Seahorse
Hippocampus
Quick answer
The seahorse is a small marine fish with a horse-like head, an upright posture, and a curling, prehensile tail that grips seagrass and coral. It is one of the only animals in which the male becomes pregnant, carrying the eggs in a pouch until they hatch. Seahorses are weak swimmers that feed by ambush, and many of the roughly 46 species are threatened.
Seahorse facts at a glance
| Scientific name | Hippocampus (genus) |
|---|---|
| Diet | Carnivore (tiny crustaceans) |
| Habitat | Seagrass beds, reefs, and estuaries |
| Lifespan | 1–5 years depending on species |
| Length | 1.5–35 cm (0.6–14 in) |
| Top speed | Among the slowest fish |
| Conservation status | Vulnerable (many species) |
| Kingdom | Animalia |
|---|---|
| Phylum | Chordata |
| Class | Actinopterygii |
| Order | Syngnathiformes |
| Family | Syngnathidae |
| Genus | Hippocampus |
Where it lives
Shallow seagrass beds, reefs, and estuaries in tropical and temperate seas worldwide.
Pregnant fathers
Seahorses are famous for male pregnancy. The female deposits her eggs into a special brood pouch on the male's belly, where he fertilizes and carries them, supplying oxygen and nutrients, until he gives birth to dozens or even hundreds of tiny, fully formed young.
An unusual fish
Despite appearances, seahorses are true fish. They swim upright, propelled by a small, rapidly beating dorsal fin, and steer with tiny fins behind the eyes. With no scales, their bodies are protected by bony plates under the skin, and a prehensile tail lets them anchor to seagrass and coral against the current.
Ambush feeding
Seahorses have no stomach and no teeth, so they must eat almost constantly. They are ambush predators, anchoring in place and waiting for tiny crustaceans to drift near before sucking them up through their long, tubular snouts with a rapid snap of the head.
Conservation
Many seahorse species are threatened, with several listed as Vulnerable. They are harvested in huge numbers for traditional medicine, the curio trade, and aquariums, and they suffer from the loss of the seagrass and reef habitats they depend on. International trade in seahorses is now regulated.
Frequently asked questions about the Seahorse
Do male seahorses really give birth?
Yes. The female transfers her eggs into a pouch on the male's belly, where he fertilizes and carries them until they hatch, then releases the fully formed young, so the father truly gives birth.
Is a seahorse a fish?
Yes, seahorses are true fish. They breathe through gills, have a swim bladder, and swim using fins, even though their upright posture and horse-like head make them look very different from typical fish.
What do seahorses eat?
Seahorses are carnivores that feed on tiny crustaceans such as copepods and brine shrimp, sucking them up through their tube-shaped snouts. Having no stomach, they must eat almost constantly.
How do seahorses swim?
Seahorses are among the slowest fish. They swim upright using a fast-fluttering dorsal fin to move forward and tiny fins near the eyes to steer, and they grip seagrass with their tails to rest.
Why are seahorses endangered?
Many seahorse species are Vulnerable due to overharvesting for traditional medicine, souvenirs, and the aquarium trade, along with the loss of the seagrass beds and coral reefs they depend on.
