Body elongate, head flattened, and lower jaw projecting past upper jaw; scales small, cycloid; dorsal and anal fins lacking spines, each with about 18-45 soft rays; swim bladder absent; branchiostegal rays 8-11; 26-41 vertebrae; sucking disc on head (developed from a transformed spinous dorsal fin, the spines of which are split to form 10-28 transverse movable lamina inside a fleshy margin). The remora presses the disc against other fishes and creates a partial vacuum by operating the movable disc ridges like the slats in a Venetian blind, thereby causing the sucking action that permits it to obtain rides on larger animals. Remoras are found on sharks, bony fishes, sea turtles, and marine mammals; some species show considerable host specificity. A fully formed disc is present in specimens as small as 27 mm. Maximum length about 1.0 m, attained in Echeneis naucrates. The smallest species is 17 cm.
See note on sister-group relationships above under family Coryphaenidae. A Lower Oligocene fossil was described by N. Micklich in 1998.
Four genera, Echeneis, Phtheirichthys, Remora, and Remorina, with eight widespread species (Smith-Vaniz et al., 1999; O'Toole, 2002; Collette, 2003c).
Family CARANGIDAE (364)—jacks and pompanos. Marine (rarely brackish); Atlantic, Indian, and Pacific.
Body generally compressed (but ranging from very deep to fusiform); only small cycloid scales in most species, ctenoid in a few (some scales on the lateral line are modified into spiny scutes in many species), naked areas variously developed; up to nine detached finlets sometimes present behind dorsal and anal fins (counts for these rays are included in following ray counts); two dorsal fins in large juveniles and adults, the first with 4-8 spines (which in a few species are very short and lack a continuous membrane) and the second with one spine and 17-44 soft rays; usually three anal spines with the first two (rarely only one) detached from the rest of the anal fin and usually 15-39 soft rays; caudal fin widely forked; caudal peduncle slender; vertebrae 24-27 (usually 24).
Carangids are extremely variable in body shape, ranging from the shallow-bodied Decapterus and Elagatis to the extremely thin and deep-bodied Selene. The family contains some very important food species. The juveniles of some species extend into estuaries.
Two carangid species lack the pelvic fins, the surf inhabiting Parona signata from off southern Brazil and Argentina, and the epipelagic Parastromateus niger (in above figure), from the Indo-West Pacific. The latter species, which has a small pelvic fin in juveniles under 9 cm, was placed in its own family, Apolectidae (Formionidae), in Nelson (1984); placement in Carangidae follows the 1984 study of W. F. Smith-Vaniz. Both species have a deep and extremely compressed body, but what the selective forces are that are causing an independent loss of the pelvic fins in the only percoids to lack these fins is unknown; their ecology and swimming behavior are very dissimilar. Paleocene-Eocene species of the genus Trachincaranx, which have the pelvic fins, may be relatively closely related to Parastromateus.
Some of the common names used for carangids are amberjacks, jacks, moonfishes, pilotfish, rudderfishes, pompanos, scads, and trevallies (singular trevally = crevally).
About 32 genera and 140 species (e.g., Smith-Vaniz et al., 1999; Smith-Vaniz, 2003). Four subfamilies are provisionally recognized following the major 1984 study of W. F. Smith-Vaniz (he ranked them as tribes). S. Gushiken published a phylogenetic study in 1988.
Trachinotinae—Two genera, Lichia and Trachinotus, with 21 species. Scomberoidinae—Three genera, Oligoplites, Parona, and Scomberoides, with 10 species.
Naucratinae—Five genera, Campogramma, Elagatis, Naucrates, Seriola, and Seriolina, with 13 species.
Caranginae—only subfamily with scutes present. Twenty-two genera (e.g., Alectis, Atropus, Carangoides, Caranx, Chloroscombrus, Decapterus, Gnathanodon, Hemicaranx, Megalaspis, Parastromateus, Pseudocaranx, Selar, Selene, Trachurus, and Uraspis) with about 96 species (the status of Citula is uncertain).
Was this article helpful?