SEA-ANEMONES 325 



The Snake-locked Anemone (Cyliata venusta) has a slender body about 

 two inches high, with a bunch of almost thread-like, grey, writhing tentacles. 

 When compressed (in day time), it is no more than a nondescript yellowish 

 button. 



The Dahlia Wartlet, or THICK- ARMED ANEMONE (Urticina felina) , resembles, 

 when expanded, a cactus Dahlia, its short thick tentacles being banded with 

 scarlet and white. It is found on rock, partially covered with sand and 

 fragments of broken shells. 



The Opelet (Anemonia sulcata) is one of a group which cannot retract the 

 tentacles, and is often found in great numbers. I well remember a rock pool 

 in Guernsey filled with them, looking, with their long flaccid tentacles, like 

 olive-green seaweed. 



Several anemones are parasitic in their habit of attaching themselves to 

 the shells inhabited by hermit-crabs. I have found both the "Parasite" 

 (Cribrina effceta] pale brown, with whitish tentacles on the shell of Eupagurus 

 bernhardus, and also the Cloaklet Anemone (Adamsia palliata] on the shell 

 of another species. They exhibit a remarkable illustration of " partnership " 

 commensalism in nature, for thus the anemone gets the advantage of 

 locomotion, and a share in the crab's booty ; whilst the crab sits secure 

 from marauders under the anemone's shelter, for no fish will touch any of 

 the actinia, and doubtless finds its rider's paralyzing powers useful in numbing 

 its prey. 



The Pimplets are a fairly large group, covered with " pimples." 



The Gem Pimplet (Bunodes verrucosa) is usually partially buried in sand 

 in its rock pool. 



The Globe-horn (Corynactis viridis) is very small, about J of an inch, and grows 

 in colonies, its tentacles having minute knobs instead of coming to a point. 



The Plumose Anemone (Metridium senilis) is recognized at once by its 

 feathered tentacles and tall column. 



The Cave Anemone (Sagartia troglodytes] is common, very variable in 

 colour, but identified by a mark like the letter B on the tentacles. 



Corals. These are closely related to anemones, being, in fact, sea anemones 

 with calcareous skeletons. Few, however, belong to our British waters, 

 though off Devonshire you may find the Common Madrepore, which, when 

 its tentacles are outspread, you would take for an anemone until you touched 

 it, when you would discover it to withdraw into a flinty little tower of lime. 

 Occasionally also you will find the so-called "Dead Man's Fingers," a soft, 

 pinkish, fleshy object, which is a closely allied animal or rather colony of 

 animals living together. 



Hydroid Zoophytes, or POLYPS.* In this section we come to a fresh- 

 water representative, the Common Hydra, which bears some resemblance to 

 the Sea Anemone, in its power to contract into a tiny round lump of jelly, 



* Technically, this includes most of the jelly-fish, etc., which have been dealt with above, and 

 which are, as a matter of fact, transitional phases of the fixed Hydroid Polyp. 



