288 TEXT-BOOK OF ZOOLOGY 



more than from 1 to 2 per cent, of the total quantity of the fish. Cod, 

 dog-fishes, whales, seals, and marine birds, annually destroy a vastly 

 larger number than man. What inconceivably vast quantities of the 

 fish must therefore be contained in the sea ! (Form a chain from the 

 following links: Diatom, copepod, herring, cod (which see), man. 

 What would happen if the first, or one of the first links in this chain 

 were to perish ?) 



Allied Species. 



The Sprat (C. sprattus) has nearly the same range as the herring. 

 Its length does not exceed from 4 to 6 inches (see illustration, p. 284). 

 This fish is also caught in large quantities and is put on the market both 

 fresh and smoked. The place of the sprat in the seas of the North is 

 filled in the Mediterranean and the coastal waters of South-Western 

 Europe by the Sardine (C. pilchardus), which is largely consumed, 

 salted or pickled or preserved in olive-oil. In the same seas we also 

 find the Anchovy (Engraulis encrasichohis). This fish is preserved in 

 salt or pickled with a large quantity of pepper. 



The Common Eel (Anguilla vulgaris). 

 (Length up to 5 feet.) 



During the daytime the eel lies hidden in holes in the banks of 

 rivers or ponds, or it buries itself in the sand or mud. Hence its colour, 

 like that of all bottom fishes (compare tench and sheat-fish) is dark, and 

 often even quite black. At the approach of dusk it goes in search of 

 food, which consists of fish, crustaceans and other small aquatic animals. 

 Occasionally it will also feed on carrion. The body is snake-like, and 

 the tail flattened and bordered by a fin-band (compare with newt and 

 tadpole of frog). Its progress, which is effected by undulations of the 

 body and strokes of the tail, though not awkward, is nevertheless slow 

 for a predaceous fish. Hence it does not fall on its prey with a sudden 

 rush like the pike, etc., but tries to surprise its victims in their recesses, 

 such as holes in the bank, under roots, etc. By its shape and the 

 suppleness of its slippery body it is well adapted for penetrating into 

 such narrow spaces. The mouth, with its wide gape and equipment of 

 teeth, points it out as a carnivorous animal (see pike). 



Well known though the eel is itself, its mode of reproduction is still 

 in many points unascertained. It is, however, now established that the 

 full-grown eels migrate to the sea usually in autumn, and that the 

 young fish, measuring from 1 to 3 inches, return in spring in innunaer- 



