Morski pas, trouglasto peraje ajkula uliva strah kod svih onih koji ga ugledaju na morskoj površini. Ajkule su odlični i brzi plivači, odličnih čula. Savršeni su lovci i nazivaju ih "mašinama za ubijanje."
Međutim, nisu one sve opasne. U najagresivnije spadaju mako, tigar ajkule i "čekićare" - koje su dobile ime po specifičnom obliku glave. Potencijalno mogu biti opasne i sive ajkule. Najpoznatije među ljudožderima su velike bele ajkule, koje su dobile ime po izuzetnoj veličini koju pojedini primerci dostižu
Sinonimi: six-gilled shark | Hexanchus griseus
Large primitive shark widely distributed in warm seas; SYN. six-gilled shark, Hexanchus griseus.
Primitive sharks; Also called: family Hexanchidae.
ETYM Of uncertain origin; perhaps through Old Fren. from carcharus a kind of dogfish, Greek karcharias, so called from its sharp teeth, from karcharos having sharp or jagged teeth; or perhaps named from its rapacity; cf. Corn. scarceas.
Any of numerous elongate mostly marine carnivorous fishes with heterocercal caudal fins and tough skin covered with small toothlike scales.
Any member of various orders of cartilaginous fishes (class Chondrichthyes), found throughout the oceans of the world. There are about 400 known species of shark. They have tough, usually gray, skin covered in denticles (small toothlike scales). A shark’s streamlined body has side pectoral fins, a high dorsal fin, and a forked tail with a large upper lobe. Five open gill slits are visible on each side of the generally pointed head. Most sharks are fish-eaters, and a few will attack humans. They range from several feet in length to the great white shark Carcharodon carcharias, 9 m/30 ft long, and the harmless plankton-feeding whale shark Rhincodon typus, over 15 m/50 ft in length.
Relatively few attacks on humans lead to fatalities, and research suggests that the attacking sharks are not searching for food, but attempting to repel perceived rivals from their territory.
Game fishing for “sport”, the eradication of sharks in swimming and recreation areas, and their industrial exploitation as a source of leather, oil, and protein have reduced their numbers. Some species, such as the great white shark, the tiger shark, and the hammerhead, are now endangered and their killing has been banned in US waters since July 1991. Other species will be protected by catch quotas.