Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: Actiniaria
Family: Metridiidae

Genus/species: Metridium senile

GENERAL CHARACTERISTICS: M. senile is colored white, cream, tan, orange or brown. Height to 5 cm (2 inches). Tentacular crown diameter to 25 cm (9.75 inches), Up to one hundred small, slender tentacles give a feathery (plumose) appearance.

 Metridium senile 3074666433_ab584596e9_o

DISTRIBUTION/HABITAT: Southern Alaska to Southern California and both Atlantic coasts. Found live in groups of up to 500 specimens per square meter at depths to 166 m (540 feet). M. senile lives on rocks, shells, wood pilings and stony breakwaters in bays and harbors in the low intertidal and subtidal zones. Plumose anemones crawl slowly along the substrate by muscular waves of the pedal disk.

DIET IN THE WILD: Mostly small zooplankton, though they may also eat small benthic polychaetes, fish, and squid.

REPRODUCTION: Protandric hermaphrodite starting life as one sex and changes to the other when it is older. Eggs or sperm develop in the gonads embedded in the mesentery that lines the coelom. They are ejected through the mouth, and when fertilised develop into planula larvae which settle and become juveniles.

They also reproduce asexually by binary fission, budding and fragmentation.

PREDATORS: Nudibranch Aeolidia papillosa (on small individuals), and the seastars Hippasteria spinosa and Dermasterias imbricata, which can eat even quite large individuals.  Attacked individuals may detach and drift to a new location.

Location: California Rocky Coast and tide pool


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