flesh in their diet. They scavenge from the tide hue to 

 at least twenty thousand feet below the surface, and 

 are found on every type of bottom in all seas at all 

 latitudes. A few burrow, but most creep over and 

 cling to seaweeds, sponges, hydroids, corals, and 

 other attached forms of life. 



Most serpent stars are either male or female, and 

 they free their reproductive products into the sea. 

 Some do brood their eggs, providing this parental care 

 until the young are miniatures of the parent. Some 

 serpent stars are hermaphrodites, with both ovaries 

 and testes. A number of six-armed species reproduce 

 by transverse division of the body, followed by re- 

 generation of the missing parts by each half. 



Almost all of the sixteen hundred diflferent species 

 of serpent stars have unbranched arms. One order is 

 exceptional: the basket stars (Plate 134). These 

 creatures live in deeper water, and somehow control 

 a profusion of arm branches, walking about on the 

 branch tips or coiling them about submarine growths. 

 Gorgonocephalus, the gorgon's head basket star, is a 

 big one. with a body as much as 4 inches across and 

 arms repeatedly branching to a total length of I foot 

 or more. If a living specimen is placed in fresh water, 

 it will die in an expanded position, completely re- 

 laxed. Then it can be preserved to show the great 

 maze of slender branchlets. Otherwise it curls up in 

 a confused mass. 



Serpent stars with unbranched arms seldom have 

 a body disk more than 1 inch in diameter ( Plates 

 131-133). A good many of them have remarkably 

 extensive geographic range, some being truly cosmo- 

 politan in coastal waters. The long-armed serpent 

 star Ainphipholis squamata is one of the most wide- 

 spread from the subarctic to the subantarctic. It is 

 particularly abundant around the British Isles as a 

 grayish white or faintly bluish denizen of tide pools. 

 It is hermaphroditic and broods its young internally, 

 hence is viviparous. 



Ophiactis savignyi is circumtropical, and is dis- 

 tinctive in having square teeth. Small, young individ- 

 uals with six arms can often be found in the cavities 

 of sponges; there they reproduce by transverse di- 

 vision of the body. Eventually, however, they reach 

 a larger size and become solitary. Then, after a final 

 fission, each half grows only two new teeth and two 

 new arms, becoming a five-armed serpent star. 

 Thereafter it is an adult, reproducing only by sexual 

 means. 



Some serpent stars are quite colorful and show a 

 range of coloration from one individual to another. 

 This is particularly obvious in the common daisy brit- 

 tle star OphiophuUs ciciileuta found from Long Island 

 Sound to the Arctic, and in the spiny serpent star 

 Ophiothrix angiilata of shallow waters from Chesa- 

 peake Bay to the West Indies and Rio de Janeiro. 

 The first-named actually spreads downward to a 



The five-holed sand dollar Mcllita tcsludinata has five 

 rays and a covering of movable spines that identify it 

 as a flattened relative of sea urchins. It digs into 

 sandy bottoms along the Atlantic coast of America 

 and in the West Indies. (Delaware Bay. William H. 

 Amos ) 



depth of over six thousand feet — ten times as deep as 

 O. angiilata is found. 



O. acideata has a body just under 1 inch across 

 and arms to 3'/2 inches long, and may be red or blue 

 on the body, deeper red or green or brown banded 

 with white on the arms. O. angiilata seems always to 

 show a color difference between the banded arms 

 and the body: the latter may be red, pink, yellow, 

 brown, green, blue, or purple — almost the full spec- 

 trum among the individuals in a single tide pool. 



At night a number of dilTerent serpent stars can be 

 found along the shore because the arms luminesce. 

 Ophiacantha hidentata, whose arms often appear to 

 be knotted, is dark brown by day but bluish gray in 

 the dark; it inhabits the Atlantic and Pacific, as far 

 south as Portugal and South Carolina, California and 

 Korea; it is commonest between thirty and fifteen 

 thousand feet below the surface. Ophioscolex gla- 

 cialis, whose 5-inch arms and 1-inch body are cov- 

 ered with a thick skin, varies from purple to yellow 

 in daylight; at night its body is invisible but the arms 

 are a bright violet, contrasting with muddy bottoms 

 from Virginia to Greenland. 



[285 



