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Jellyfish

jellyfish

Jellyfish
Photo by Dylan R · CC0

About

Jellyfish are soft-bodied drifters with a bell-shaped body and trailing tentacles. In this app the group includes the Moon Jellyfish, the Lion's Mane Jellyfish, and the Portuguese Man o' War.

How to tell it apart

The soft, see-through bell with trailing tentacles and no fins or shell sets jellyfish apart from every other reef animal. Members are told apart by bell shape, colour, and how long and how many tentacles trail behind.

Appearance

A jellyfish has a soft, see-through, umbrella-shaped bell made mostly of water. Tentacles hang from the edge of the bell, and arms hang down from the mouth underneath. Size and tentacle length vary a lot between species.

Habitat

Jellyfish drift in open water and along coasts in oceans worldwide. They can gather in large groups, called blooms, where currents, warm water, or high nutrients let them thrive.

Behaviour

Jellyfish mostly drift with the current, using slow pulses of the bell to move. They hunt passively, trailing their tentacles like drift lines or sinking through the water to meet prey.

Diet

Most jellyfish eat plankton, small crustaceans, fish eggs, and small fish, which they catch and stun with stinging tentacles. A few species also get some nutrition from algae living in their tissue.

Breeding

Jellyfish usually release eggs and sperm into the water, where they mix and grow into larvae. These larvae settle and grow into a stage that later buds off into new young jellyfish.

Did you know?

A group of jellyfish is called a 'smack'.

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Describe what you saw and we name it, then keep every species you find in your Oceandex.

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