The orders, families and genera of "Mackerel sharks"

These are large sharks with very prominent jaws and teeth. Yet despite their appearance, they are harmless. There are 4 species belonging to 2 genera. Their body is cylindrical, slightly compressed and moderately stout. Sand tigers possess a very pointed snout, with small eyes. Both dorsal fins are of similar size, as is the anal fin. The origin of the first dorsal fin is over or behind the position of the pectoral fins. Sand tigers are found in tropical to cold, temperate waters, both inshore and deeper waters, even on the upper continental slopes down to about 1500 m . Sand tiger sharks are known to gulp air to increase their buoyancy. They feed primarily on fishes. It is known, for at least one species, Caracharias taurus, that they hunt in groups. They show an ovoviviparous style of reproduction (aplacental viviparity) with a unique form of embryological phagism, the so-called intra-uterine cannibalism where older embryos feed on siblings of earlier stages.

The family of mackerel sharks consists of 3 genera with 5 species. All of them show several adaptations for fast swimming. This family includes species such as the white and mako shark. All mackerel sharks have a very pointed snout, very dark eyes, relatively large pectoral fins, lunate tails and keels on their peduncles. As other members of the same order this family possesses specially adapted blood circulatory systems that enables these sharks to keep a higher body temperature and therefore higher level of activity. Mackerel sharks prefer cooler waters over the continental shelves and outer slopes and are normally not abundant in tropical waters. These are very active and powerful sharks.

This family consists of one species, the basking shark, Cetorhinus maximus, of unmistakable appearance. This huge shark grows to 10 m and has enormous gill slits that nearly encircle their huge mouth and head. Basking sharks have a small and very pointed snout. The first dorsal fin is large, high and erect. The caudal fin is lunate shaped. Basking sharks belong to the very few plankton feeders of sharks. They swim with an open mouth through the water but do not suck the water in, as it is typical for the whale sharks. Basking sharks shed their gill rakers once a year and move then to deeper waters, seemingly synchronised with the plankton densities in temperate waters. Many questions remain in regards to their behavioural biology. Basking sharks are normally found below the surface and can move in aggregations. Such a scenario might have led to many of the 'sea serpent' stories. Basking sharks show a very wide distribution in temperate waters over continental shelves of both the northern and southern hemispheres.

This family was discovered in 1976 when the first specimen of the megamouth, Megachasma pelagios. was found in Hawaii. To date, no more than 10 animals have been found (9 males, 1 female). They are big sharks with a cylindrical trunk, very round head, huge, terminal mouth with a white upper lip. They have large pectoral fins and a relatively large first dorsal fin (compared to the second one). The biology of this species is poorly understood. The ninth specimen was the first one that has been found in the Atlantic. It is assumed that megamouth is a deepwater species with a sluggish lifestyle. They seem to prefer plankton but other invertebrates and even small fishes have to be considered as potential food.

Only one species represents this family, the goblin shark, Mistukurina owstoni. It is a very unique, unmistakable shark, with a very long head that is as long or slightly shorter than the trunk. The snout is greatly elongated, flattened and blade-like. The upper lobe of the caudal fin is also elongated. The pectoral fins are very small. The body is very soft and flabby. The body has a pinkish-white coloration, the fins are bluish. This uncommon, bottom-dwelling species inhabits the continental shelves and upper slopes down to at least 500 m . The biology of the goblin sharks is poorly understood but the blade-like snout shows resemblance to paddlefishes and it is assumed that goblin sharks may use them as a forward-projecting prey detector. They feed on fishes, squids and shrimps. Their form of reproduction is still questioned.

A family with only one species, the crocodile shark, Pseudocarcharias kamoharai, is a very small species with very big eyes. Crocodile sharks do not possess nicitating membranes, have well developed gill slits and a long, spindle-shaped body. They have two spineless dorsal fins and weak keels on the peduncle with a precaudal pit in front of the caudal fin. The pectoral and dorsal fins are small. Crocodile sharks are abundant in epipelagic and possibly mesopelagic waters down to at least 300 m depth. The biology is not well known yet but their big eyes suggests nocturnal or deepwater activity, and possibly a diel pattern of movement toward the surface at night. It is assumed that crocodile sharks feed on small fishes. They show an ovoviviparous style of reproduction (aplacental viviparity) with an intra-uterine cannibalism.

This is an unmistakable family as all species possess huge tails as long as the trunks. This large tail is used to herd schooling fish and then stun them with a whip of their tails. Their body is cylindrical and moderately stout. Their snout is pointed. Large pectoral fins are present. The first dorsal fin is large and erect, while the second one is minute. The pelvic fins are nearly as large as the first dorsal fin. 3 species are recognised with a circumglobal distribution in tropical and temperate waters. All species are large and strong swimmers. They possess an oviviviparous style of reproduction (aplacental viviparity) with intra-uterine cannibalism.