Mackerel sharks
Characteristic features:

Key adapted from Compagno, 2001.1

Lamnidae species
    1. Origin of first dorsal fin level with or slightly forward of pectoral-fin rear tips (Fig. 1a); anal-fin origin behind second dorsal-fin base (Fig. 2a); upper teeth with triangular and strongly serrated cusps (Fig. 3a) Carcharodon carcharias
    2. Origin of first dorsal fin level behind pectoral-fin rear tips (Fig. 1b); anal-fin origin below midbase or insertion of second dorsal fin (Fig. 2b,c); upper teeth with narrow and smooth-edged cusps (Fig. 3b,c) 2
    1. Snout acutely pointed, it’s under surface white (Fig. 4a); pectoral fins much shorter than head, tips narrowly to acutely pointed (Fig. 5a); anal-fin origin about level with midbase of second dorsal fin (Fig. 2b); cusps of upper and lower anterior teeth recurved at bases but with tips reversed and curving outwards Isurus oxyrinchus
    2. Snout narrowly to bluntly pointed, its undersurface dusky (Fig. 4b); pectoral fins about as long as head, more broadly tipped (Fig. 5b); anal-fin origin about level with second dorsal-fin insertion (Fig. 2c); cusps of upper and lower anterior teeth straighter, with tips not reversed Isurus paucus
Similar families:

Whaler sharks

Carcharhinidae feature image

Carcharhinidae differ in having well-developed nictitating lower eyelids (vs. no nictitating lower eyelids); a strongly asymmetrical caudal fin with the upper lobe longer than the lower (vs. caudal fin lunate and near symmetrical, upper and lower lobes of similar length); a caudal peduncle not greatly flattened dorsoventrally (vs. caudal peduncle strongly flattened dorsoventrally and expanded laterally); a longitudinal keel on caudal peduncle weak (Prionace glauca) or absent (vs. prominent, extending well out from peduncle) and intestinal valve scroll type (vs. ring type).

  1. Carpenter K, Niem V, Compagno L. Lamnidae. In: FAO Species Identification Guide for Fishery Purposes. The Living Marine Resources of the Western Central Pacific. Volume 2. Cephalopods, Crustaceans, Holothurians and Sharks. Vol 2. Rome: FAO Library; 2001:1274-1278.