These corels do not have branched tentacles, they are situated in
two or more circles and the number of tentacles can usually be divided
by six. Hexacorallia can be either solitary or live in colonies.
They can be soft or supported by a calcareous or keratin form.
It is predominently hexacorallia that has built the tropical coral
reefs, where they share the envionment with microscopic algae.
These small algae live in the coral polyps; the coral and algae
live in symbios, they benefit each other. This results in that coral
reefs must exist in relatively shallow water so the algae gets sunlight.
The coral Lophelia pertusa
does not live in symbios with any form of alga, therefore it can
survive in deep water. Lophelia pertusa belongs to the group
true corals. Within the group hexacorallia that exist in
Swedish waters, the anemones (e.g.
anemone) and the
The coral group consists of about 70 specie in Swedish
waters and about 6 000 specie world-wide.
Read more about the different