SWIMIVIING ANIMALS 95 



suckers by means of which a fish can hold on to a solid 

 object. The common sucker {Lepadogaster) found in our 

 rock-pools has a suctorial disc formed by a pair of fins on 

 its under surface. In this case the resemblance of the 

 sucking organ to the original fins can still be seen. But any 

 fin-like appearance is completely lost in the case of the 

 sucking disc of the Remora. This fish bears upon its 

 head an object that looks more like the rubber sole of 

 a sand-shoe than anything else. It is a very powerful 

 sucker and with it the Remora fastens itself to the bodies 

 of sharks and so gets rapidly transported from place to 

 place and incidentally is able to pick up any remnants of 

 food that the greedy host may drop. That this sucking disc 

 is really a transformed back-fin has been discovered by an 

 examination of the very early stages of the fish ; when it is 

 only about half an inch long it possesses a normal back -fin 

 like any other fish, but as it grows this fin gradually moves 

 fonvard until it comes to lie on top of the fish's head, and in 

 the meantime its structure is altering to that curious 

 ridged form which acts as such an efficient sucker. The 

 sucking action of this disc has been disputed, and it is 

 thought by some that the clinging effect is brought about 

 chiefly by friction. 



The habit of the sucking-fish of fastening on to other fish 

 has been taken advantage of by man, who actually makes 

 use of the Remora to catch other fish. The method is 

 practised by natives of such widely separated districts as 

 the Caribbean Sea, Chinese waters and the Torres Straits. 

 Although being used for catching certain fish such as 

 sharks they are chiefly used for capturing turtles. The 

 sucking-fish has a thin line attached to its tail. On 

 sighting a turtle the natives row up to within fairly easy 

 reach of it and then throw the Remora towards it. The fish 

 immediately swims to the turtle and attaches itself to its 



