someone went a little overboard with the silly string
To be fair, the hermit crab here, Pagurus prideauxi, wasn't the party animal here. Those pink strings were secreted from the cloak anemone (Adamsia carciniopados). While they seem fun and festive, the strings are actually poisonous tentacles to protect both the hermit crab and its symbiotic friend!
the anemone protecting its hermit crab pal while he courts a little lady
(photo by Dive Tramp Darryl Mayer)
I always love seeing symbiotic relationships with hermit crabs and anemones. It seems like such a wonderful way for an anemone to get around! The cloak anemone really has it figured out though: while hermit crabs normally have to find larger shells to fit into, and thus have to ditch their old small shells despite any friends they might have picked up, the cloak anemone becomes a sort of protective shell itself for the hermit crab. It does this by creating a chitinous layer called a carcinoecium which helps extend the original shell's coverage!
a sad crabless anemone found on a Scottish beach - note the structure of
the carcinoecium that used to protect a hermit crab's face
Because the cloak anemone adds to the hermit crab's home, the hermit crab never has to worry about finding a bigger shell. That means these crab-anemone pairs are set for life! They're like the Pooh Bear and Piglet of the marine world!
"Silly ol' crab!" - cloak anemone