page_title: Bigeye sand tiger
section_title: Description
hierarchical_section_title: Bigeye sand tiger / Description
caption_attribution_description: Odontaspis noronhai
context_page_description: The bigeye sand tiger is an extremely rare species of mackerel shark in the family Odontaspididae, with a possible worldwide distribution. A large, bulky species reaching at least 3.6 m in length, the bigeye sand tiger has a long bulbous snout, large orange eyes without nictitating membranes, and a capacious mouth with the narrow teeth prominently exposed. It can be distinguished from the similar smalltooth sand tiger by its teeth, which have only one lateral cusplet on each side, and by its uniformly dark brown color.
  Inhabiting continental margins and oceanic waters at depths of 60–1,000 m, the bigeye sand tiger may make vertical and horizontal migratory movements. It feeds on bony fishes and squid, and its sizable eyes and dark coloration suggest that it may spend most of its time in the mesopelagic zone. Reproduction is probably viviparous with oophagous embryos like in other mackerel shark species. This shark is caught incidentally by commercial fisheries, though so infrequently.
context_section_description: With its heavyset body, conical bulbous snout, and large mouth filled with protruding teeth, the bigeye sand tiger looks much like the better-known sand tiger shark. The large eyes lack nictitating membranes, and behind them are small spiracles. The corner of the mouth extends to behind the level of the eyes, and the jaws are highly protrusible. There are 34–43 upper and 37–46 lower tooth rows; these include zero to two rows of small teeth at the upper symphysis (jaw midpoint) and two to four more rows at the lower symphysis. In each half of the upper jaw, the teeth in the first and second rows are large, those in the third and sometimes fourth rows are small, and those in the rows after are large again. Each tooth has a narrow, awl-like central cusp flanked by one smaller cusplet on each side; this contrasts with the smalltooth sand tiger, which has two or three lateral cusplets on each side. There are five pairs of gill slits.
  The pectoral fins are medium-sized and broad with rounded tips. The large first dorsal fin has a rounded apex and is positioned closer to the pectoral than the pelvic fins. The second dorsal fin is about half the size of the first and originates over the rear tips of the pelvic fins. The pelvic fins are almost as large as the first dorsal fin. The anal fin is smaller than the second dorsal fin and positioned behind it. The caudal peduncle has a crescent-shaped notch at the dorsal origin of the caudal fin. The lower lobe of the caudal fin is short but distinct, while the upper lobe is long and has a deep notch in the trailing margin near the tip. The skin is covered by overlapping dermal denticles, each with three horizontal ridges leading to marginal teeth. This species is plain dark reddish brown to chocolate brown, sometimes with black trailing margins on the fins or a white-tipped first dorsal fin. The eyes are dark orange with vertically oval, green-tinted pupils. There are several black patches inside the mouth, such as around the jaws, on the floor of the mouth, and on the gill arches. The largest male and female specimens measured 3.6 and 3.3 m (12 and 11 ft) long respectively.
caption: The teeth differ in shape in the bigeye sand tiger and in other, similar species.
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