The ocean / By P. H. Gosse.

  • Gosse, Philip Henry, 1810-1888.
Date:
[pref. 1845]
Catalogue details

Licence: Public Domain Mark

Credit: The ocean / By P. H. Gosse. Source: Wellcome Collection.

    284/388 (page 262)
    It may excite surprise, that the openings in the reefs are not gradually filled up, in those cases where no stream of fresh water flows into the sea. But it appears, that the presence of any sediment is so annoying to the animals, as to prevent their acting with energy. This may be produced in various modes ; there are many animals which feed on the living coral ; Mr. Darwin observed two Parrot-fishes (Scarus), one outside and the other inside the reef, both engaged in devouring it; many small mollusca penetrate into it, and the Sea-cucumbers (Holuthuria;), which are very nu- merous and large, are continually nibbling at it. The rolling of dead masses by the surf must also chafe away particles continually, and the presence of the deposited sand thus formed is doubtless one reason why the coral grows languidly within the lagoon; whereas the abraded atoms on the outside are at once washed off by the waves, and sink to the bottom of the ocean. Now, the water which is continually thrown into the lagoon by the surf breaking over the reef, can find an outlet only through the openings of which I am speaking; and thus a constant current is maintained through them, and particularly at the sides, where the opposing waves offer less resistance, carrying out some of the sediment, and depositing it in its course on the coral margins of the aperture. The coral sand made by these abraded fragments, is quickly cemented by the influence of the sun into a solid mass, where exposed to the air; and it is, perhaps, owing to this property, that the numberless little islets are form-