Review: Poseidon's Steed, by Helen Scales

If asked what a seahorse is, a person able to answer at all would most likely reply: "an animal," or perhaps "a fish." Indeed, seahorses are extraordinarily interesting fishes, but they are also many other things, including mythological creatures, medicinal healers and catalysts of the change desperately needed for our oceans. In her book Poseidon's Steed: The Story of Seahorses from Mythto Reality, British marine biologist Helen Scales introduces us to all sides of the seahorse, from "myth to reality."

Scales's treatment of seahorses is truly interdisciplinary, covering a wide range of subjects. Readers will walk away with a greater understanding of the fish, but also of archeology, taxonomy, traditional medicine, the history of aquariums and international trade conventions (among other matters). Her words will inspire visits to the world's museums as much as diving in its oceans. Each chapter is a perfect blend of past and present, fact and whimsy.

Indeed, Scales writes much like her description of filmmaker Jean Painlevé, in her "ability to blend art with science. [Her]work is rich with stylish imagery … [but does]not shy away from scientific detail."

With a horse's head, kangaroo's body, monkey's tail and the swiveling eyes of a chameleon, it is easy to see how seahorses have captured imaginations across the millennia. Australian aborigines painted Rainbow Serpents, bearing striking similarities to seahorses, on cave walls. The Lydians, Minoans and Picts portrayed them in various fantastic forms in stone carvings, and on coins and jewellery. And who can forget the image of the strong "hippocampus" (half-horse, half-fish) pulling the chariots of Poseidon and Neptune, the gods of the sea.

While atypical in their form, seahorses are like other marine fishes, using gills to breathe and a swim bladder to control buoyancy. The 37 species described to date range in size from two centimetres to more than 30. They inhabit coral reefs, sea-grass beds and mangrove forests found along all but the coldest of ocean coasts. Many species are monogamous, some for a breeding season, and some for life.

But seahorses are perhaps most famous because they are the only animals in which the male gets pregnant. A male nurtures his developing young in a womb-like pouch and, when they're fully developed, he "convulses in intensifying contractions" to set them free.

Unfortunately, seahorses face an uncertain future. They are in high demand for traditional medicines, especially traditional Chinese medicine (TCM). Dried seahorses are used to cure a variety of ailments from respiratory diseases to waning libidos. They are also in demand for display in aquariums, and to add new brood stock to seahorse farms.

Scales's discussion of the uses for seahorse is well balanced. While making a case for the efficacy of TCM, suggesting that a billion users cannot all be wrong, she also urges "practitioners to seek out alternative traditional ingredients that have similar effects" to "help stem the growing demand for seahorses and other endangered species."

After reviewing the potential negative impacts seahorse farming can have on wild populations, she reminds us that aquariums "offer us a chance to reconnect with nature, lending meaning to the inflating inventory of ecological disasters going on in the wider world beyond the concrete pavements of the cities and towns where so many of us live."

Seahorses enter trade from two sources. The majority are indiscriminately plucked from the ocean floor by shrimp trawlers, to be discovered by fishers when sorting their catch for shrimp. The only way to reduce this type of exploitation is to ban trawling from seahorse habitats, as they would still be captured even if there were no reason to keep them.

Other seahorses are fished by hand. These small-scale fisheries have more potential for sustainability, as they can be regulated with closed areas, but also size restrictions to ensure seahorses breed before being removed from their population. In addition to overexploitation, seahorses are threatened by damage and destruction of their habitats from "marinas and shrimp farms … silt, pesticides, and fertilizers … too much fishing and pollution … spiralling development … sewage" and too many people.

Seahorses are also at risk from global warming. Scales explains the threats facing the ocean life in terms that everyone can understand, and thus, one hopes, feel some responsibility for.

As someone who works to save seahorses, I am often asked why seahorses matter, and I must thank Scales for answering this question so completely. The threats facing seahorses are the same as those facing the majority of creatures that inhabit oceans; thus, saving seahorses really does mean saving the seas. They have been the catalyst of local initiatives throughout the world to protect coastal habitats, as well as opening the doors of international conventions that were previously closed to marine fishes. They make people care about the oceans, even those who have never visited the shores of one.

And perhaps most of all, Scales reminds us of the intrinsic value of nature - that its sheer existence matters. Our world is indeed "absolutely a better place just knowing there are seahorses swimming through the oceans."

Sarah Foster is a scientist with Project Seahorse, an interdisciplinary and international organization committed to conservation and sustainable use of the world's coastal marine ecosystems. She has co-written scientific papers, policy documents and an identification guide on seahorses.