. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 184 JAN IJ- DEMBOWSKI. Besides photo- and thigmotaxis there is a strong hydrotaxis, the crab striving towards the moisture. There exists also a very marked tendency of hiding itself in the sand. Especially in females we may see often a behavior distinctly different from the ordinary burrowing. It consists in a quick pressing of the body in the sand. As the friction is very strong the animal succeeds only in hiding the thorax while the legs of one side of the body remain uncovered. In this position the crab may remain motion-
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 184 JAN IJ- DEMBOWSKI. Besides photo- and thigmotaxis there is a strong hydrotaxis, the crab striving towards the moisture. There exists also a very marked tendency of hiding itself in the sand. Especially in females we may see often a behavior distinctly different from the ordinary burrowing. It consists in a quick pressing of the body in the sand. As the friction is very strong the animal succeeds only in hiding the thorax while the legs of one side of the body remain uncovered. In this position the crab may remain motion- less for hours and such a behavior certainly has some biological significance as very little is seen of the crab, the legs having a marked protective coloration. The consistency of the ground has also some influence on the choice of the spot where the work is started. If we make a shallow hole in the sand Uca will choose it as the starting point. All those "taxies" and strivings, and many more, determine the actual behavior and referring the activities of a crab to some particular tropism is rather a poor explanation. However, at last the animal starts its work. To simplify the nomenclature I shall use roman numbers for the legs of the side of the large claw of the male, and the arabic 1-5 for the legs of the opposite side. Thus I. means the large chela, i the small one. At the very beginning of the work the side 1-5 is usually directed towards the wall of the jar, straightly or obliquely, and usually this side begins to dig. The legs 2, 3 and 4 which are. FIG. 2. The second leg from the side, st, sternum ; xpi>dit; ''• basipodit; i. ischiopodit; m, moropodit; ca. carpopodit; />, propndit; d, dactylopodit. There is no movable articulation between h and /. Articulations p-d, m-ca and c-b work in the same plane, others at right angles to tin-in. bent in the articulations mero-carpopodit and dactylo-propodit at the normal position of the body become somewh
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
