Bougainvillia britannica is a marine invertebrate, a species of hydroid in the suborder Anthomedusae.

It has long pedicels and medusa buds develop in clusters on branched stalks.

[1] B. britannica is found in the north east Atlantic Ocean and the North Sea, particularly round the shores of Britain and Ireland, Belgium and the Netherlands.

[1] The B. britannica hydroid buds and forms medusae by asexual reproduction.

When these mature, sexual reproduction occurs, the fertilised eggs settle out and new hydroids are formed.