40 ON POLYPS. 



them shrink from the touch ; and if rudely assailed, they com- 

 pletely contract their bodies so as to take the appearance of a hard 

 coriaceous mass, scarcely distinguishable from the substance to 

 which they are attached. 



(55.) It is in seizing and devouring their prey however that the 

 habits of the Actiniae are best exemplified ; they will remain for 

 hours with their arms fully expanded and motionless, waiting for 

 some passing animal which chance may place at their disposal, and 

 when the opportunity arrives, are little inferior to the Hydrse in their 

 voracity or powers of destroying their victims. Their food generally 

 consists of crabs or shell-fish, animals apparently far superior to 

 themselves in strength and activity, but even these are easily over- 

 powered by the sluggish yet persevering grasp of their assailant. 

 No sooner are the tentacles touched by a passing animal than it is 

 seized, and held with unfailing pertinacity ; the arms gradually 

 close around it ; the mouth, placed in the centre of the disc, ex- 

 pands to an extraordinary size ; and the creature is soon engulph- 

 ed in the digestive bag of the Actinia, where the solution of all its 

 soft parts is rapidly effected, and the hard undigestible remnants 

 speedily cast out at the same orifice. 



The Actiniae, although exceedingly voracious, will bear long 

 fasting :* they may be preserved alive for a whole year, or per- 

 haps longer, in a vessel of sea- water, without any visible food ; but 

 when food is offered, one of them will devour a crab as large as a 

 hen's egg, or two muscles in their shells : in a day or two the 

 shells are voided through the mouth, perfectly cleared of the soft 

 parts which they contained. 



(56.) The Actiniae, like the Hydras, possess the power of chang- 

 ing their position : they often elongate their bodies, and, remaining 

 fixed by the base, stretch from side to side as if seeking food at a 

 distance ; they can even change their place by gliding upon the 

 disc which supports them, or detaching themselves entirely, and 

 swelling themselves with water, they become nearly of the same 

 specific gravity as the element which they inhabit, and the least 

 agitation is sufficient to drive them elsewhere ; Reaumur even 

 asserts that they can turn themselves so as to use their tentacles as 

 feet, crawling upon the bottom of the sea ; but this mode of pro- 

 gression has not been observed by subsequent naturalists : when 

 they wish to fix themselves, they expel the water from their dis- 



* Encyclopaedia Londinensis, art. Actinia. 



