A s a marine biologist, one of the weirder creatures I’ve encountered is Velella velella, a type of jelly that looks like a blue sailboat grafted to

Oceans on Nautilus: Hidden in Plain Sight

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2021-07-19 10:00:03

A s a marine biologist, one of the weirder creatures I’ve encountered is Velella velella, a type of jelly that looks like a blue sailboat grafted to a feather boa. We don’t know much about Velella: where they live and what they eat; where they go when they’re young and how big they get when they’re old. But we’ve got some ideas, because every year these living sailboats turn beaches around the world bright blue.

Velella are the black sheep of the jelly family. For one, they’re waterproof. A sail made of flexible material called chitin extends from their oval-shaped bodies, twirling them with the wind. The sail is given heft by a plastic-like skeleton and is anchored to a chamber that looks something like the hull of a ship and is filled with gas, which is how they stay afloat. Below deck is a ring of tentacles surrounding a central mouth. When the wind carries Velella near shore, they prey on small fish, eggs, and rice-shaped shrimp-like animals called copepods.

When it’s time to reproduce, Velella bud tiny jellyfish from their bodies. These baby jellies, each the size of a sesame seed, sink into deeper water where they mate and give birth to new floating Velella.