62 MADRAS FISHERIES BULLETIN VOL. XIV, 



TANK No. 2. 



Various kinds of sharks and of their smaller relatives, the 

 dogfishes, share this tank with ray-fishes and the snaKe-like 

 members of the eel family. The sucker-fishes also are usually 

 found in this tank. 



As is well known, tropical seas swarm with many kinds of 

 sharks, some attaining enormous dimensions. Fortunately man- 

 eating species do not come near the shore in places where 

 surf bathing is indulged in. They keep usually to deep water but 

 the entrances to rivers and harbours, and anchorages frequented 

 by steamers, have an attraction for them because of the quantity of 

 garbage to be found there. The larger and more dangerous sharks 

 are omnivorous and none too dainty in their tastes. On one 

 occasion I found an enormous mass of feathers in the stomach of 

 one— it surely must have made a meal of a feather pillow! The 

 smaller species are often most exclusive in their dietary ; some 

 feed entirely upon crabs, others upon shellfish. All are usually 

 most highly infected with parasites, tape-worms chiefly ; books 

 have been written on the wonderful adaptations evolved by these 

 worms for retaining their hold upon the wall of their host's 

 intestine. Hooks, suckers and imbedded bulbous heads are the 

 chief devices employed ; their variety is infinite, their suitability 

 amazing for the purpose to be attained. And the names given by 

 zoologists to these strange creatures are by no means the least 

 wonderful of the strange things belonging to them. Imasjine 

 being christened Hori/ellobotlirinui cobrafonnis or Myzophyllohothriiiiii ! 



But to return to the sharks and their relatives. These form a 

 separate and strongly marked-off division of fishes, differing from 

 all others in having a series of openings, called gill-slits, along 

 each side of the neck. In the case of rays, which are flattened or 

 disc-shaped fishes evolved from a shark-like ancestor, the neck 

 being lost, gill-slits are found on the under side of the b )dy some 

 little distance behind the mouth. Another characteristic of the 

 shark and ray family is the cartilaginous or gristly nature of the 

 skeleton ; there are no hard limy bones as in the bamin, sardine, or 

 whiting. The form of the tail is also peculiar. 



The ordinary shark is a handsome fish in the beauty of its 



"lines" and the sinuous grace of its movements. Usually their 



colours, like those of sea-snakes, are various shades of grey upon 



the back, white on the belly. But some of those forms which 



