Zoological Introduction to
Between Pacific Tides
by
Edward F. Ricketts
1936
Probably the zoologist familiar with Pacific invertebrates will find this less accessible as a manual and reference, possibly even more cumbersome some and inexact, than if we had built it according to the usual scheme. The tyro, however, and the arm-chair general reader will find it surely more convenient and a lot more interesting. Advantages to classes in marine biology and to the visiting zoologist will be apparent also. And the professional worker can realize, extenuatingly, that inexactness and inconsistency are the prerogatives also (and more particularly) of the animals themselves - as though they were conspiring against one's attempt to catalog them neatly! (the reality of natural things as contrasted with our intellectual need for realizing all phenomena in discrete states).
The attempt throughout has been to construct an account interesting to the layreader, and useful alike to the zoologist. Probably we shall have succeeded only partially in travelling that knife edge without leaning on the one side toward technicalities, which must bewilder the layman, or on the other toward inaneness, to which in popular writings the biologist will be sensitive.
Since its first draft several years back, the manuscript has ben used in actual practice up and down the coast. Some of its deficiences have been corrected. Some are just now being realized. Others probably we have not even yet discovered.
Occasionally distribution can be indexed by some of the lesser factors, salinity (Puget Sound barnacles), insolation (protection from or exposure to sun, as in British limpets), etc. But there are hundreds . . .
On the whole, it will probably be granted by most field zoologists that competent observers might even now construct fairly accurate zonal graphs in which the tide level station of many of the commoner forms could be plotted, based on the means of many counts and measurements over widespread areas. Obviously, we cannot make even a pretense of having done this in the tentative and approximate arrangement which follows, but which, nevertheless, may prove both stimulating and suggestive.
The limitations of any tool will become apparent sooner or later, and we should emphasize at the start that it would be inadvisable for the collector to attempt to identify his catch accurately solely by means of this classification. This depsite the Cabrera 1932 law of ecological incompatibility wherey "In the same locality . . . directly related animal forms always occupy difference habitats or ecological stations . . . related animal forms are ecologically incompatible and incompatibility is the more profound the more directly they are related." (quoted from Biol. Abstracts, March 1935, #4488). ................ Any ecological classsification will be inexact, suggestive rather definitive; a given animal may occur in several environments, nd ven its primary assignment to noe may not be certain until documented by quantitative methods. However, ecological arrangement ought rather to be used guardedly and for what theya re wroth with due regard for their limitations. Only the less obvious exceptions will be found confusing. The extreme exceptions are obvious. Deep water crinoids or scaphopods for instance seldom will be found along shore, altho no doubt such things will have happened.........
Authority fo interesting or radical statements may sometimes offer difficulties to the zoologist-reader. We attempt to show major citations ............
No keys have been provided for the obvious reasons that: (a)satisfactory ones can be constructed at present for only a few of the groups on this coast, due to the lack of correlated information on taxonomy, distribution and/or quantitative natural history, even where the group is known; (b) many of the local invertebrates, even some of the common forms, are still undescribed or in a chaotic state taxonomically; and (c), even where they could be constructed, comprehensive keys, unless very fully annotated and explained, would be useless to the beginner.