Invertebrates

Sea Jellies

Other Common Name(s)

Jellyfish

Body Weight

Depending on species, some may exceed 200 kg

Body Length

The largest species, Lion’s Mane Jellyfish (Cyanea capillata), can have tentacles reaching about 36m. The tiniest species are less than 2cm long.

Habitat

Ocean

Diet

Plankton, fish, crustaceans and other sea jellies

Fun Facts

Sea jellies appeared before dinosaurs. They have been living on Earth for over 650 million years.

The tentacles of sea jellies are used for feeding and defense. With cells containing barbs and venom, these body structures can sting and kill their prey. One of the most venomous species, sea wasps (Chironex fleckeri), can poison a human to death in a few minutes.

Distribution

Found globally in all oceans from tropical to polar waters

Threats & Conservation

Threats

Sea jellies are important members of the marine food web as they act as predators and preys. Climate change and pollution has altered the population sizes of some sea jelly species, thus affecting other members of their ecosystem.