14 man's influence on annelids and crabs. 



degree. Thus the Beche de mer (Trepang) fishery of Australia 

 and the South Sea Islands seems to show no sign of exhaustion 

 — notwithstanding the eager search for these holothurians as a 

 favourite article of diet for the Chinese. Doubtless the pelagic 

 larvae, like those of the brittle- stars and sea-urchins, enable 

 them to survive. Indeed it would appear that the echinoderms 

 in which the larvae are reptant (and not pelagic) are fewer in 

 numbers than those provided with free-swimming young. The 

 group as a whole is important and furnishes food for many 

 invertebrates, fishes and gulls. 



Amongst the annelids there are a few forms which have 

 been persistently sought from early times by man for bait, e.g. 

 the lobworm (Arenicola marina). On limited areas of sand or 

 muddy sand numerous fishermen have almost daily plied their 

 spades, and while, perhaps, the examples may not be so 

 abundant as at first, there is, as a rule, no lack of them on 

 most beaches. The lobworm, indeed, is an instance of a marine 

 form — placed within easy reach of the instruments of capture — 

 which has resisted the attacks of man, probably because a 

 sufficient stock of ripe examples and the ver}^ jo^^^g are 

 covered at all times by the tide. The Palolo of Samoa and 

 Tonga, so much esteemed as food by the natives, and captured 

 in its season with the utmost keenness, is still as abundant as in 

 former generations. This annelid lives amongst the coral reefs 

 of these islands, becomes pelagic for the sake of discharging its 

 eggs into the surrounding water, and is then captured in great 

 quantities for food. Man has persistently taken as many of each 

 species as he could, yet both maintain their abundance. 



The enormous numbers of pelagic larval annelids, in suc- 

 cessive swarms, which throng the sea throughout the greater 

 part of the year, together with such adults as Tomopteris and 

 the Ghcetognath, Sagitta, show in this group alone a great 

 perennial source of nourishment. The demersal adults are 

 everywhere a favourite food of fishes, which find them where 

 man cannot. 



In no class is the boundless wealth of the sea in all 

 latitudes more conspicuous than in the crustaceans or crabs. 

 It is necessary, however, to consider them in two groups, viz., 



