Head to head
Seahorse vs Leafy Seadragon
Seahorses and seadragons are cousins in the same family, along with the pipefishes, and they share the group's oddest feature: it is the male that becomes pregnant. But they have gone in different directions. The seahorse is a gripper, curling its tail around seagrass and coral; the seadragon is a drifter, disguised as a piece of floating weed.
| Seahorse | Leafy Seadragon | |
|---|---|---|
| Family | Syngnathidae (seahorses, seadragons, pipefishes) | The same family |
| Who carries the young | The male, in a sealed belly pouch | The male, on a spongy patch under the tail (no pouch) |
| Tail | Prehensile; grips seagrass, coral, and other seahorses | Not prehensile; cannot grip |
| Camouflage | Changes colour to match the surroundings | Long leaf-like skin flaps mimic floating seaweed |
| Movement | Hovers upright; a poor swimmer that anchors with its tail | Drifts almost passively, moved by near-invisible fins |
| Size | About 1.5–35 cm depending on species | About 30–45 cm |
| Where it lives | Shallow coastal habitats worldwide | Only around southern and western Australia |
| Conservation | Many species threatened by trade and habitat loss | Near Threatened; protected in Australia |
Seahorse vs Seadragon: common questions
Are seahorses and seadragons the same thing?
They are close relatives in the same family, Syngnathidae, which also contains the pipefishes, but they are different animals. Seahorses are the upright, curl-tailed fish familiar from aquariums and logos; seadragons are larger, are found only around Australia, and are shaped and coloured to imitate drifting seaweed. Both have the tube-shaped snout, the bony-ringed body, and the male pregnancy that define the family.
Do male seadragons get pregnant like seahorses?
Yes, with a slight difference in the equipment. In seahorses the female transfers her eggs into a fully enclosed pouch on the male's belly, where he fertilises them, carries them, and eventually gives birth. In seadragons there is no pouch; the female attaches the eggs to a spongy, blood-rich patch of skin on the underside of the male's tail, and he carries them there in the open until they hatch. Either way, it is the father who is pregnant.
Why is a seadragon covered in leaves?
The leaf-shaped appendages are pure camouflage. A seadragon lives among kelp and seagrass and among the rafts of weed that break loose and drift, and by holding still with its frilly outline it becomes almost impossible to pick out from the surrounding vegetation. This hides it from predators and lets it drift close to the tiny shrimp it eats. The flaps are not fins and are not used for swimming, which the seadragon does with small, fast-beating transparent fins that are hard to see.