Few sea creatures have the universal appeal of the seahorse, one of nature’s true oddities. To many people the only connection between a seahorse and the fish from the local market is that both are found in the ocean. Yet not only are these seemingly mythical creatures fish, but they belong to the largest family of fishes found in the coastal waters of Southern Australia.
A preserved Potbelly Seahorse, Hippocampus abdominali
Source: Museum Victoria
Seahorses are part of a much larger group of animals (the family Synganthidae) which have thick, external armour encasing the body and a tubular snout tipped with a mouth designed like a hatch door. The family also includes pipefishes, pipehorses and seadragons.
Pipefishes are generally long and pencil-like in shape, with a straight, tapering tail. Seahorses have a prehensile tail and a thickened body. The smallest adult seahorses are less than a centimetre long. Pipehorses (genus Solegnathus) are so-named because they have a typical pipefish-shaped head and body, along with the prehensile tail of a seahorse. They are largest fishes in the family, with one species growing to 50 cm in length. The family also includes such iconic Australian species as the Leafy Seadragon Phycodurus eques and Weedy Seadragon Phyllopteryx taeniolatus which is Victoria’s marine emblem.
Weedy Seadragon, Phyllopteryx taeniolatus
Photographer: Rudie Kuiter / Source: Aquatic Photographics
After a sometimes elaborate courtship, syngnathids reproduce in an unusual way. The female transfers her eggs to the male, who fertilizes and then broods them until they hatch.
Although not all species incubate their eggs in a pouch like that on the belly of the male seahorse, they all retain their eggs somewhere on the underside of their body until they hatch. The eggs are either partly enclosed in a pouch or simply attached to the underside of the tail until they hatch.
Most pipefishes, seahorses and seadragons live in shallow bays and coastal waters, especially amongst weed-covered reefs or in seagrass meadows, where they are masters of camouflage. Being rather poor swimmers, they are often found washed up on beaches after storms – many a beachcomber has discovered a dead seahorse or seadragon in the course of a daily walk along their favourite beach.
Spotted Pipefish, Stigmatopera argus
Photographer: Rudie Kuiter / Source: Aquatic Photographics
Protecting seahorses and their relatives
With our increasing awareness of the affect of human practices on the marine environment and the animals living in it, measures (including protective legislation) have been taken to assist with its survival. Seahorses have long been considered by certain cultures to have special medicinal properties and have been collected commercially for this purpose. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) enacted rules in May 2004 means that any country wishing to export seahorses will have to demonstrate that no wild populations are harmed by the global trade in seahorses.
In Australia, laws have been passed to reduce the exploitation of seahorses and their close relatives for this trade. All seahorses, pipefishes, pipehorses and seadragons are protected in Victorian waters.
A preserved Pipehorse, Solegnathis spinossismus
Source: Museum Victoria
Further Reading
Kuiter, Rudie. 2000. Seahorses, Pipefishes and their relatives: A comprehensive guide to Syngnathiformes. TMC Publishing: Chorleywood, UK.
Dawson, C. E. 1985. Indo-Pacific Pipefishes (Red Sea to the Americas). Gulf Coast Research Laboratory, Ocean Springs: Mississippi, USA.
Paxton, J. R. and Eschmeyer, W.N. (Eds). 2003. Encyclopedia of Fishes. 3rd Edition. Fog City Press, San Francisco.
Gomon, M. F., Glover, C. J. M. and Kuiter, R. H. (eds) 1994. Fishes of Australia's South Coast. Handbook of the Flora and Fauna of South Australia. State Print: Adelaide.