Common jellyfish  (Aurelia aurita)

The common jellyfish is common and widespread (2).

As its name suggests, the common jellyfish (Aurelia aurita) is the most common jellyfish species on British shores (2). The body is a saucer shaped 'bell', which is colourless except for four obvious violet gonads visible in the centre of the disc (2). The outer edges are fringed with many small tentacles, and four stocky 'arms' surround the mouth (2).

The common jellyfish is found around all British coasts (2). It is a northern hemisphere species, found in the Atlantic, Pacific, and Indian Oceans (3).

You can view distribution information for this species at the National Biodiversity Network Gateway.

Typically found close to the coast, the common jellyfish can also be found in estuaries (2).

The common jellyfish is carnivorous, and feeds mainly on a variety of planktonic species such as molluscs, crustaceans, young worms and copepods (3). The plankton is caught in a layer of mucus that covers the jellyfish. Tiny hair-like structures called 'cilia' on the body of the jellyfish produce currents by beating. These currents transport the captured plankton towards the edge of the 'bell', where it is removed with the arms and passed to the mouth (2). The tentacles around the margins of the bell and the arms bear stinging cells, which are occasionally used to catch small fishes and other prey (2).

In the common jellyfish, the sexes are separate and fertilisation occurs internally; the sperm is taken into the female's body via the mouth (2). The fertilised eggs undergo development in pockets in the arms that surround the mouth. The free-swimming larvae (known as 'planulae' larvae) are released during autumn; after some time these larvae settle and develop into tiny sessile animals ('scyphistomae'), which reproduce asexually and release free-swimming tiny immature jellyfish (called 'ephyrae'), which feed on plankton and become mature after around 3 months (2).

The common jellyfish is not currently threatened.

No conservation action has been targeted at the common jellyfish.

There may be further information about this species available via the National Biodiversity Network Gateway.

For more on the common jellyfish, see:

• Animal Diversity Web - Aurelia aurita, moon jelly:
  http://animaldiversity.ummz.umich.edu/accounts/aurelia/a._aurita.html