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Williams, Austin B. Mud Shrimps, Upogebiidae, from the Western Atlantic (Crustacea: Decapoda: Thalassinidea). Smithsonian Contributions to Zoology, number 544, 77 pages, 31 figures, 1993.-Mud shrimps, Upogebiidae, found in the western Atlantic between Massachusetts, U.S.A., and southern Brazil are reviewed. Twelve species described previously from this region are recognized: Pomatogebia operculata (Schmitt), Florida through Caribbean region, and off Espfrito Santo, Brazil, in stony corals; Upogebia acanthura (Coelho), ranging from Florida, U.S.A., through Caribbean region, and from mouth of Amazon River to Cabo Frio, Brazil, living in sponges; U.

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Three species of Western Atlantic penaeid shrimps-Penaeus setijerus, P. axtecus, and P. duorarum-were allowed a free choice among five types of substrates in partitioned experimental troughs. The substrates used were beach sand, shell-sand, muddy sand, sandy mud, and loose peat. Each species was tested separately, and each experiment was replicated once. Results of the experiments showed that distribution of the shrimps on the different substrates was not random. In each experiment departures from the expected distribution were statistically significant.I'. duorarum occurred most often on shell-sand. P. aztecus and P. setijerus were found most frequently on the softer, muddier substrates--loose peat, sandy mud, and muddy sand.Food content in the bottom materials may have been a confounding factor, but the results indicate attraction to substrate aside from the possible attraction to food.Water volume, or pore space, and the compaction of bottom materials, may influence the degree of burrowing.