. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SNAPPING SHRIMP AND UNDERWATER NOISE 127 ever, they are very unlike the common shrimp. The snapping shrimp family Crangonidae (Alpheidae, see Rathbun, 1904) comprises about 27 genera and numerous species. Of these only the species of two genera, viz., Crangon (also called Alpheus by many authors) and Synalpheus, are capable of vigorous snap- ping. In the literature there are recorded about 215 species of Crangon and 150 species of Synalpheus. Two species of these genera are shown in Figures 1 and 1000 10000 FREQUENCY IN
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SNAPPING SHRIMP AND UNDERWATER NOISE 127 ever, they are very unlike the common shrimp. The snapping shrimp family Crangonidae (Alpheidae, see Rathbun, 1904) comprises about 27 genera and numerous species. Of these only the species of two genera, viz., Crangon (also called Alpheus by many authors) and Synalpheus, are capable of vigorous snap- ping. In the literature there are recorded about 215 species of Crangon and 150 species of Synalpheus. Two species of these genera are shown in Figures 1 and 1000 10000 FREQUENCY IN CYCLES PER SECOND FIGURE 3. Average ambient noise spectrum over shrimp bed. The snapping habit Studies of most species of these two genera have been based on preserved speci- mens ; consequently, the snapping has not been observed directly in many species. The claw structure, however, indicates that all the species do snap to some extent. The species range in size from about 2 cm. to a giant species, C. strenuus, attain- ing a length of 8 cm., but it is clear that size is not necessarily correlated with the noise produced. The few direct sound measurements available of isolated speci- mens indicate, for example, that Synalpheus lockingtoni may produce a louder snap than its larger relative Crangon dentipes. The average peak pressure level of Crangon for a distance of a meter was 115 db above ; whereas it was about 124 db for Synalpheus. While the difference may be real, the present observations are too few, and the spread too great, to confirm this. The habit of snapping is associated with defensive and offensive activities. In closing the snapping claw, a vigorous jet of water is produced by means of a plunger arrangement described below. This sudden gush of water serves to frighten away enemies approaching too near. The antagonist may also be driven. Please note that these images are extracted from scanned page images that may have been digitally enhanced for
Size: 1973px × 1266px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
