U.S. Fish & Wildlife Services

Seahorses are fascinating sea creatures native to saltwater environments from the tropics to temperate zones. They are called “seahorses” because of their horse-like heads. Even their scientific name is based on the Greek word for horse (Hippocampus). The fins on the sides of their heads can beat up to 50 times a second, and their tails are prehensile (they can be used to hold onto or grasp objects) like a monkey’s. From a scientific perspective, seahorses are classified as fish.

Of the possible 50 species of seahorses known to science, at least six are native to the United States and Outlying Territories (American Samoa; Baker, Howland and Jarvis Islands; Guam; Johnston Atoll; Kingman Reef; Midway Islands; Navassa Island; Northern Mariana Islands; Palmyra Atoll; Puerto Rico; U.S. Virgin Islands; Wake Islands).
Seahorses are relatively immobile and they live in habitats such as mangrove forests and sea grass beds that provide food (usually brine shrimp) and shelter (including camouflage against predators). Seahorses spend a lot of time in one area by wrapping their tails around underwater plants or coral. In some species, male and female seahorses form monogamous breeding pairs – that is, they mate for life.

Perhaps one of the most fascinating facts about seahorses is that males give birth to the young! After the female deposits her eggs in the male’s brood pouch, he fertilizes the eggs and anchors himself to a solid surface to await the birth – sometimes for up to several weeks. Thus, the size of the wild population is unknown.

Several characteristics make seahorses naturally vulnerable to extinction. Although they are native to the waters off more than 130 countries, seahorses are patchy in distribution. Seahorses tend to have low birth rates, with lengthy parental care. In addition, the waters they live in are often exploited by people – usually for fishing or urban development – which degrades and destroys their habitats. Seahorses themselves are intentionally harvested by people for the curio and aquarium trade and for traditional medicines, both domestically and internationally.

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