35 



fishing is at any rate as effective in the case of the first men- 

 tioned, so that it is doubtful at least if the prohibition of the 

 fisherman's operations really afford any material protection. It 

 is different of course when the crawfish is large enough to escape 

 the octopus. Another serious enemy of the young crawfish 

 at this early stage of Hfe is probably the "horse-fish 

 (Agriopus), which seems to live chiefly on small Crustacea 

 about the size of these small forms. This large toothless 

 fish can extract crabs, etc., from their hiding places by the 

 sudden protrusion of the mouth parts, which form a powertul 

 suction tube. 



The so-called " sea-snake " (Bdellostoma) is said by some 

 to attack the crawfish. It is frequently found along with 

 the crawfish in the fishermen's nets and certainly devours 

 dead crawfish. It is the experience, however, of most fishermen 

 that it is not a serious enemy of the crawfish, if one at alL 

 Certainly there was no disposition observed on the part ot 

 these " snakes " to attack five crawfish when kept together 

 in the same tanks at the Marine Laboratory at St. James . 

 Some of the more adventurous of the young crawfish indeed 

 attacked these animals when first placed in the tanks with 

 them. They were, however, very soon disconcerted by the 

 shmy matter given out by the " snakes," and, in fact, had 

 some difficulty in getting rid of it, as it clung to their tentacles 

 and body and caused them great trouble for some time after 

 their ill considered attack. The presence of the sea-snakes in 

 the crawfish nets is therefore doubtless due to their being 

 attracted by the fish bait. 



Fish generally do not seem to be serious enemies ot the 

 crawfish. In the tanks they usually avoided it, and, when 

 they happened to approach too closely, they at once started 

 off as soon as they came in contact with the long spiny 

 tentacles, which were thrust out in their direction. 



Amongst sea birds the " Bank Duiker" (Phalacrocorax) is 

 said to attack and devour crawfish. 



While the adult crawfish is thus well provided with means 

 of defence, it is different when the shell is cast and the animal 

 is at the mercy of most of the other sea animals. It is then 

 very wary and conceals itself as much as possible amongst 

 rocks or in sand. It employs the same means of defence 

 however, when approached, bringing forward its tentacles 

 and keeping them projected towards the source of danger 

 Of course they are then quite soft and flexible though in 

 appearance in their normal condition. Apparently this 

 is undetected by some of their enemies, as theyohave been 

 observed to rapidly move off on the approach of the threaten- 

 [C.P. 5-'i3-] 



