38 EFFECT OF TRAWLING ON SPONGES AND ZOOPHYTES. 



since the West Sands at St Andrews have been so extensively 

 covered with marine organisms in debris, as, for instance, in 

 the spring of 1857, when the misty air was alive with hooded 

 crows and gulls that fed on the stranded animals. Smaller 

 numbers have been seen, but not the vast numbers of sea-mice, 

 sea-urchins, star-fishes, shell-fishes, zoophytes, crabs, and other 

 forms. 



Besides the evidence (and there is much) of the capture 

 and injury of the invertebrates in the trawl, and the conse- 

 quent removal of part of the food of the fishes at the bottom, 

 it is necessary to show that by constant trawling the sea-bottom 

 is rendered destitute of nourishment for the food-fishes. Nature 

 has provided in the case of such forms a remarkable power of 

 recuperation, and a vitality that renders complete destruction 

 difficult. Thus, the crushing and division of sponges is not 

 followed by the death of all the fragments, and each of those 

 which survives is capable of flourishing as an independent 

 organism (not to allude to the liberation of ova which may 

 happen to be present). The ordinary zoophytes are, as a rule, 

 little affected by being carried on board ship, for, though in 

 the more delicate, such as Tuhularia, the soft polypites may 

 fall off, they are reproduced when returned to the water. The 

 very general provision of free-swimming buds which bear the 

 reproductive elements is also a complete safeguard in the 

 majority of this group, as already stated. Whence do the 

 immense multitudes of the zoophyte (Obelia), which coats with 

 a feathery forest every rope and buoy of the salmon stake-nets, 

 come ? Certainly not from the bottom, but from the myriads 

 of minute pelagic jelly-fishes. Each half of a bisected anemone 

 becomes an independent animal. Again, the sand-dwelling 

 forms, such as Peachia and Edwardsia, the latter occasionally 

 eaten by flounders and dabs, have pelagic young w^hich are 

 swept in every direction by the currents, or sometimes are 

 carried hither and thither attached to the disks of the 

 swimming jelly-fishes. These forms are, indeed, doubly pro- 

 tected, since they live in the sand, and are seldom or never 

 captured by the trawl, while their young are wholly pelagic. 

 'The masses of dead men's fingers (Alcyonium), though 



