Humboldt squid

The Humboldt squid (Dosidicus gigas), also known as jumbo squid, jumbo flying squid, pota, or diablo rojo (red devil), is a large, predatory squid living in the waters of the Humboldt Current in the eastern Pacific Ocean. It is the only species of the genus Dosidicus of the subfamily Ommastrephinae, family Ommastrephidae. Humboldt squid typically reach a mantle length of 1.5 m (4 ft 11 in). They have a reputation for aggression towards humans, though this behavior may possibly only be manifested during feeding times. Like other members of the subfamily Ommastrephinae, they possess bioluminescent photophores and are capable of quickly changing body coloration (metachrosis). They notably rapidly flash red and white while hunting, earning them the name diablo rojo (Spanish for 'red devil') among fishermen. These chromatophores (which belong to more than one set and are of different sizes) may rapidly cycle through colors other than red and white, flashing too quickly for the human eye to see the transitions. They have a relatively short lifespan of just 1-2 years. They are most commonly found at depths of 200 to 700 m (660 to 2,300 ft), from Tierra del Fuego to California. This species is spreading north into the waters of Oregon, Washington, British Columbia, and Alaska. They are fished commercially, predominantly in Mexico and Peru. The genus contains bioluminescent species. Some squid may grow to 2.5 m (8 ft 2 in) in mantle length and weigh up to 50 kg (100 lb). Generally, the mantle (or body) constitutes about 40% of the animal's mass, the fins (or wings) about 12%, the arms and tentacles about 14%, the outer skin about 3%, the head (including eyes and beak) about 5%, with the balance (26%) made up of the inner organs. Humboldt squid are carnivorous marine invertebrates that move in shoals of up to 1,200 individuals. They swim at speeds up to 24 km/h (15 mph; 13 kn) propelled by water ejected through a hyponome (siphon) and by two triangular fins. Their tentacles bear 100–200 suckers, each lined with razor-sharp teeth, with which they grasp prey and drag it towards a large, sharp beak. Although Humboldt squid have a reputation of being aggressive towards humans, some disagreement exists on this subject. Research suggests these squid are only aggressive while feeding; at other times, they are quite passive. Their behavior while feeding often extends to cannibalism and they have been seen to readily attack injured or vulnerable squid of their own shoal. A quarter of squid stomachs analyzed contained remains of other squid. This behavior may account for a large proportion of their rapid growth. Some scientists claim the only reports of aggression towards humans have occurred when reflective diving gear or flashing lights have been present as a provocation. Roger Uzun, a veteran scuba diver and amateur underwater videographer who swam with a swarm of the animals for about 20 minutes, said they seemed to be more curious than aggressive. In circumstances where these animals are not feeding or being hunted, they exhibit curious and intelligent behavior.. Electronic tagging has shown Humboldt squid undergo diel vertical migrations, which bring them closer to the surface from dusk to dawn. Humboldt squid are thought to have a lifespan of only about a year, although larger individuals may survive up to 2 years.