Seahorses: Enigmas of the Sea
Beneath the tranquil surface of the sea lies an aquatic world that delights the human eye. To the spectator, the collective vision of marine life displays the full spectrum of the colour wheel. The wonders of the ocean have intrigued observers from the earliest of times and have been the basis of many scientific studies. Interwoven between leafy seagrasses, the twisted roots of mangroves and vivacious corals, lives the seahorse, a small marine animal that is renowned for its vibrant colour and remarkable appearance.
Seahorses belong to the genus Hippocampus, a name that comes from the Greek word ‘Hippokampos’ – hippos meaning horse and kampos meaning sea monster. When considering the appearance of the seahorses, their Greek name is very fitting: having a horse shaped head, a body that is encased with hard bony armour, a strong prehensile tail that can grip tightly around objects, and eyes that can move independently of each other – monster sounding indeed! Though their description sounds ferocious, these whimsical creatures rely on their ability to quickly change colour to camouflage themselves with their surroundings, thus protecting them from their predators. With their ability to change colours, it is no wonder that they have earned the alias of ‘the chameleons of the sea’.
Oceanic creatures have long inspired many colourful tales of mystery and intrigue. Fanciful stories of sunken treasures that were guarded by mythical sea creatures and tales of giant seahorses that swam alongside beautiful mermaids have been passed down through the centuries via the aide of well-preserved manuscripts and artworks. Their appearance rendered in the mind’s eye a vision of a sublime creature that stood apart from other marine animals. Throughout history, the seahorse has managed to captivate the hearts and minds of many accomplished artists and poets.
In Greek mythology, hippocampi (seahorses) pulled the chariot of Poseidon, and the Nereides – who were the sea-nymph sisters of the sea – rode upon their backs. Legends suggest that the Nereides and their seahorses rendered assistance to sailors in need. As a result of these ancient legends, the seahorse was adopted as a symbol of safe sea travel. Citizens from seaport towns often portrayed the image of the seahorse on coins, heraldry and signs. Naval ships – such as the HMS Seahorse, a frigate that was built in 1748, was also named after this aquatic animal.
While legends of the seahorse spurred the imagination of poets, artists depicted this enchanting creature in drawings and mosaics that date back to the Roman era. Seahorses were often rendered as large sea-monsters who were half-horse and half-fish. They were also believed to possess mystical and therapeutic powers. A beautifully preserved Roman public bath can be found in the English city of Bath. The public bath, filled via the waters of a natural mineral spring, was known for its healing qualities. Due to the healing properties of the water, it was only fitting that the mosaic tiles that decorated the surroundings of the public bath depicted the image of the seahorse.
Preserved sites of historical significance highlight the importance of the seahorse to past civilizations and it is interesting to note that belief in their mystical and therapeutic powers did not fade out of all existence with the passing of time. In the midst of today’s modern existence and technological advancements, some cultures still believe in the healing properties of seahorses. As a consequence of this belief, the demand for traditional medicines has placed the seahorse population at risk. Traditional Chinese medicine sees an estimated yearly catch of over 20 million seahorses. Seahorses have been used for centuries and are considered to be an excellent treatment for a variety of ailments such as impotence, infertility, asthma and throat infections.
Human activity has had a devastating effect on the number of seahorses that reside in the wild. Pollution, overfishing and the destruction of seagrass beds, mangrove swamps and coral reefs threaten their delicate ecosystem. Seahorses are sparsely distributed and have a low mobility rate. It has been observed that most adult seahorses maintain small home ranges – as little as two square metres, therefore it is very difficult for these marine animals to repopulate should morbidity occur. Unfortunately, it is a sad fact that many juvenile seahorses are fished before they have a chance to reproduce. Currently, the future of seahorses that live in the wild lies in the midst of ambiguity. While crabs, rays and tuna are natural predators, nothing threatens the seahorse population more than the destructive influence of mankind.
Maintaining healthy waterways is essential for the preservation of these delightful marine animals. Habitat degradation via pollution and shoreline developments contributes to the breakdown of essential food chains. Though seahorses are slow feeders, they can consume up to 3000 tiny shrimp per day, which they swallow whole by sucking them in through their snout. Clean and undisturbed waterways are essential for the preservation of seahorses and the small crustaceans that they consume.
There are numerous species of seahorses that can be found in Australian waters, each of which differs slightly from each other in both colour and appearance. According to the Zoological Catalogue of Australia, Volume 35 (2006), there are currently twenty-four recognised species of seahorses in Australian waters. The Whites seahorse (Hippocampus whitei) – which lives in Sydney Harbour – tends to have brown or yellow colourings, depending of its surroundings; while the Zebra seahorse (Hippocampus zebra) – which can be found off the coast of far North Queensland – has distinctive black and white stripes over its head and body.
Moreton Bay, in Queensland, boasts a number of seahorse species, including the Low-crown seahorse (Hippocampus dahlia), and the High-crown seahorse (Hippocampus procerus). Dr. Sue Pillans, during her PhD research in Moreton Bay, was fortunate enough to catch a number of High-crown seahorses. She states that this seahorse was caught in the seagrass beds located within inshore coastal environments such as, but not limited to, Pumicestone Passage and Southern Moreton Bay. Jeff Johnson, from the Queensland Museum also says that the Queensland seahorse (Hippocampus queenslandicus) is also known to exist in the offshore waters of South-East Queensland. He states, “there is some long term anecdotal evidence that numbers of seahorses in the area have declined, but the extent of any decline has not been quantified”. Major threats to seahorses may stem from a combination of factors, such as the degradation and removal of seagrass beds, and over-harvesting due to the commercial collection of these species for use in traditional Chinese medicine.
In order to survive in the wild, seahorses have developed some rather ingenious methods of outwitting their predators. They have mastered the art of camouflage in that they have developed the ability to change their colour to match with that of their surrounding environment, such as corals and seagrasses. Transitory colour changes can also take place while preforming courtship rituals and morning greetings. Colour change in seahorses is achieved through the contraction or expansion of pigment cells known as chromatophores, which are located in the dermis or epidermis of the seahorse.
To this date, the number of seahorses in Australian waters remains unknown due to the fact that there are only a few small areas around Australia where monitoring sites have been established; therefore, recorded data is limited. At a monitored site in Sydney, a study was conducted by Dr. Keith Martin-Smith, from the University of Tasmania. The recorded data indicated that the seahorse population in Sydney Harbour remained reasonably steady over the period of 2001-2003/4; however these numbers declined in one area after the habitat was disturbed by the replacement of a swimming enclosure net.
There would be few who could contest the beauty and splendour of the seahorse. Only a handful of other marine animals have been characterised in as many myths and legends; however – and like so many other marine animals – they remain to this day the target of exploitation. The ocean is an environment that is shared between the marine life and the commercial and recreational activities of mankind; and if seahorses are to have a continued existence, it is imperative that their habitats remain intact.
The good news is that some positive steps have already been taken. Currently, seahorses are listed under the Convention on International Trade in Endangered Species (CITES), which restricts the use of seahorses in the manufacturing for trade purposes, such as traditional medicines. Australia is one of more than 150 countries that have joined CITES. While this is a positive move, additional protective measures must be implemented. Exploitation must remain at a sustainable level; pollution levels must be reduced and monitored; and deliberate and accidental by-catch fishing must be avoided as much as possible. While aquaculture may help to sustain the seahorse population, these measures are no substitute for an in situ marine environment.
In order to protect these beautiful creatures for future generations, additional research sites are needed, as is the implementation of a public awareness campaign that highlights the fragility and beauty of the marine ecosystem. Maintaining healthy waterways and avoiding habitat disturbance will go a long way towards the preservation of the seahorse and their aquatic world of colour.
Department of the Environment and Water Resources. (1999) Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) 8 August 2007 < http://www.environment.gov.au/biodiversity/trade-use/cites/index.html>
Garrick-Maidment, Neil., Seahorses: Conservation and Care. London: T.F.H. Kingdom Books, 1997.
Johnson, J. “Re: WPSQ Seahorse Article”. E-mail to Dianne G. Hausler. 14 August 2007.
Kuiter, Rudie H. Seahorses, Pipefishes and their Relatives: A Comprehensive Guide to Syngnathiformes. Chorleywood: TMC Publishing, 2000.
Martin-Smith, K. “Re: WPSQ Seahorse Article”. E-mail to Dianne G. Hausler. 10 August 2007.
Pillans, S. The Effectiveness of No-take Marine Reserves in Moreton Bay, Subtropical Australia. PhD Thesis, University of Queensland, Brisbane, 2006.