(photos of Nadya Sanamyan, Russia: specimens from Kamchatka, NW Pacific)
Metridium senile fimbriatum is a Pacific subspecies of widely distributed northern species Metridium senile. Specimens of Metridium senile fimbriatum are typically smaller than giant specimens of Metridium farcimen. Both species often occur together. Specimens with fighting tentacles (photo below) are much more common in Metridium senile fimbriatum than in Metridium farcimen, although M. farcimen also may possess them.
Species delimitation in the genus Metridium is still poorly understood, and it is not quite clear if all described subspecies and other forms really different, and if they are separate species or not.
Taxonomy:
Phylum Cnidaria
Class Anthozoa
Order Actiniaria
