ZOOLOGICAL SOCIETY 

 BULLETIN 



4 ItH 



Published by the Neiu York Zoological SoSii!^. 



Vol. XVIII. 



NOVEMBER, 1913 



Number G 



THE rOWER OF THE SHARK-SUCKERS DISK 



Bl/ C. H. TOWNSEND. 



THE shark suckfrs or Remoras are fishes 

 well known for their habit of accompany- 

 ing' sharks, to which they cling by means 

 of a broad sucking disk which covers the entire 

 to)) of the head. They also attach themselves 

 to sea turtles, porpoises, large oceanic fishes 

 and even to the hulls of vessels. 



The largest shark sucker in the New York 

 Aquarium, (Echfiieis naiicratcs) is thirtv-two 

 and one-half inches long and has a sucking disk 

 seven inches long and three inches wide. The 

 head disk in such fishes is capable of taking a 

 marvelously tight hold of any smooth surface 

 it may attach to. 



While the writer was naturalist of the United 

 States Fisheries Steamer Albatross, we caught 

 many of these fishes, nearly all sharks hauled 

 on board being accompanied by one or more of 

 them. When such fishes were thrown into tubs 

 or pails of sea-water to await further examina- 

 tion, they at once took hold of the vessel and 

 could not be detached without the use of consid- 

 erable force. On board the Albatross I have 

 frequently taken a shark sucker by the tail and 

 lifted it with the bucket containing more or less 

 water, without making the fish loosen its hold. 



In order to test the power of attachment of 

 which the cephalic disk is capable, I recently 

 made experiments with shark suckers in the 

 Aquarium. 



The first specimen tested was two feet long. 

 A stout cord was tied around the tail and the 

 fish dro]ii)ed into a four-gallon galvanized pail 

 half filled with water. Lifting steadily on the 

 cord, I raised the pail and water without the 

 fish's grip giving way an inch. The pail and 

 water weighed twenty-one jiounds. 



The second specimen was twenty-six and one- 

 half inches long, and its cephalic disk five and 

 one-half inches. Lifting the fish by the tail, 

 the bucket with more water added, was raised 

 entirely clear of the ground, some of the water 

 spilling out. The bucket and remaining water 

 weighed twenty-four and one-quarter pounds. 

 Had a deeper bucket been used, the fish might 

 have lifted a greater weight, but the specimens 

 were valuable and severer tests were not at- 

 tempted. 



Mr. Mowbray of the Aquarium staff, suggests 

 that with such weights of water as we used in 

 our tests, the fish cannot relax the grasp of its 

 disk, and that greater weights would only tear 

 the fish apart at some ))oint. He once mutilated 

 and killed a shark-sucker in trying to forcibly 

 detach it from the bottom of a boat into which 

 it had been thrown. 



In several of the published descriptions of 

 the shark-sucker, reference is made to the ac- 

 count given b}' Columbus, who said it was used 

 bv natives for the capture of turtles and fishes. 

 With a line attached to its tail, it was liberated 

 from the canoe near the turtle to be captured. 

 Its hold was always tight enough to permit 

 of the sea turtle being hauled within reach. 



The account seems to be straightforward 

 enough, but considerable research has failed to 

 bring to light any corroboration of it, as con- 

 cerns American waters. So far as can be as- 

 certained the natives of Cuba make no use of 

 shark-suckers in fishing and have no knowledge 

 of its use in the past. 



But we do not have to de))end wholly on the 

 narrative of Columbus. In the Proceedings of 

 the London Zoological Societv for 1884, Mr. 



