Seahorses are familiar and loved as the peculiar upright fish which graces bathroom tiles, beach towels, cartoon movies, children’s books, and even jewelry. That’s when we’re not grinding them into powder for traditional medicines.
Pregnant seahorse males, bellies big with embryos, rest in seagrass.
NGS photo by Paul Zahl
Although some people own seahorses in private aquariums, the great bulk of humanity has never seen a live one in the wild. For the most part they’re tiny, solitary, and adept at hiding in coral reefs or seagrass. Yet they live in many parts of the world, and can be found even in fairly close proximity to popular beaches.
Marine biologist Helen Scales, a regular contributor to National Geographic News, has written a compelling book about seahorses that makes the case not only for these odd fish but also for the entire ocean.
“Seahorses may be incongruous and small, they may hide in quiet corners of the coast away from all but the keenest of eyes, but they can play an important role in encouraging us to protect parts of their vast ocean home,” Scales writes in “Poseidon’s Steed: The Story of Seahorses, from Myth to Reality” (Gotham Books, August 2009, U.S.$24.00).
“Increasingly, seahorses are being used as catalysts for conservation initiatives; they are being held aloft as poster species to help muster support for protecting the oceans.
“They are touchstones to remind people of the vulnerable, beautiful creatures that live there, giving us a reason to care.”
Scales describes in absorbing detail the prehensile tail seahorses use to tie themselves to a perch, a pair of chameleon eyes capable of moving independently of each other, a coat that can change colors to blend invisibly into the background, and a long tube of a snout to suck in passing plankton like a powerful vacuum cleaner.
The seahorse is the only fish with a neck and the only species on Earth in which the male gives birth.
A dwarf seahorse mimics plumes of hydroids on turtle grass.
NGS photo by Robert Sisson
Seahorses, one might imagine, are masterpieces of evolution, reaching their unique morphology and niche in the web of life through many twists and turns over millions of years.
The origins, distribution, and life history of the seahorse is fascinating in and of itself, and Scales does a nice job of detailing all this.
But she really comes into her own when she delves into the mythology based on the seahorse (the title of the book is a reference to ancient art of the Greek god Poseidon’s chariot being pulled by seahorses) and to the thousand-year tradition of using seahorses in Chinese medicine as cures for flagging libido and a variety of other ailments.
It’s the booming trade in traditional medicine that is the biggest threat to seahorses. Some 25 million seahorses are fished from the oceans every year, according to Scales.
Much of the extraction is bycatch in the shrimp fisheries, which use trawl nets to scrape all living things from the seafloor. Seahorses are picked out of the writhing heaps of shrimp, sponges, and other marine animals gathered by the nets, then set aside for sale to the traditional healing trade. It can be a lucrative sideline for fishers.
Five pygmy sea horses range in color from dull brown to golden yellow.
NGS photo of seahorses by Paul Zahl
Scales provides a nuanced and thoughtful analysis of traditional medicine in general, branching her analysis into the pros and cons of farming endangered species (yes, there are seahorse farms, and 18 seahorse species now live in aquariums) and she gives a fair hearing to those who argue that a billion users of Chinese traditional medicine cannot all be wrong about its efficacy.
But it’s clear that irresponsible fishing practices, and an insatiable appetite for rare wild species as traditional medicine, are the biggest threats to seahorses and countless other marine animals.
Sea horses, one yellow and one green, suck plankton via their snouts.
NGS photo by Paul Zahl
Other threats to seahorses include habitat destruction because of coastal development and runoff.
A warming world could raise ocean temperatures, and also raise sea levels that could make what are now shallow seas deeper and darker. The changes could come too rapidly for many species to adapt, especially animals like seahorses which may not be able to relocate to cooler latitudes fast enough.
A pygmy sea horse pops out of its father’s pouch tail first at birth.
NGS photo of seahorse by Paul Zahl
One of the rarest seahorses is the Cape seahorse, also known as the Knysna seahorse. They occur in only a small part of the coast of South Africa and are vulnerable to a major natural disaster. Watch this National Geographic video about them:
There is some good news for seahorses.
Scales reports on Project Seahorse in the Philippines as an example of artisinal fishers taking the initiative to zone off and protect ocean sanctuaries where species, including seahorses, can recover and restock adjacent fishing areas.
Cleaning up rivers has also had an important impact on seahorses. An example of this is the Thames River in England, which has recovered to the point where seahorses are being seen again as far upriver as London for the first time in many years. (Read the about this in the National Geographic News report Rare Seahorses Found in River Thames.)
An Australian male sea horse grasps a stalk of algae with its tail.
NGS photo of seahorse by Paul Zahl
One of the most enjoyable features of “Poseidon’s Steed” are the many digressions. There can be few, if any, aspects of seahorses in mythology, history, or the popular culture that Scales does not investigate.
Thorny cirri, skin branchings, sprout from a pygmy sea horse’s head.
NGS photo by Paul Zahl
Everything Scales writes about is well researched and explained, and the additional details in the book’s comprehensive footnotes speak not only to her academic diligence but also her journalistic professionalism to provide context and explanation.
The bibliography runs for an impressive number of pages. I’ve never read a book devoted entirely to seahorses before, and I may never read another one. But I am very glad I read this one. It feels like a lucid distillation of a lot of research and careful thought.
My one disappointment with the book is that it lacks great color photography. I know from our news coverage that seahorses can make gorgeous photos. For an example of this, look at the images in SEA LIFE PHOTOS: Five New Pygmy Seahorse Species Found (captions written by Helen Scales).
I was expecting a book that dealt with many aspects of a delightful and enigmatic fish. I found all that and so much more.
Scales has provided much useful information and context for the wider issues of the long relationship we have had–and continue to have–with our oceans and the animals that live in them.
“Poseidon’s Steed” takes a look at the oceans from the point of view of the seahorse, and in doing so gives us a profound appreciation of what’s a stake for everything that lives in or depends on the sea, ourselves included.
You might also like these National Geographic News stories:
SEA LIFE PHOTOS: Five New Pygmy Seahorse Species Found
The Walea pygmy seahorse is one of five species named in a flurry of recent seahorse discoveries from coral reefs in the Red Sea and Indonesia. All five are less than an inch tall (2.5 centimeters) and are among the tiniest known vertebrates.
PHOTOS: Oldest Seahorses Found; Help Solve Mystery
The oldest seahorse fossils discovered to date have been uncovered in Slovenia, including a two-inch-long (five-centimeter-long) adult female Hippocampus sarmaticus fossil.
How Seahorses Evolved to Swim “Standing Up”
Seahorses are master mimics that use their cryptic colors and upright posture to blend in with plants. When and why the animals developed these unusual characteristics has been a mystery–until now, scientists say.
Seahorse in a Sea Fan (Best Photo Contest)
This exquisitely camouflaged pygmy seahorse on a sea fan in the Malaysian section of the South Pacific island of Borneo won first place prize in an amateur underwater-photography contest.
National Geographic News stories by Helen Scales: