. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic. Oceanography. 470 DEPTHS OF THE OCEAN generally find the most abundant animal life among the algae in localities where wave-action is most effective. Most of the non-attached forms are in no way directly dependent upon the algae-vegetation. It will be evident that attachment to fucus and laminaria is not biologically essential, if we bear in mind that the same animal forms which attach themselves to these plan
. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic. Oceanography. 470 DEPTHS OF THE OCEAN generally find the most abundant animal life among the algae in localities where wave-action is most effective. Most of the non-attached forms are in no way directly dependent upon the algae-vegetation. It will be evident that attachment to fucus and laminaria is not biologically essential, if we bear in mind that the same animal forms which attach themselves to these plants occur also on rocks and stones. The vegetation merely increases the area available for the attached forms. Nor is any particular plant essential for any particular species of animal. No doubt on the Norwegian west coast Laomedea flexuosa and Clava squamata nearly always attach themselves to Ascophyllum, while Obelia geniculata and some others prefer laminaria, but this is chiefly owing to the tides. On the Skagerrack coasts, where tides are inconsiderable and irregular, we find even in the fucus belt forms like Coryne (see Fig. 333), Tubularia,) and Obelia geniculate though on the west coast of Nor- way they grow only among the laminaria and at a lower depth. These forms cannot stand exposure for any length of time, and they are therefore not to be found in places where the ebb regularly goes back a long way. The forms met with in the tidal area cannot, however, be in any way dependent upon the ebb-tide for their existence, seeing that they occur numerously also on the coasts of the Skagerrack, where tides are scarcely felt. Instances of this are furnished by Clava, Campanularia flexuosa, and Dynamena pumila, but the fact that these forms are able to withstand exposure for considerable periods of time makes it possible for them to occupy a far more extensive area than would otherwise be the case. So far as the structure of their organs is concerned, the unattached forms in t
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