ACTINIIO^.- 



-RADIATA.- 



-CORALl.IPUOKA. 



401 



Family— ACTINIID.E (Sea Anemoues). 



The animals belonging to tliis famil." are composed 

 of a flesliy body resembling a truncated cone seated on 

 a flat plain base, and generally attached by a glutinous 

 secretion to stones, rocks, or shells, &c., in the sea. 

 The centre of the upper surface is dimpled wilh the 

 opening into the mouth, and this aperture is furnished 

 with numerous simple, tubular, retractile lentacula, 

 placed in one or more series round it. The body is 

 variously coloured, and the tentacula, brilliant with lively 

 hues and disposed in circles, give a very striking re- 

 presentation of the petals of a beautiful flower. It is 

 from this resemblance that they receive the names of 

 Sea Anemones, and so like are they to a flower that, 

 as Mr. Gosse tells \is, bees liave been arrested by the 

 resemblance while flying over them, and have been 

 seen to dart tlirough the wat»r to reach them. A 

 cluster of these elegant creatures, seen a few feet 

 below the surfoce, in clear still water, with their 

 tentacula fully displayed, presents a striking appearance ; 

 and travellers who have watched them in tropical 

 seas speak entliusiastically of their beauty. These 

 tentacula are furnished with the peculiar nettling ap- 

 paratus described in Medusae. 



The movements of the Adinim are very slow. Some 

 indeed are permanently attached, but others are only 

 temporarily adherent, to foreign bodies. When these 

 move ihey glide along w'ith an impcrcep ible motion, 

 or they detach themselves altogether from their resting 

 place, previously distending the body with water, to 

 render it more buoyant, and then allowing themselves 

 to be carried along with the random motion of the 

 waves. They are very sensitive to external irritations 

 and to atmospheric changes, closing themselves up in 

 cloudy and stormy weather, and expanding themselves 

 again when the sky is serene. The family is repre- 

 sented, in Plat J 2, fig. 13, by a common British and 

 very pretty species. Actinia {Crihriyia) diantlius, the 

 white animal flower. 



In the family Zoanthidce the animals have a hard, 

 cartilaginous outer skin, often strengthened by the 

 deposition of earthy grains within its surface. In the 

 genus Zoanthus the body is elongated, conic, and 

 pedunculated. The animals are distinct from each 

 other, but several individuals arise from a common 

 base, which is in the form of a creeping stem. The 

 family is represented in Plate 2, fig. 12, by an exotic 

 species, Zoantlius Ellisii. 



CORALLIPnORA {Stony Corals). 



By far the gi-eater number of Zoanthoid polypes, as 

 they grow, deposit in the cellular substance of the flesh 

 of their back an immense quantity of calcareous matter, 

 which enlarges as the animal increases in size, and, in 

 fact, fills up all those portions of the substance of the 

 animal, which, by the growth of new parts, are no 

 longer wanted for its nourishment ; and in this manner 

 they form a strong and hard case, amongst the folds 

 of which they can contract themselves, so as to be pro- 

 tected from external injury, and by the same means 

 Vol. II. 



form for themselves a permanent attachment, wliich 

 prevents their being tos.sed about by every wave of the 

 element in which they live. The stony substances are 

 called corals, and their mode of formation causes them 

 exactly to represent the animal which secretes them — 

 thus giving origin to the numerous sub-divisions in their 

 classification. 



The formation of the various coral islands, and the 

 vast reefs which act as barriers, and which fringe the 

 shores of many continents, has given rise to a good deal 

 of conjecture and discussion. As described by various 

 voyagers and naturalists, they form exceedingly beauti- 

 ful and interesting sights. Immense spaces of the 

 ocean are studded with islands and reefs formed by 

 these little Anthozoid polypes. As Jlr. Darwin says, 

 we feel surprised when travellers tell us of the vast 

 dimensions of the Pyramids and other great ruins; bnt 

 how utterly insignificant are the greatest of these when 

 compared to those mountains of stone accumulated by 

 the agency of various minute and tender animals! Tlje 

 Lagoon islands, or " Atolls," are often many leagues in 

 diameter; the Radack group alone forming an iiregular 

 square, five hundred and twenty miles in length, ai.d 

 two hundred and forty broad; the barrier reefs on the 

 coast of Australia extend nearly a thousand miles; 

 and the fringing or shore reefs to nearly as much. 

 Such a result from such a cause is marvellous ; — 



" Compared with this amazing edifice, 



Kaised by the weakest creatures in existence, 



What are the works of intellectual man ? 



Towers, temples, palaces, and sepulchres. 



In honour of the living and the dead, 



What are they V — fine wrought miniatures of art. 



Dust in the balance, atoms in the gale, 



Compar'd with these achievements in the deep, 



Were all the monuments of olden time. 



In days when there were giants on the earth: 



Babel's stupendous folly, though it aimed 



To scale heaven's battlements, was but a toy, 



The plaything of a world in infancy — 



The ramparts, towers, and gates of Babylon, 



IJuilt for eternity — though where they stood 



Ituin itself stands still for lack of work, 



And Desolation keeps unbroken Sabbath — 



Great Babylon, in its full moon of empire, 



Kven when its ' head of gold ' was smitten off. 



And from a monarch chang'd into a brute — 



Great Babylon was like a wreath of sand 



Left by one tide, and cancell'd by the next. 



Egypt's dread wonders, still defying Time — 



Egypt's gray piles of bieroglyiihic grandeur — 



Her Pyramids would be mere pinnacles, 



Her giant statues, wrought from rock of grauite, 



But I'Uny ornaments for such a pile 



As tliis stujjendous mound of Catacombs, 



Eill'd with dry mummies of the builder worms," 



Various theories have been produced to account fur 

 the formation of these in)mcnse strt'.ctures. One of 

 these is, that the coral i.^lands or "Atolls" are based on 

 submarine craters, and that they rise from profound 

 depths till they reach the surface. But to tliis and 

 other theories there are great objections. Tliis is not 

 tlie place, nor have we space to devote to tlie consider- 

 ation of this question ; but from the observations of Mr. 

 Darwin and others, it would appear that the animals 

 forming coral reefs or rocks cannot exist or flourish at 

 greater depths than from twenty to thirty fathoms. 

 From this fact he concludes " it is absolutely cettaiu 



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