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low saucer, with extremes of size from 3 inches to 2 

 feet; but most are from 6 to 10 inches in diameter. 

 The tentacles are short and extremely numerous, 

 forming a fringe around the margin. Readily visible 

 through the top of the milky white or bluish umbrella 

 are four horseshoe-shaped reproductive organs, of- 

 ten colored violet or pink. From the underside hang 

 four long, tapering, somewhat stiff mouth lobes. This 

 is a relatively harmless jellyfish, and it feeds on mi- 

 nute organisms, chiefly copepods, which are collected 

 in mucus on the umbrella surfaces and then licked 

 off by the mouth lobes and carried by ciliary currents 

 to the mouth. 



Dactyloiuelra qiiinqueciirha, with a long name 

 and a bad reputation for painful stings, belongs to 

 the same genus as certain dangerous jellyfishes of the 

 tropical Pacific. (A Pacific species is shown in Plate 

 7.) It is seen from the Azores and New England to 

 the tropics, and from West Africa, the Indian Ocean, 

 the Malay Archipelago, and the Philippines to Japan. 



The common sea blubber, Cyanea ccipillata, whose 

 huge arctic variant has been referred to several times, 

 is also called the pink jellyfish — probably by people 

 who have not felt its fiery stings. In England it is "the 

 hairy stinger" or "the lion's mane," the last name 

 serving in the Sherlock Holmes story about a fatal 

 case of Cyanea poisoning, "The Adventure of the 

 Lion's Mane." Most individuals are not over 3 feet 

 in diameter, with tentacles extending down for 75 

 feet, and 12-inch disks are most common. The color 

 showing through the thick disk varies from a rosy 

 pink to a brownish purple, and the yellow or reddish 

 tentacles hang down in great bunches, the gaps be- 

 tween bunches revealing the frilled purplish mouth 

 lobes. Cyanea capillata is abundant in the cool and 

 cold waters of both the Atlantic and the Pacific 

 oceans. Other stinging species are found in the tropi- 

 cal and temperate Pacific. This is another of the 

 scyphozoans that are known to luminesce. 



THE MANY-MOUTHED JELLYFISHES 



There is no widely used common name for this 

 group, and it helps little to say that the technical 

 name, Rhizostomeae, means "root-mouthed." The 

 rhizostomes have no single large mouth as do other 

 jellyfishes, but feed through numberless small open- 

 ings in the mouth lobes. Each of the four lobes is sub- 

 divided, elongated, lobed, and folded, so that in some 

 members they suggested a bundle of eight long roots 

 hanging from the lower surface. There are no tenta- 

 cles around the margin, and these jellyfishes feed 

 mostly on microscopic organisms drawn into the tiny 

 mouths by ciliary currents. The 7-inch Stomoloplnis 

 of the southeastern American coast and the larger 

 Rhizostoma of European waters have a high, mush- 

 room-shaped umbrella. Most interesting is Cassio- 

 peia, common in quiet, shallow mangrove bays in 



Florida and in the tropics. Thousands of them lie 

 disk to disk, on their backs, the voluminous and 

 branching mouth lobes exposed to the gentle food- 

 bearing currents that sweep across. This relaxed 

 feeding habit also displays to the sun the myriads of 

 green cells that live in the tissues. Presumably the 

 green guests utilize nitrogenous and gaseous wastes 

 of the jellyfish and in return make it possible for Cas- 

 siopeia to live densely crowded in stagnant waters. 



Sea Whips, Sea Fans, 

 Anemones, Corals, and 



v^ [1 1 ei S ( Class A nthozoa or A ctinozoa ) 



The anthozoans ("flower animals") are most fa- 

 miliar as the solitary sea anemones of temperate 

 seashores, or as the corals, sea fans, and sea whips 

 known to most people from their beautiful dried skel- 

 etons. This is by far the most conspicuous and most 

 successful class of coelenterates, comprising more 

 than six thousand species, all of them marine and 

 most of them living in shore or shallow waters. All 

 are cylindrical polyps, with no trace of a jellyfish 

 stage in the life history. A little free-swimming plan- 

 ula larva serves to distribute many of those that live 

 permanently attached. A few, like the sea anemones 

 and sea pens, do move about at times. The free end 



The many-mouthed jellyfish, Rhizostoma, feeds 

 through countless small openings in the pendant 

 mouth lobes. (Naples Aquarium. Ralph Buchsbaum) 



