Get 10 Seahorse Facts

Author and marine biologist Helen Scales, Ph.D., said of seahorses in her book Poseidon's Steed: "They remind us that we rely on the seas not only to fill our dinner plates but also to feed our imaginations." Here you can learn more about seahorses - where they live, what they eat and how they reproduce.

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Seahorses are fish.

Sea horses
Georgette Douwma/The Image Bank/Getty Images

After much debate over the years, scientists finally decided that seahorses are fish. They breathe using gills, have a swim bladder to control their buoyancy, and are classified in the Class Actinopterygii, the bony fish, which also includes larger fish such as cod and tuna. Seahorses have interlocking plates on the outside of their body, and this covers a spine made of bone. While they have no tail fins, they have 4 other fins - one at the base of the tail, one under the belly and one behind each cheek.

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Seahorses are bad swimmers.

Craig Nagy / Flickr / CC BY-SA 2.0

Although they are fish, seahorses are not great swimmers. In fact, they Seahorses prefer to rest in one area, sometimes holding on to the same coral or seaweed for days. They beat their fins very quickly, up to 50 times a second, but they do not move quickly.  They are very manueverable, however - and able to move up, down, forward or backward.

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Seahorses live around the world.

Longsnout Seahorse
Longsnout Seahorse (Hippocampus reidi). Cliff / Flickr / CC BY 2.0

Seahorses are found in temperate and tropical waters throughout the world. Favorite seahorse habitats are coral reefs, seagrasses, and mangrove forests. Seahorses use their prehensile tail to hang out on objects such as seaweed and branching corals. Despite their tendency to live in fairly shallow waters, seahorses are difficult to see in the wild - they are very still and blend in very well with their surroundings.

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There are 53 species of seahorses.

Pacific Seahorse
Pacific Seahorse. James R.D. Scott / Getty Images

According to the World Register of Marine Species, there are 53 species of seahorses. They range in size from under 1 inch, to 14 inches long. They are categorized in the Family Syngnathidae, which includes pipefish and seadragons.

Yellow pygmy seahorse
Yellow pygmy seahorse (Hippocampus bargibanti). Wolfgang Poelzer/WaterFrame/Getty Images

Seahorses feed on plankton and small crustaceans. They do not have a stomach, so food passes through their bodies very quickly, and they need to eat nearly constantly. More »

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Seahorses may have strong pair bonds... or they may not.

felicito rustique / Flickr / CC BY 2.0

Many seahorses are monogamous, at least during a single breeding season.  A myth perpetuates that seahorses mate for life, but this doesn't seem to be true. Unlike many other fish species, though, seahorses have a complex courtship ritual and may form a bond that lasts during the entire breeding season.  The courtship involving a "dance" where they entwine their tails, and may change colors. So, although it may not be a long-lasting match, it can still look pretty enchanting.

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Male seahorses give birth.

Pregnant Seahorse
Kelly McCarthy / Flickr / CC BY-SA 2.0

Unlike any other species, the males become pregnant.  Females insert her eggs through an oviduct into the male's brood pouch. The male wiggles to get the eggs into position. Once all the eggs are inserted, the male goes to a nearby coral or seaweed and grabs on with his tail to wait out gestation, which may last several weeks.  When it's time to give birth, he'll contort his body in contractions, until the young are born, sometimes over a period of minutes or hours.  Baby seahorses look just like miniature versions of their parents.

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Seahorses are experts at camouflage.

Pygmy Seahorse
Pygmy Seahorse (Hippocampus bargibanti). Steve Childs / Flickr / CC BY 2.0

Some seahorses, like the common pygmy seahorse, have a shape, size and color that allows them to blend in perfectly with their coral habitat. Others, such as the thorny seahorse, change color to blend in with their surroundings.

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Humans use seahorses in many ways.

Seahorses in a jar
Dead seahorses for sale in Chinatown, Chicago. Sharat Ganapati / Flickr / CC BY 2.0

In her book Poseidon's Steed, Dr. Helen Scales discusses our relationship with seahorses. They have been used in art for centuries, and are still used in Asian traditional medicine. They are also kept in aquariums, although more aquarists are getting their seahorses from "seahorse ranches" now rather than from the wild.

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Seahorses are vulnerable to extinction.

Dried Seahorses, Malaysia / Stuart Dee / The Image Bank / Getty Images
Stuart Dee / The Image Bank / Getty Images

Seahorses are threatened by harvesting (for use in aquariums or Asian medicine), habitat destruction, and pollution. Because they are hard to find in the wild, population sizes may not be well-known for many species.  Some ways you can help seahorses are not purchasing souvenir seahorses, not using seahorses in your aquarium, support seahorse conservation programs, and avoid polluting water by not using chemicals on your lawn and by using eco-friendly household cleaners.