SEA LILIES 



Until 1873, sea lilies were believed to be extinct, 

 represented only by fossils in ancient rocks. Then, 

 at the dawn of oceanography, scientists aboard the 

 famous British research ship H.M.S. Challenger be- 

 gan peering at animals from the sea bottom, brought 

 to light in special sampling dredges. Among the col- 

 lections, they found sea lilies still alive. About eighty 

 species are now known to live in the oceans, each 

 animal with an upright, flower-like body supported 

 from the bottom mud by a slender stalk. For them the 

 name of the class Crinoidea is particularly appropri- 

 ate. It comes from the Greek krinos, a lily, and the 

 ending -old, similar to. 



A dredge dragging along the sea bottom on the 

 end of a mile of steel cable is not particularly gentle. 

 It gathers indiscriminately, often breaking off forms 

 of life attached in the ooze. In consequence, no one 

 was certain for many years just how modern sea lilies 

 were anchored. Then, as oceanic telephone cables 

 were raised for repairs, a few stalked crinoids were 

 found attached to them. In most cases they ended in 

 a set of remarkably rootlike extensions, wrapped 

 around the covering of the communication wires. 

 Other sea lilies have a stalk tapering to a curled end, 

 capable of wrapping around solid objects. Or they 

 wear a set of grappling hooks, or a bulblike swelling, 

 or a flat circular disk. All of these are able to resist 

 most pulls that would tend to dislodge the animal 

 from the bottom sediments. 



The stalk itself is supported by a long series of 

 skeletal pieces, giving it a jointed appearance. In 

 living crinoids the stalk may be as much as 20 inches 

 long. In members of one suborder it is ornamented 

 at intervals by short tendril-like extensions (cirri). 

 Apparently these sea lilies sometimes break away 

 from the bottom and thereafter move from place to 

 place, propelling themselves by awkward movements 

 of the branching arms or holding temporarily to firm 

 objects with the cirri. Members of another suborder 

 have no cirri or only rudimentary ones, or cirri only 

 at the attached end of the stem. 



Often the skeletal pieces of the stalk have made 

 highly resistant fossils. The flower-like crown, which 

 is the main body of the animal, is less sturdy. Yet 

 intact fossils have been found with stalks over 70 

 feet long and as many as 200 branches of the five 

 arms. Altogether more than 5000 kinds of extinct sea 

 lilies have been discovered, some of them dating back 

 nearly 700 million years. Probably modern seas are 

 less hospitable to sea lilies and they can be regarded 

 as "living fossils," and perhaps as candidates for ex- 

 tinction. 



Recent work by oceanographers in arctic waters 

 has led to the discovery of a few kinds of stalked 

 crinoids in large numbers at a depth of barely fifty 

 feet. Apparently they take advantage there of the 



256] 



wealth of microscopic food that thrives, in turn, be- 

 cause upwelling currents bring dissolved nutriment 

 from the bottom. 



FEATHER STARS 



Feather stars (Plate 135) are the best-known of 

 crinoids, with about 550 different species. They begin 

 life much as do the sea lilies. But after establishing 

 themselves on the bottom with a slender stem, they 

 break away from its upper end and thereafter lead a 

 free existence. Around the area where the stem was 

 attached, each feather star wears a cluster of cirri 

 and uses these for holding to submerged objects. It 

 then spreads its arms gracefully to the sides, usually 

 curUng their tips upward, and waits while small parti- 

 cles of food drift within range of its cilia-driven feed- 

 ing currents. 



Along the Atlantic coast from the Arctic to Long 

 Island, New York, a grayish feather star with brown 

 bands is found at depths from 90 to nearly 6000 

 feet. It is one of the many species of Antedon found 

 on both sides of the Atlantic, and uses its ten long 

 arms in the characteristic swimming movements. 

 With mouth upward, the arms spread as much as 8 

 inches across. Five of them move down with delicate 

 side branches (pinnules) spread while the alternating 

 five arms rise with pinnules drawn together. If the 

 animal becomes inverted by swimming into a current, 

 it may settle to the bottom and there right itself. The 

 arms on one side are used as levers to raise the body 

 from the surface while the opposite arms reach around 

 and catch hold. 



On the eastern side of the Atlantic, another Ante- 

 don clings to seaweeds in comparatively shallow 

 water, and British trappers of seafoods find it tem- 

 porarily attaching itself to the wicker traps set for 

 crabs and lobsters. In Jamaica and Barbados, British 

 West Indies, a Tropiometra with brownish golden 

 arms clips its cirri to coral rock in water as little as 

 six feet below low tide. These tropical animals are 

 more suitable for a skin diver to examine, for they 

 do not break to pieces (as Antedon does) when 

 touched. If freed from the bottom by chiseling loose 

 the piece of coral, they will let go of their own accord 

 and seize the diver's fingers tenaciously in their cirri 

 as the next best support. 



Feather stars are most abundant in the waters of 

 the Sulu, Celebes, and Banda Seas, in a triangle 

 pointed at New Guinea, Borneo, and the north island 

 of the Philippines. They are fewest in the Atlantic 

 and eastern Pacific, and clearly favor rocky bottoms 

 or coral reefs in preference to sand or mud. The 

 smallest adult feather stars, 1 inch across, live in 

 the West Indies and in abysses of the Pacific Ocean. 

 The largest is Heliometni glacicdis, reaching 3 feet 

 in diameter in ice-cold water at the west side of the 

 Okhotsk Sea north of Japan. 



[continued on page 273 ] 



