Sea Horses Stay the Course

But Scientists Face Hurdles Studying Mysterious "Bent Horse"

Fran Gillespie

Seahorses! Everyone knows what they look like, but little is known about their way of life.

Mysterious Creatures

Seahorses are endearingly familiar images from classical art, in cartoon films, as children's bath toys and on shower curtains, and as jewellery. Their Greek scientific name, Hippocampus, means 'bent horse'. These bizarre-looking little fish, whose heads have the long, narrow muzzles and flared nostrils of pure-bred Arab horses and who swim upright, elegantly propelled by their fluttering dorsal fins, inhabit most of the world's oceans, including the Arabian Gulf. Yet much about their extraordinary lifestyle remains a mystery.

...much about their extraordinary lifestyle remains a mystery.

For a start, they are frustratingly difficult to spot. Seahorses inhabit sea grass beds at various depths, where they feed on small crustaceans, sucking them up through their tubular snouts. Microscopic particles of the crushed food escape through the gills in a nebulous cloud, making the creature look rather like a miniature smoke-breathing dragon. Although normally a slow-moving and slow-feeding fish, seahorses can put on a surprising burst of speed if their prey looks like escaping.

Seahorses can change colour, like chameleons, to blend in with their background. Canadian marine biologist Amanda Vincent, who knows more about seahorses than any other scientist worldwide, describes her embarrassment when she was working on seahorses in Florida in 1986 and at first failed to locate any, although she knew they must be present:

'It was really mortifying. To be underwater as a seahorse biologist and I couldn't find them! Eventually I got better at it...They're really well camouflaged: they grow long skin appendages so that they blend in better with the algae and let encrusting organisms settle on them.'

The secret, she says, is to look for the tail, wound firmly around a length of sea grass.

Seahorses in Qatar

Here in Qatar, four or possibly five of the world's species of seahorse, numbering approximately 35, are likely be present: Hippocampus fuscus, H. kelloggi, H. jayakari, H. lichtensteinni and H.kuda. Dr Mohsin A.

Al-Ansi, Director of the Environmental Studies Centre, a department of the University of Qatar, says that seahorses are easier to see by the light of a torch at night and that he spotted some around Halul Island some four years ago. But no work has yet taken place on recording and studying the species, and nothing is known about their distribution.

Reproduction

Not only is the appearance of seahorses bizarre, but their lifestyle is unique. The males become pregnant and give birth! Unlike mammals, among fish it is not uncommon for males rather than females to care for their young, but the seahorse takes this to extremes.

The male has a brood pouch at the front of his body, in which the female deposits her eggs. There they are fertilised by the male's sperm. This fertilisation within the body is highly unusual, as most fish simply release eggs and sperm and rely on the water to bring them together. The pouch lining becomes soft and secretes a liquid which nourishes the developing eggs, and also supplies oxygen through a capillary network.

The birth process may take as long as 24 hours, and the record ...is held by a male from the Caribbean which produced 1572 offspring.

Between two and five weeks later he expels the tiny baby seahorses from the pouch with a series of contractions. The birth process may take as long as 24 hours, and the record for the number of babies is held by a male from the Caribbean which produced 1572 offspring. But smaller species can produce as few as ten.

Mating

Seahorses are monogamous, remaining paired for life. The male tends to restrict himself to a territory of around a square metre, whereas the female will range more widely in search of food. Each morning during the male's pregnancy the female visits him and a greeting ritual takes place. They change colour from green or brown to a paler creamy shade, and link tails, swimming gracefully for a few moments of togetherness before the female sets off to forage.

Seahorses are monogamous, remaining paired for life.

This daily greeting not only reinforces the pair bond but also enables the female to check on the stage of her mate's pregnancy, so that she knows when to prepare a new clutch of eggs. Males are continuously pregnant throughout the breeding season.

During the mating ritual seahorses perform a kind of graceful underwater ballet which can go on for many hours, twirling with tails entwined, changing colours and moving their heads in unison.

This ritual is apparently more essential for the male than for the female, and if she allows herself to be distracted ... the male will peck sharply at her head!

One Caribbean species, H. reidi, even transforms into fluorescent neon colours during the mating dance. This ritual is apparently more essential for the male than for the female, and if she allows herself to be distracted by passing food, or even worse, shows interest in another male, the male will peck sharply at her head!

Life Expectancy

The life expectancy of seahorses in the wild is not known, but in captivity it averages two to four years. They reach sexual maturity at six months.

Once mated, they are slow to find another mate if their partner dies or disappears, and owners of seahorses in aquariums have reported that it is not infrequent for the surviving partner to pine away and die within a couple of days of losing its mate.

At Risk

Seahorses are on the World Conservation Union [IUCN]'s Red List of endangered species. The list includes species considered to be at risk, without enforcing any regulations. Such seahorse populations as have been studied are known to have declined – in some cases by as much as 50% over five years.

Because they inhabit sea grass beds, often in relatively shallow water, they are vulnerable to trawling and dredging. This is true of Qatar, where the seahorse colony which existed around Saffliyah Island north of Doha is feared to have fallen victim to the massive dredging activities associated with the construction of the Pearl Development.

...commercial uses are steadily taking their toll.

Seahorses have long been used in traditional Chinese medicines and many countries around the world are engaged in the trade. Scientists can only guess at the number caught each year, but one recent estimate is 20 million. In addition, wild seahorses are caught for the aquarium trade: In the USA the state of Florida alone landed 112,000 live animals in 1994. Dried seahorses have long supplied the tourist trade with key ring ornaments and the like. All these commercial uses are steadily taking their toll.

Project Seahorse

A worldwide organisation, Project Seahorse, has been working for more than ten years now on helping to control the trade in seahorses for medicine, which would prove impossible to ban altogether. Since May 2004 the trade has been controlled under CITES agreements.

Project Seahorse has been working for more than ten years now on helping to control the trade in seahorses for medicine

Project Seahorse has worked with a non-governmental organisation in the Philippines called the Haribon Foundation, to encourage poor fishermen, who are completely dependent on the seahorse trade, to keep any juvenile seahorses they may catch alive in sea cages for several months and allow them to breed before harvesting them. Small loans are made to the fishermen, which are repaid when the adult animals are sold for twice the price that a juvenile would have fetched.

Hippocampus fuscus, on algae beds near Khor al Adaid

In Hong Kong, Project Seahorse has been involved in research to examine the use of seahorses in medicine and the illnesses they are used to treat, to see whether there are medical alternatives using species which are not at risk and would limit the use of seahorses.

Because seahorses exist in most of the oceans of the world they are unlikely to become extinct, although individual populations, or even individual species, may die out. Here in Qatar more research needs to be done, to determine which species are present, the extent of their populations and whether they are at risk as Qatar rapidly expands and develops its coastline.

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