Seahorses are so instantly
recognisable that they almost need no introduction. Creatures of myth and
storybook, it comes as a surprise to many people that they are in fact fish,
complete with gills and fins. Unlike most fish, however, they have a tube-like
snout, bony external armour instead of scales, and a grasping tail to hold onto
seagrass, corals or other holdfasts. They are also unusual because it is the
male that broods the young, and most species studied to date form strong
pair-bonds that are maintained by daily greetings.
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| Dwarf seahorse (Hippocampus zosterae). |
Highly sought after for
traditional Chinese and other Asian medicines, as well as for curiosities or
aquarium fish, it appears that the trade is not sustainable. Seahorses are
caught accidentally in trawl nets by the millions, and given the fact that they
tend to live at low densities and have complex social structure, this is
decimating their populations. As a result of these threats, they are the focus
of much conservation concern.
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| The seahorse trade appears not to be sustainable. |
The oldest seahorse fossils were
found in 12.5 million-year-old silt-stone deposits in Slovenia, but genetic
data suggest that seahorses evolved from pipefish-like ancestors approximately
28 million years ago. Today they are found in shallow tropical, subtropical and
many temperate seas throughout the world. A few are found in estuaries, but
there are no truly freshwater seahorses.
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| Réunion seahorse (Hippocampus borboniensis). |
There are approximately forty species
in the genus Hippocampus (meaning ‘horse sea-monster’)
living in a variety of habitats, including coral reefs, seagrass beds,
mangroves and soft-bottom areas. They range in size from the pygmy seahorses
(such as Hippocampus satomiae,
~ 1 cm in height) to the
giant Pacific seahorse (H. ingens, > 30 cm in height).
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| Satomi's pygmy seahorse (hippocampus satomiae). |
They are
relatively conservative in their body form, although they vary in terms of
their body ornamentation, spines, coronet shape and size, fin rays and body and
tail rings. As ambush predators, they rely on stealth and camouflage to avoid
detection by their prey, aided by their ability to change colour to match their
surroundings. They eat small crustaceans (such as tiny shrimp, or crab larvae),
which they efficiently vacuum up with their snout using some of the most rapid
suction action known in the animal kingdom.
 |
| Ribboned pipefish (Haliichthys taeniophorus). |
Drawing on much of the latest
research, Seahorses is an in depth, but accessible
introduction to these fascinating creatures. It provides background details
about their ecology, behaviour and evolution, as well as their connection with
humans in terms of culture, trade, and conservation action. The second half of
the book provides a species by species account of all the seahorses, as well as
a selection of their relatives within the family Syngnathidae, including a
number of pipefishes, pipehorses, and seadragons. The book hopes to inspire and
educate readers, as well as to raise awareness of the fragility of the marine
realm. Can the charisma of theses unusual creatures help motivate conservation
action for seahorses and their imperiled marine habitats?
Sara Lourie has
been involved with Project Seahorse, an international marine conservation
organisation, since it was founded by Amanda Vincent and Heather Koldewey in
1996. She published the first seahorse identification guide in 1999, described
several new species of pygmy seahorses, and received her PhD from McGill University
in 2004, with a thesis on the genetic connections among populations of
seahorses in Southeast Asia. She has travelled extensively and continues to work on marine conservation
projects, particularly in Indonesia.
Seahorses: A Lifesize Guide to Every
Species by Sara Lourie is published by Ivy Press.
