1 56 A BIOLOGY OF CRUSTACEA 



and removing the males which come to pay their attentions to her. 



A unique method of catching crabs is reputed to be used on 

 certain Pacific islands. The natives are said to fear the nipping 

 powers of the Robber Crab, Birgus latro, but they also prize it as 

 food, particularly the abdomen, which contains a lot of fat. This 

 crab climbs trees, and when one is found up a tree the natives place 

 a girdle of grass around the trunk at a considerable height above 

 the ground. When the crab reaches the girdle on its way down it 

 thinks that it has reached the ground and lets go of the tree. The 

 fall stuns the crab, and the natives capture it. It is difficult to say 

 how true this story is. The Robber Crab seems to be a particularly 

 good subject for travellers' tales. One of these is the way in which 

 it is supposed to open coconuts. The crab is stated to begin by 

 tearing at the husk, always at the end under which the three eye- 

 holes are situated. When this region is exposed the crab hammers 

 one of the eye holes with its chelae until an opening is made. Then 

 the crab turns round and puts its thin back legs, which bear small 

 chelae, into the hole and removes the white material from inside. 

 This tale has appeared in many otherwise reputable books, but a 

 recent analysis of the evidence (Reyne, 1939), shows that the crab 

 does not behave in this way. It does feed to some extent on coco- 

 nuts, but only on those which have been damaged, in fact the 

 natives on Guam use a coconut with a hole in it as bait for this 

 crab. The Robber Crab feeds on other things such as carrion. Doubt 

 may also be cast on the grass girdle method of capture, since Reyne 

 found that the crab could fall from a height of five metres without 

 harm. 



Traps of various kinds are used for crabs and lobsters. The prin- 

 ciple behind these is that access to the inside of the baited trap 

 should be easy, and exit extremely difficult. The Cornish crab-pot 

 is a familiar type; the Scots creel is a more convenient shape for 

 stowing in a small boat. Local variations in the detailed structure 

 of these traps are found. On the west coast of Scotland the creels 

 are often 'one-eyed' — having only one entrance; in the Orkneys 

 the creels have an additional anti-escape device in the form of a 

 flap which open inwards when the lobster enters and closes behind 

 it. The California spiny lobster fishermen use a type of creel made 

 of wooden slats, without any netting. In Southern California it is 

 reckoned that a crew of two with a fifteen-foot skiff can operate 

 about 75 traps a day. The spiny lobster fishery is based entirely on 

 the sale of living or freshly cooked specimens; pickling in any 



