Cnidarians Stinging cells Polyps and medusae Two layers No head Hydrozoa Jellyfish Anthozoa Picture of systematics Other names

Anthozoa An approx. half-meter block of Lophelia pertusa, and a close-up of some "cups" where the mouth and tentacles are situated. Corals are cnidarians. When we think of the word coral, our thoughts drift to tropical seas and coral reefs with colourful fish. Along the Swedish coast corals are also quite common and there are even coral reefs in the Koster fjord in northern Bohuslän on the Swedish west coast! It is Lophelia pertusa that has built these reefs in fairly deep water, at least 85 m.     Corals can be soft or have varying types of hard skeletons. Corals do not have a medusa stage. The polyps themselves produce the eggs and sperms. Many corals are luminous. Alcyonaria This group of corals is easily recognized because of its eight tentacles around the mouth. The tentacles sit in a circle around the edge and have small branches. Alcyonaria corels have a horny or leather-like skeleton supported by calcareous pins. They live in colonies. Examples of these corals in Swedish waters are alcyonacidas (e.g. dead men´s finger), sea fans and gorgonacidas (e.g. sea-pens). Page 8 of 13

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson