Between Pacific Tides

Edward F. Ricketts
Stanford University Press
circa 1940s Photos of Ed Ricketts

Click here for enlargement of above photographs and written passages.

Compiled by
Robert 'Roy' J. van de Hoek
Field Biologist & Geographer
Sierra Club, Wetlands Action Network, National Audubon Society

The enormous wealth of life that occurs between the upper and the lower limits of the tide is a phenomenon of intense interest to the biologist and to the layman alike. Here strange plants and bizarre, brilliantly colored animals grow in such abundance that the most casual visitor to the seashore cannot fail to notice some of them. Almost invariable his curiosity is aroused: Is that gorgeous flower-like thing in the tide pool a plant or an animal? What is it called? What does it eat? How does it defend itself and reproduce its kind? Will it hurt me if I touch it?

And while the visitor is puzzling over his first sea anemone, a score of crabs may scurry away at his footfall or may rear up and offer battle in defense of life and liberty. When he turns to watch the crabs he may see a bed of urchins, their bristling spines half concealed by bits of seaweed and shell. He may stoop to pick up a snail, only to have the creature roll from the rock at the approach of his hand, tumble into a pool, and scramble awayat a very unsnail-like pace. He hears scraping sounds and clicks and bubbling, perhaps sharp cracks like pistol shots. Jets of water shoot up. Everywhere there is color, life, movement.

In shore, our visitor to a rocky shore at low tide has entered possibly the most prolific life zone in the world - a belt so thickly populated that often not only is every square inch of the area utilized by some plant or animal but the competition for attachment sites is so keen that animals settle upon each other - plants grow upon animals, and animals upon plants.

To supply such a person with as much as possible of the information . . . [to be continued]

The shore topography of the Pacific coast differs considerably from that of the Atlantic coast, and this factor, since it determines the conditions of life of the shore animals, often produces animal communities that seem strange to Eastern students. More obviously on the Pacific coast than on the Atlantic coast, the three co-ordinate and interlocking factors that determine the distribution of shore invertebrates are: (a) the degree of wave shock, (b) the type of bottom (whether rock, sand, mud, or some combination of these), and (c) the tidal exposure.

Considering these in turn:
(a) On the Pacific coast the degree of wave shock . . .

(b) In considering the types of bottom this intergradation is too obvious to stress beyond remarking that in the cases of innumerable variations between sand, muddy sand, sandy mud, and mud we have begged the question somewhat by using only two headings - sand flats and mud flats - leaving it to the judgement of the collector to decide where one merges into the other.

(c) The third important aspect of habitat, tidal exposure, has to do with the zoning of naimals according to the relative lengths of exposure to air and water (bathymetrical zoning) - in other words, the level at which the animals occur. A glance . . . With these provisos, then, our system of zonation (figure 1) is equally applicable to San QuintÓn Bay, where the extreme range of tides is less than eight feet, and to Juneau, where it is more than twenty-three feet.

These three aspects of habitat - wave shock, . . .

I. Protected Outer Coast. Under this division . . .

II. Open Coast. Entirely unprotected, suf-swept shores while by non means . . .

III. Bay and Estuary. Animals of the sloughs, enclosed bays, sounds, and estuaries, where the rise and fall of the tides is not complicated by surf, enjoy the ultimate . . .

IV. Wharf Piling. In addition to many animals which will be found elsewhere, wooden pilings support numerous species, such as the infamous Teredo, which will seldom or never be found in any otehr environment. The nature of piling fauna justifies . . .

Absolute beginners will do well to devote their primary attention to large, common, and spectacular animals which may easily be identified merely by reference to the group of illustrations concerned with the given type of shore. For instance, the beginner who for any reason would familarize himself with a starfish found on surf-swept rocks can refer almost instantly to the illustrations of open-coast animals, all of which are grouped together in Division II. Here approximate identification can be ascertained and reference will be found to a fairly comprehensive statement of habits and natural history of the indicated starfish in the main text; citations of more complete and detailed accounts may subsequently be looked up in the bibliography and systematic index.

A. Rocky-Shores
From the standpoint of the shore collector the rocky tide flats of the protected outer coast comprise the most important of all regions. . .
Moreover, it is highly important that the collector, in the interests of conservation, replace carefully all such rocks in their depressions; otherwise many of the delicate bottom animals are exposed to fatal drying, sunlight, or wave action. Whoever doubts the necessity for such care should examine a familiar intertidal area directly after and again a few days after it has been combed by a biology class that has failed to observe the precaution of replacing overturned rocks. At first the rocks will simply look strange and scarred. In a few days whole colonies of tunicates and solitary corals and tube worms will be found dead, and a noticeable line of demarcation will set off the desolate area from its natural surroundings. It takes weeks ormonths for such a spot to recover.

Annotated Systematic Index
and Bibliography
[The main accounts only are indexed here, by section number; references to susidiary accounts will be found in the alphabetical index. Bibliographical entries to 1936, when the library of E.F. Ricketts was destroyed by fire, are believed to include all important items. Since 1936 it has proved impossible to give sustained attention tot he literature of the field and entries are far from comprehensive.]

. . . References:
Laubenfels, M. W. de. 1932. The marine and fresh-water sponges of California," Proc. U.S. Nat. Mus., 81: 1-140. Bibliography lists the four lambe papers and the Urban paper.