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Jellyfish – introduction Cnidaria
Fast facts
- Jellyfish are not fish – they're related to sea anemones and corals, so it's easier to just call them "jellies"
- Jellies don't have eyes and use sunlight as a compass
Jellyfish are ancient, simple creatures.
Although referred to as “jellyfish”, these strange creatures are not fish at all, but are related to sea anemones and corals.
Jellyfish or “jellies” are simple creatures. Although they have a mouth, they have no anus, liver, pancreas or intestine. They have no lungs or gills – the walls of the body and tentacles are so thin that oxygen and carbon dioxide can easily pass through.
Jellyfish have no eyes, but use light-sensitive organs on the outer layer of their bodies to distinguish between light and dark. They orientate themselves in the water by using sunlight as a compass.
Jellyfish use their tentacles as touch receptors to capture food and to detect vibrations in the water caused by fish, crabs and other animals.
Read more about various species of jellies:
Download the document below to read more about jellyfish.