There are three main groups of fish. The sea horse, breathing through gills, belongs in the family Syngnathidae along with Pipefish. There are approximately 35 sea horse species around the world residing in coastal regions among sea grasses and corals. These fish propel themselves through the water with a dorsal fin using pectoral fins to steer. However, these fins and gills are seemingly the only characteristics they share with other fish.
The seahorse swims upright and has a long tube like snout held at a right angle to its body. These features make it appear to be a small underwater horse. In addition, rather than having a tail fin the sea horse has instead a long, prehensile tail.
The Seahorse Body
The seahorses unusual and agile tail allows it to hold onto various seaweed and underwater plants where it hides looking very much like the plants it uses for cover.
Not only does its upright position help it to blend in, but the seahorse is able to camouflage itself with color appearing in many colors from white, to ebony, greens, and bright oranges and reds. These color changes occur when the sea horse expands or contracts tiny pigment cells, called chromatophores, in its skin.
Rather than being covered with scales the seahorse has bony plates. These plates help to protect it and serve as ribs for the seahorse which has no rib bones. On these plates, some species of seahorses develop small branch or twig like protrusions. These protrusions are called dermal cirri and are part of the camouflage of some seahorses, helping them to look more like the plants in which they live
Through the long tube like snout seahorses are constantly feeding. They use the tube to suck in plankton, brine shrimp, tiny crustaceans, and baby fish. The seahorse eats almost continually consuming only live food.
Most seahorses select a mate for life. Even after losing a partner seahorses will not select a new mate for a prolonged period of time. Also the new pair generally produces less offspring than the original mates.
During mating the female seahorse lays up to 200 eggs in a front pouch on the male seahorse. She does so by inserting her egg tube, or ovipositor, into the pouch and dropping the eggs. Inside the male’s pouch the eggs are fertilized and a system of support veins grow around the eggs to provide nutrition. Two to six weeks later the eggs are fully developed and the baby seahorses are ready to be born.
During the birthing process the male assists the young in leaving his pouch by muscle contractions which squeeze the pouch pushing the newly born seahorses into the ocean. Most seahorses tend to deliver their young in groups although some are born individually. The whole birth process can last up to 2 days, leaving the male seemingly weak with fatigue.
Dangers for the Seahorse
In the water seahorse have some natural predators. These creatures include crabs, rays, skates, and tuna. In addition storms can tear them from their holding place to be cast ashore or die of exhaustion from swimming with no place for their tail to hold.
Out of the water man is also a threat to the seahorse’s survival. Not only does man threaten the seahorse habitat with pollution and trawling, but humans hunt this creature for a variety of reasons.
Seahorses are used in many traditional cultures including Chinese medicine and cooking. They are also hunted as souvenirs, appearing in glass domes, on key chains, or in a variety of other crafts or devices. And hobbyists with aquariums often purchase seahorses, only to discover that they are difficult to keep alive particularly since they require a constant live food source and are prone to disease.
Facts about Seahorses
- The dwarf seahorse species grows to be only about ¼ inch in length.
- Seahorses have no teeth and no stomachs.
- The common seahorse of the Atlantic coast of North America is one of the largest species growing more than 5 inches (13 cm) in length. Another large species, the Pacific Seahorse can grow to a length of more than 12 inches.
- The life span of a seahorse in the wild is not known, but it is thought to be about 1-4 years.
- The genus name of seahorses, Hippocampus, comes from 2 Greek words - hippos which means horse and campus which means monster.
- Although most seahorses select a partner for life, some species of female sea horses who have more eggs than the male’s pouch will can carry, will search for a second male to carry the rest of her eggs. Likewise a male who has room left in his pouch for more eggs will mate with another female in order to fill his pouch.
- The eyes of a seahorse work independently of each other.
- Most young seahorses do not fully mature until they are a year old making their reproductive availability much slower than other fish.
- Seahorses will allow encrusting animals to settle and dwell on them. These serve as further camouflage.
- Baby seahorses, after being born, must rise to the surface to gulp air. This air fills their swim bladder giving them their buoyancy.
- The sea dragon is a type of seahorse which grows ornate leafy flaps and weed-like extensions. Unfortunately it is a weak swimmer and has no prehensile tail, so it is often cast ashore to die.
- The external, bony covering on a seahorse is called integument
Books for Children
- Sea Horse (Living Things) by Rebecca Stefoff - This book has clear photographs and simple but informative text. The description of this creature and its life cycle is interesting. It also includes sections about octopuses and sea stars. Appropriate for ages 6-10. (amazon.com has it)
- Fish: Eyewitness Book by Steve Parker - Describing a variety of different fish, through colorful photographs and a wealth of facts about their habits, lifecycles, and anatomy this book is fascinating. Included is a section about seahorses and their relatives the pipefish. Appropriate for ages 7-12. (amazon.com has it)
- One Lonely Sea Horse by Saxton Freymann and Joost Elffers - This is a simple counting book about a seahorse named Bea and the friends she makes. While the bright pictures and simple reassuring text make this a wonderful book for the very young, the fact that the pictures are made of real fruits and vegetables will have even adults amazed. Nice for ages 1 and older. (amazon.com has it)
- Hello, Fish! Visiting the Coral Reef by Sylvia A. Earle - A book of poetic prose about the coral reef and its inhabitants. While there is only one short description about the seahorse, this book will give young children an appreciation for all the creatures which live in and around the coral reef. The wonderful photography is engrossing each time you look. Nice for ages 3-10. (amazon.com has it)
- Kingdom of the Seahorse by NOVA online - This site includes basic facts about seahorses as well as an interview with a seahorse biologist. The "seahorse roundup" has some nice photographs of seahorses.