FISHERY BULLETIN: VOL. 86, NO. 4 



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LU 

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50 



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 ROCK 



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INVEST 



WALK 



FEED 



ACTIVITIES 



Figure 1 . — The percent of observations in which the American lobsters were engaged in each of the listed activities. BR: eelgrass 

 vs. mud, P < 0.001. Invest: eelgrass vs. mud and rock vs. mud, P < 0.05. A'^ varied from 160 to 68. 



strate (Fig. 1). The lobsters in the mud substrate 

 spent a significantly greater percent of their time 

 repairing their burrows than the lobsters in either 

 eelgrass or rocks (arcsine transformation, 1 way 

 ANOVA, Newman-Keuls test, P < 0.001). Based on 

 percent of observations, the lobsters in mud spent 

 significantly less time investigating than did the 

 lobsters in rocks (tests as above, P < 0.05). There 

 was no significant difference, however, between the 

 percent of observations spent investigating in the 

 mud vs. the eelgrass, or in the percent of observa- 

 tions spent investigating in the eelgrass vs. the 

 rocks. 



Based on the percent of observations, the time 

 the lobsters spent resting and pleopod-fanning 

 was considerable (18-45%) in all substrates and did 

 not differ between them. Walking was only observed 

 when a lobster did not have a burrow. Feeding 

 occurred only on the few occasions when some 

 edible object landed close enough to the burrow so 

 that the lobster could reach it without entirely 



leaving its burrow. Twice lobsters were seen catch- 

 ing swimming amphipods at the entrance to their 

 burrow. 



American lobsters were observed creating a cur- 

 rent by pleopod-fanning, which was seen to draw 

 plankton through their burrows. During these 

 periods the lobster stood with its clawed limbs held 

 up and apart. The mouth parts, particularly the sec- 

 ond and third maxillipeds moved rapidly, and the 

 first pair of walking legs were often brought up to 

 the mouth. Occasionally the lobster would jerk for- 

 ward and snap its claws. All of the above-mentioned 

 appendages are covered with various types of setae 

 (Factor 1978), which could help the lobsters to catch 

 the plankton both by "filtering" with their maxilli- 

 peds, claws, and first walking legs, and by seizing 

 the plankton with their claws. These observations, 

 supported by Lavalli and Barshaw (1986) and Bar- 

 shaw (in press) show that American lobsters are 

 able to catch plankton while remaining in their 

 burrow. 



792 



