curved from aboral to oral surface, and the groove 

 containing the tube-feet is usually narrow. 



Both H. sangiiinolenta and H. leviiisciila on the Pa- 

 cific coast of America stay hidden in dark crevices 

 during the winter months while they brood their rel- 

 atively large eggs. Henricia larvae omit the usual free- 

 swimming larval stage, and remain concealed among 

 the parent's incurved arms until they have trans- 

 formed into miniature stars, ready to glide on their 

 own along the bottom. 



The sun stars Crossaster and Sohister have a broad 

 body disk and many arms. Crossaster papposiis 

 (Plate 127), found in the Pacific Ocean along coasts 

 as far south as Vancouver Island and in the Atlantic 

 to New Jersey on the west and the English Channel 

 on the east, is easily the handsomest of them. It may 

 have from eight to fifteen arms, each tufted conspicu- 

 ously with spines. The whole aboral surface wears a 

 sunburst of color perhaps more striking than on any 

 other echinoderm. 



Solaster endiva, by contrast, has slender arms and 

 no raised tufts of spines. It lives on both sides of the 

 Atlantic in cool water, and is usually a bright purple. 

 On Pacific coasts it is represented by S. dawsoni. Sun 

 stars are voracious creatures, eating large numbers of 

 smaller sea stars as well as sea anemones, bivalves, 

 and snails. Like Henricia. they have no free-swim- 

 ming stage, but develop directly. Older individuals 

 have more arms than younger ones. 



Pteraster iniliuris is one of several cushion stars 

 found in shore waters of Scandinavia, the British 

 Isles, down the Atlantic coast of America to New 

 Jersey, and along cooler shores of the Pacific. The 

 pinkish red body is covered by a membranous skin 

 draped from circlets of slender spines, as though it 

 were a tent roof. The membrane extends as a web 

 around the short, bluntly rounded arms, which may 

 span 6 inches. The skin over the aboral surface ac- 

 tually conceals a cavity used as a brood pouch for the 

 young and in respiration. Water enters it through 

 pores below, and emerges through a large cloacal 

 opening near the middle of the upper surface. 



THE FORCEPS-CARRYING 

 SEA STARS 



The special enemies of shellfishermen are sea stars 

 which, upon close inspection, prove to bear pedicel- 

 lariae raised above the surface on short stalks able to 

 turn in various directions. Most of these forceps-car- 

 riers (order Forcipulata) have long, rounded arms 

 and a small body disk. They include many of the most 

 persistent destroyers of clams, mussels, and oysters. 



The forceps-carriers include the familiar stars of 

 wharf pilings and tide pools all over the world. As- 

 terias ainiirensis inhabits the Pacific coast from 

 Alaska to Korea, A. vulgaris the Atlantic coast from 

 Labrador to Long Island, A. forbesi from Maine to 



Sun stars are denizens of shallow temperate seas. 

 Their amis var) in number, usually from seven to 

 thirteen, but may total as many as seventeen. The 

 exposed surface often wears a sunburst of color. 

 (Maine. Ralph Buchsbaum) 



the Gulf of Mexico, and A. ruhens (Plate 124) the 

 northern shores of Europe. All of them have a rough 

 body surface and four rows of tube-feet in the groove 

 below each arm. They also have two types of pedicel- 

 lariae: some with straight forceps, and others of a 

 cross-bladed type. A. vulgaris in Maine sometimes 

 reaches a span of 17 inches. 



In opening a shellfish, these stars mount it with the 

 mouth opening directed toward the place where the 

 clam would gape if the mollusk did not clamp its 

 valves together. Then, with almost every tube-foot 

 aflfixed to one valve or the other, the sea star applies 

 the force of its body muscles. A pull of 7 to 10 pounds 

 has been measured, tending to open the shell. 



Contrary to widespread belief, the sea star need 

 not wait for its victim to tire. A force of this size is 

 sufficient to bend the shell of clam or oyster, making it 

 gape a fraction. Even a hundredth of an inch is 

 enough for the sea star. Through the narrow slot it 

 slips its even thinner, everted stomach and proceeds 

 to digest the shellfish deep in the shell. For much of 

 the time the sea star does not even bother to hold the 

 valves apart. It lets them clamp on the extruded stom- 

 ach except at such times as a stream of liquefied prod- 

 ucts of digestion are ready for transfer into the sea 

 star's body. 



Not all forceps-carriers have the same tastes. On 

 the Pacific coast of America, Astrometis seriulifera 

 is expert at feeding on the large chiton Stenoplax 

 clinging to the rocks. Pisaster brevispimis on sandy 

 bottoms hunts for sand dollars, and the flavor of an 

 approaching star of this kind is distinctive enough to 

 sand dollars that they will cease feeding and burrow 



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