• FISHES OF THE GULF OF MAINE 349 



THE REMORAS. FAMILY ECHENEIDIDiE 



The several remoras are easily distinguished from all other fishes by the fact 

 that the spiny part of the dorsal fin is modified into a flat oval sucking plate com- 

 posed of a double series of cartilaginous crossplates with serrated free edges situated 

 on the top of the head and neck. All remoras, too, are slender of form with the 

 lower jaw projecting far beyond the upper. Their large mouths are armed with many 

 small pointed teeth, their soft dorsal and anal fins similar in form and size and one 

 above the other, and their pectorals set high up on the sides. The lower surface 

 of the head is convex, the upper flat — just the reverse of the usual rule — with the 

 lower surface of the body as deeply colored as the upper, the back often being mis- 

 taken for the belly. The members of this family all attach themselves to other 

 fishes or to sea turtles by their sucking disk, usually clinging to the sides of the hosts 

 but often within the mouth or gill cavities of the larger sharks and giant rays.' 

 Thus they are carried about, and they feed on the scraps of the meals of their trans- 

 porters. All remoras are tropical, and they appear only as strays in boreal seas, 

 usually fast to sharks or swordfish. 



We follow Sumner, Osborne, and Cole (1913, p. 766) in uniting under one 

 species the shark sucker (naucrates) , with more than 21 plates but a sucking disk less 

 than one-f oiu-th as long as the body, and the pilot sucker {naucrateoides) , with only 

 20 or 21 plates but longer sucker — fishes that are otherwise indistinguishable, one 

 from the other. 



Fig. 172.— Shark sucker (Echeneis naucrates) 



KEY TO GULF OF MAINE REMORAS 



1. Pectoral fins pointed; ventrals attached to the belly for less than one-third their length 



Shark sucker, p. 349 



Pectorals rounded; ventrals attached to the belly for more than half their length 2 



2. Dorsal fin of 29 rays or more; at most 16 plates in the sucker Swordfish sucker, p. 350 



Dorsal fin of only about 23 rays; about 18 plates in the sucker Remora, p. 351 



133. Shark sucker (Echeneis naucrates Linnfeus) 

 Pilot sucker; White-tailed sucker 

 Jordan and Evermann {Echeneis naucrates and E. naucrateoides), 1896-1900, pp. 2269-2270. 



Description. — The most diagnostic characters are mentioned above. This 

 is a very slim fish, 11 or 12 times as long as deep, nearly round in section, and 

 tapering to a very slender caudal peduncle. The sucking disk, extending from 

 close behind the tip of the snout as far back over the nape of the neck as the mid- 

 dle of the pectoral fin, is about as broad as the head, flat, oval, and with very con- 

 spicuous transverse plates 20 or more in number. This disk is the most notice- 



' Gudger (Natural History, Vol. XXII, No. 3, May- June, 1922, p. 243-249) gives an interesting account of this habit. 



