758 THE LIVING ANIMALS OF THE WORLD 



CHAPTER VI 



CORALS, SEA-ANEMONES, AND 

 JELLY-FISHES 



W 



Photo by W. Saville-Ktnt, F.Z.S. 



A MUSHROOM-CORAL FULLY 



In this condition the coral, or skeleton of the animal, is 



partitions develop upon their surfaces 

 which are merely skeleton-producing 

 sea-anemones, partly secrete within 

 them the symmetrical radiating cal- 

 careous plates so characteristic of the 

 group. 



Some thirty odd species of sea- 

 anemones are indigenous to British 

 waters, and one or more of these 

 will be familiar to most readers. The 

 STRAWBERRY-ANEMONE, clinging to the 

 rocks as a hemispherical lump of 

 crimson, green, brown, or red and 

 yellow speckled jelly when the tide is 

 down, and expanding like a beautiful 

 flower when the waters flow back upon 

 it, is the commonest and in many 

 respects the most beautiful of all, the 

 circlet of turquoise beads, regarded as 

 rudimentary eyes, developed around 

 the outer margin of the tentacles, add- 

 ing a charm possessed by few other 

 species. The DAHLIA-ANEMONE, whose 

 expanded disk and innumerable petal- 

 like tentacles may measure as much 

 as 6 or 8 inches in diameter, is the 

 largest British species. These dimen- 

 sions are, however, vastly exceeded by 



ITH the Sea-anemones and 

 Jelly-fishes almostthe lowest 

 organised group of living 

 animals is reached. As typified by an 

 ordinary sea-anemone, the body may 

 be described as a simple sac, the 

 orifice of which is inverted for some 

 little distance, and held in position 

 with relation to the outer wall by a 

 series of radiating partitions. One or 

 more rows of tentacles, varying in 

 number and character according to the 

 species, surround the mouth of this 

 partially inverted sac. There is no 

 distinct intestinal track, the whole 

 space enclosed within the outer wall 

 and ramifying among the radiating 

 partitions containing the digestive 

 juices. The radiating membranous 

 the reproductive elements, and in the case of Corals, 



EXPANDED 



entirely concealed 



MUSHROOM-CORALS, WITH THE ANEMONE- 

 LIKE POLYP EXPANDED 



Taken through the -water on a coral-reef 



