Left-right tendency in the hermit crab, Calcinus herbsteii.

Abstract

The tendency of an animal to turn to the right or left when given a choice is studied here with reference to the hermit crab. The term "left-right tendency" is used in preference to "handedness" since the latter term might be thought to imply the greater use of the right or left claw instead of the general rightward or leftward tendency of the animal when confronted with a choice. Relatively little attention has been given to this problem in so far as the invertebrates are concerned. The work carried out to date has been summarized by Wile 1 who directs attention to the fact that organisms with a left spiral structure tend to move to the right in the ratio of 10 to 1 or greater while animals with a right spiral structure move left predominantly in the ratio of about 2.3 to 1.While hermit crabs can hardly be considered to be spirally constructed yet they do inhabit the shells of animals which are so constructed. For instance, all hermit crabs used in the present experiment were found living in dextrally coiled shells, the majority in Nerita picea, Turbo intercostalis, and Peristernia chlorostoma although twelve other species were also represented. Most marine shells are coiled to the right and hermit crabs show a corresponding modification and degeneration of the appendages of the right side.Under the circumstances would a hermit crab turn predominantly to the right or to the left when the experimental arrangements were such as to offer equal chances?The species chosen for the experiment was Calcinus herbsteii de Man, an attractively colored hermit crab, sometimes reaching 3 inches in length, which is not uncommon near the Marine Laboratory of the University of Hawaii at Waikiki Beach where the experiment was conducted. For this type of experiment C. herbsteii offered the advantage of being an active crustacean; most true crabs would be less satisfactory for this work. C. herbsteii has a large left claw and a relatively small right one; no exceptions to this statement were found although a large number were examined. The one large claw is used to block the opening into the shell into which it fits closely, thus acting as an operculum.The apparatus used consisted of a series of Y-shaped runways made from glass and held together by plastic cement. Each runway was painted black, the floor being sanded while the paint was still wet in order to provide traction. Each was built to the same specifications (6$ inches long with passages \\ inches wide) and when in use was placed in a large tray filled with sea water. The water depth was always sufficient to cover both the hermit crab and its shell. In each case the double end of the "Y" faced the window. Extreme 1 Wile, Ira S.: Handedness Right and Left. Boston, 1934.

Do turning biases by the 7-spot ladybird, Coccinella septempunctata, increase their foraging efficiency?

“…comm.) Turning biases have also been reported for Aleochara bilineata (Coleoptera) (Putnam, 1962), Calcinus herbsteii and Clibinarius zebra (two species of hermit crab) (MacKay, 1945(MacKay, , 1947 and Heliodrilus (Annel-ida) (Swartz, 1929). There have also been a few reports of turning biases on flat surfaces, e.g., desert ants (Wehner & Srinivasan, 1981) and Pediculus humanus (Anoplura) (Wigglesworth, 1941) and in other environments e.g.…”