tube-feet by having particularly large mouths, and 

 engulf astonishing numbers of small animals. One in- 

 dividual of A. aiiramiciciis from the Mediterranean 

 was found to have swallowed ten scallops, six Tellina 

 clams, five tusk shells (scaphopods), and several 

 snails. Another species in the same region dines reg- 

 ularly on young sea stars, brittle stars, bivalves, snails, 

 segmented worms, and assorted crustaceans. Snail 

 shells regurgitated by Astropecten stars along the Pa- 

 cific coast of America are so intact and empty that 

 hermit crabs adopt them while house-hunting. 



Leptycluister arctictis has a larger body disk than 

 members of Psihister or Astropecten and differs from 

 them in lacking spines on the marginal plates. Fully 

 grown individuals seldom exceed 1 V-i inches in diam- 

 eter, but they are well worth examining closely since 

 this is a sea star that may brood its young. It is found 

 in cooler coastal waters of both the North Atlantic 

 and North Pacific. 



Brooding in these stars seems related to low tem- 

 peratures and, as among sea cucumbers, to echino- 

 derms that produce larger eggs than is usual, hence 

 with plenty of yolk as stored food. In Leptychaster 

 uber of the northwest Pacific and L. kergiielenensis 

 from close to Antarctica, up to thirty young are car- 

 ried in depressions of the greatly stretched aboral sur- 

 face of the parent. 



Edged sea stars whose tube-feet have suction tips 

 are better able to hold a shellfish while attacking it as 

 food. The largest group with this characteristic (fam- 

 ily Goniasteridae) includes perhaps the most bril- 

 liantly colored sea stars of Australian waters, and 

 has representatives in many other parts of the world 

 as well. Thick, massive plates border the broad-based 

 arms, and the whole aboral surface is commonly 

 roofed by a mosaic of skeletal pieces under a smooth 

 or granular skin. Mediaster aequalis is studded above 

 and below with compact little paxillae, giving the ap- 

 pearance of everlasting flowers in a honeycomb pat- 

 tern. It is found in shore waters along the Pacific 

 coast from Alaska to California. 



The largest sea star of the Atlantic coast of Amer- 

 ica is Oleaster reticiilatiis of Florida, the Bahamas, 

 and the West Indies. The name reticiilatiis refers to 

 the network pattern evident on the upper surface, 

 where the parchment-thin skin sags a little between 

 the mesh of the bar-shaped skeletal plates. Like oth- 

 ers of its family, it is a massive animal, quite thick in 

 the middle. Specimens measuring 16 to 20 inches 

 across are often displayed as trophies of the sea. They 

 may be almost any color from deep purple through 

 maroon, orange, green, or bluish, with bright yellow 

 points where the skeletal plates join one another at 

 prominent rounded spines. O. nodosus, brilliant in 

 red and blue, is equally admired in the Indo-Pacific. 



The marginal plates in Linckia (Plate 129) are 

 much less evident on the more-or-less cylindrical 



arms. The whole body is clothed in rounded or squar- 

 ish plates, often with a pebbled surface. L. giiildingi 

 inhabits tropical waters of all oceans. L. colomhiae, 

 which grows to as much as 4 inches across, can be 

 found on rocky shores from Los Angeles, California, 

 to the Galapagos Islands off Ecuador. All of these 

 animals show spectacular powers of regeneration, for 

 even a piece of an arm less than V2 of an inch long 

 can reorganize itself into a whole new sea star. At 

 least part of the body disk must accompany a whole 

 arm for such a fragment of any other kind of sea star 

 to regenerate the missing parts. 



THE SPINY SEA STARS 



A connoiseur of sea stars recognizes those with 

 conspicuous spines over much of the upper and lower 

 surfaces as being very different from any of the edged 

 sea stars. These features are marks of a spiny sea star 

 (order Spinulosa), the skeleton of which usually 

 consists of a network of limy bars or of plates over- 

 lapping one another. The boundary between oral and 

 aboral surface is rarely evident on the body or arms, 

 and while the tube-feet always have suction tips, ped- 

 icellariae are rare. 



One of the commonest spiny sea stars of western 

 Europe and the Mediterranean is Asterina gihbosa, 

 which is covered on both surfaces by tufts of small 

 spines. It is found along the Atlantic coast of Africa 

 as far as the Azores, and is known to vary its diet of 

 moUusks with meals on sponges and sea squirts. 



The red or orange sea bat, Patiria miniata (Plate 

 126), is almost equally familiar along the Pacific 

 coast from Lower California to Alaska. Its oral sur- 

 face is decorated with tufts of spines in the form of 

 little fans fitted together, whereas the aboral surface 

 is granular, with curved plates forming an attractive 

 pattern. It seems to be particularly omnivorous, often 

 eating seaweed, sponges, sea urchins, squid eggs, or 

 spreading its thin surface against surfaces upon 

 which diatoms are growing. It will digest them away 

 from even the glass side of an aquarium. 



Sometimes the appetite of a spiny sea star cannot 

 be predicted from an examination of its body. The 

 broadly pentagonal Anseropoda placenta of western 

 Europe and the Mediterranean is a burrowing species 

 of wafer thinness. Yet it engulfs other echinoderms, 

 snails, little clams, and a great variety of small crusta- 

 ceans — even hermit crabs. It seems impossible for 

 any animal to eat so much and stay so thin. 



The blood star, Henricia sangiiinolenta (Plate 

 125), is seldom more than 3 inches across, but its 

 rich red color and graceful pointed arms make it a fa- 

 vorite with beachcombers from Greenland to Cape 

 Hatteras on the western side of the Atlantic, and to 

 the Azores on the eastern side. Some individuals are 

 rose-colored, others orange, or purple, or even mottled 

 with creamy yellow. The arms are always smoothly 



278' 



