Abstract
NEST-BUILDING AMPHIPODS.—Mr. S. J. Smith, in a memoir on some amphipods described by Thomas Say (Trans., Connecticut Acad., July, 1880), states that the tubes which certain species make to live in are to a great extent formed of pellets of their excreta. In 1874 he watched carefully the process of constructing the tubes in several species of Amphipoda. Microdeutopus grandimanus (M. minax, Smith) was a particularly favourable subject for observation. When captured and placed in a small zoophyte trough with small branching algæ, the individuals almost always proceeded at once to construct a tube, and could very readily be observed under the microscope. A few slender branches of the alga were pulled toward each other by means of the antennae and gnathopods, and fastened by threads of cement spun from branch to branch by the first and second pairs of peraeopods. The branches were not usually at once brought near enough together to serve as the framework of the tube, but were gradually brought together by pulling them in and fastening them a little at a time, until they were brought into the proper position, where they were firmly held by means of a thick network of fine threads of cement spun from branch to branch. After the tube had assumed very nearly its completed form, it was still usually nothing but a transparent network of cement threads woven among the branches of the alga, though occasionally a branch of the alga was bitten off and added to the framework: but very soon the animal began to work bits of excrement and bits of alga into the net. In this case the pellets of excrement, as passed, were taken in the gnathopods and maxilli-peds, and apparently also by the maxillae and mandibles, and broken into minute fragments and worked through the web, upon the outside of which they seemed to adhere, partially by the viscosity of the cement threads, and partially by the tangle of threads over them. Excrement and bits of alga were thus worked into the wall of the tube until the whole animal was protected from view, while, during the whole process, the spinning of cement over the inside of the tube was kept up. When spinning the cement threads within the tube the animal was held in place on the ventral side by the second pair of gnathopods and the caudal appendages, the latter being curved beneath the anterior portion of the pleon, and on the dorsal side by the third, fourth, and fifth pairs of peraeopods extended and turned up over the back, with the dactyli turned outward into the web. The spinning was done wholly with the first and second peraeopods, the tips of which were touched from point to point over the inside of the skeleton tube in a way that recalled strongly the movements of the hands in playing upon a piano. The cement adhered at once at the points touched and spun out between them in uniform delicate threads. The threads seemed to harden very quickly after they were spun, and did not seem even from the first to adhere to the animal itself.
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Biological Notes . Nature 22, 594–595 (1880). https://doi.org/10.1038/022594b0
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DOI: https://doi.org/10.1038/022594b0