They tend to be pale in appearance when young, but mature to have a brightly purple-blue (some yellow) colored bell.

These jellyfish drift closer to the shore to catch the large abundance of plankton with their tentacles.

[3] The jellyfish live off a diet of phytoplankton or zooplankton as well as the eggs and larvae of other aquatic animals such as fish.

The species specifier originates from the French naturalist Lamarck (Latin name form: Lamarckius).

The medusae bud and loosen from the mature polyps between January and March around the British Isles and southern North Sea.