THE STARFISHES OF SOUTHERN CALIFORNIA 



By Albert B. Ulre;y, A. M. 



Director of the Venice Marine Biological Station of the 



University of Southern California. 



'T^HE starfishes (Asteroidea) of Southern California have 

 -*- received comparatively little attention from students of 

 marine life. Without access to extensive monographs it has 

 been impossible to make even approximate identifications of 

 the commoner forms off our coast. The starfishes afford 

 abundant illustrations of a wide range of biological problems. 

 At ,this time especially we are warranted in asking first wheth- 

 er these forms have an important economic relation. 



It is well known to biologists and those concerned with 

 the oyster industry that the starfishes constitute one of the 

 worst pests found on oyster beds. Most starfishes are car- 

 nivorous by preference, feeding largely on the barnacles and 

 mollusks attached to the rocks or among which they live. 

 While they are very destructive to mussels and oysters they 

 feed also on limpets, chitons and small snail-like gasteropods. 



The destructive action of starfishes in oyster beds on the 

 Atlantic coast becomes at times a serious menace. There a 

 single small species (Asterias forbesi) is responsible for the 

 damage done. On the Pacific coast we have about forty re- 

 lated species with similar habits and these species are much 

 larger, some of them two feet across. It will be seen that 

 the starfishes on the Pacific coast must always be a great 

 hindrance to the cultivation of oysters, mussels, etc., except 

 where the water is too brackish for starfish life. 



The Feeding Habits of Starfishes. In the case of the 

 commoner forms of starfish found attached to rocks there will 

 be seen in a groove on the ventral side of the ray a large 

 number of strong, tube-like muscular feet each with a perfect 

 sucker at the tip. With these the starfish adheres firmly to 

 the rocks, moves from place to place or opens the shell of its 

 prey. Usually there are four close rows of such suckers the 

 entire length of the ray ; estimating 200 to a ray there would 

 be 1000 on a five-rayed form. In the larger five or six-rayed 

 species there may be 4000 to 8000 present. The number is 

 enormously increased in the large twenty-rayed or twenty-four 

 rayed forms such as the "sun star" Pycnopodia helianthoides, 

 probably 40,000 or over. 



In feeding on an oyster too large to swallow entire the 

 rays are wrapped about the victim and with their numerous 

 suckers a long and steady pull opens the shell. These star- 

 fishes are able to evert the large bag-like stomach and wrap 

 it around its prey until digestion is completed, when the 



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