Foraging behaviour of an excavating predator, the red rock crab (Cancer productus Randall) on soft-shell clam (Mya arenaria L.)
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| Authors: | Smith, TE; Ydenberg, RC; Elner, RW |
| Year: | 1999 |
| Journal: | Journal of Experimental Marine Biology and Ecology 238: 185-197 |
| Title: | Foraging behaviour of an excavating predator, the red rock crab (Cancer productus Randall) on soft-shell clam (Mya arenaria L.) |
| Abstract: | We investigated the influence of soft-shell clam (Mya arenaria) burial depth on red rock crab (Cancer productus) foraging behaviour. In laboratory tanks, crabs searched for and excavated clams buried at depths of 5, 10, and 15 cm. Handling time of prey was partitioned into excavation time, breaking time, and eating time. Prey excavation formed 23% of mean total handling time (mean 8.2 min total 35.7 min(-1)) at 5 cm prey depth, 62% at 10 cm depth (mean 49.3 min total 79.5 min(-1)), and 73% at 15 cm depth (mean 93.5 min total 128.2 min(-1)). Mean excavation time for clams increased at a rate of 8.3 min cm(-1) of depth; clam profitability (energy intake per unit handling time (J s(-1))) decreased with burial depth. Predation rates decreased with prey burial depth. Often crabs gave up attempts to excavate a clam, and abandonment frequency and excavation time before abandonment increased significantly (p < 0.05) with burial depth. Our findings confirm earlier studies which indicate that burial depth affords an important refuge from crab predation, significantly increasing prey handling time and decreasing the profitability of individual prey. (C) 1999 Elsevier Science B.V. All rights reserved. |
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