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The Differences Between the Sea Dragon & Seahorse

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Slowly swimming in upright positions, certain species of seahorse are common sights in coastal waters of North America. Their close relatives, the sea dragons, are endemic to Australian waters. While they may look similar, these two types of fish have a few key differences to help distinguish them.


Seahorses and sea dragons belong to the order Syngnathiformes and family Syngnathidae. As such, these two types of bony fishes share many similar characteristics. Seahorses belong to the genus Hippocampus, while their close relatives, the two species of sea dragons, belong to the genera Phycodurus and Phyllopteryx. The sea dragons are endemic to Australian waters, while seahorses roam mostly tropical and subtropical waters around different areas of the world.

Heads and Tails

Both seahorses and sea dragons share similar body shapes, although a few distinctions separate the two. Both have long, tubular snouts to help them suck up their prey, although sea dragons' snouts are a bit longer than those of their seahorse cousins. Differences in their tails also exist: sea dragons have longer tails that can't be curled like those of seahorses. Seahorses often use their tails to grab onto plants or structures to hold them in place.

Spines and Appendages

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Both seahorses and sea dragons have spines; one of the family characteristics is their bony plates and rings rather than internal skeletons. While the seahorses' bony plates create stiff spines along parts of the body, the sea dragons have leaflike appendages. The leafy sea dragon (Phycodurus eques) is much more elaborate, with loose, flowing appendages that look much like floating pieces of seaweed or other plant material. Weedy sea dragons (Phyllopteryx taeniolatus) are redder in color and have fewer appendages.


Both seahorses and sea dragons switch gender roles during reproduction, meaning the males carry out the pregnancy. The females of the species deposit the eggs in or on the male. This is where sea dragons and seahorses slightly differ. Male seahorses have a fully enclosed pouch; male sea dragons carry the eggs in a small, spongy patch on the underside of the tail.