Colour

 Variable in colour pattern and body ornamentation. Most species are cryptically coloured to match their surroundings and many species are adorned with dermal appendages and filaments. Most are extremely well camouflaged, often mimicing seagrasses and algae in their environment.

Family Feeding

Carnivores, feeding primarily on small benthic and pelagic crustaceans, including copepods, amphipods, mysids and shrimps.

Most syngnathids feed by rapidly and powerfully sucking prey items in through their long snouts.

Syngnathids are preyed upon by a wide variety of predators ranging from cephalopods to sharks, rays, bony fishes, sea birds, turtles and marine mammals.

Family Reproduction

The sexes are separate and fertilisation is external. Males and females often live in pairs and may occupy small home ranges.

Many seahorse and pipefishes form monogamous pair bonds and some perform daily greeting rituals during the breeding season. Females deposit their eggs in a brood pouch, or onto a modified brood area on the underside of the male.

The eggs are then fertilised by the male who then incubates and nourishes the developing embryos until the young hatch. Syngnathid eggs are generally spherical except in Hippocampus, which has ellipsoidal or pear-shaped eggs.

The larvae are planktonic, and postlarvae resemble miniature adults. Juveniles often remain in the plankton for extended periods.

Family Commercial

Most species are of no commercial importance, however, over-fishing has led to the decline of some shallow water species. Seahorses in particular are traded worldwide for use in the Traditional Chinese Medicine (TCM) industry and as popular aquarium fishes, or are simply dried and sold as curios. 

A number of species are bred in captivity in for trade in the aquarium industry. Although Australia mainly exports live syngnathids for the aquarium trade, a few kilos of dried sygnathids are exported to Asia.

In Australia, strong legislation at both Commonwealth (national) and State levels protect syngnathids and/or require monitoring of their exploitation. All exports of syngnathids from Australia require permits under approved management plans (Vincent et al. 2011b)

Family Conservation

All Hippocampus species and some other syngnathids are on the IUCN Red List of Threatened Species. 

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

All sygnathid species are listed in Australia as threatened under the Environment Protection and Biodiversity Conservation Act 1999 EPBC Act. Various State Government agencies protect syngnathid species. 

Syngnathids are protected under the Victorian Fisheries Act 1995, the Tasmania Living Marine Resources Management Act 1995 and the South Australian Fisheries Management Act 2007.

Family Remarks

 The fossil record of syngnathids dates back to the Eocene, and the oldest known fossil pipefishes are from Monte Bolca in Italy. In 2005, Miocene seahorse fossils were found in the Tunjice Hills of Slovenia.

Family Biology


Author

 Bray, D.J. 2021

Family Resources

Australian Faunal Directory

References

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