Which aggressive squid is an infamous cannibal?


By Earl Filskov


First discovered in the Pacific Ocean off the coast of Chile in 1835 by French naturalist Alcide d’Orbigny, the Humboldt squid (Dosidicus gigas) has developed a nasty reputation. In addition to cannibalizing other Humboldt squids, it has been reported to attack humans as well.

Considered large by cephalopod standards, the Humboldt squid can develop a mantle length (its body) up to 9 feet and weigh 100 pounds. Pumping water through its mantle in an aquatic version of jet propulsion, it is swift, attacking prey or escaping predators at speeds up to 15 miles per hour by blowing jets of water out of its two siphons.

During daylight hours, the Humboldt dives to depths of 2,300 feet or more, reaching the oxygen minimum zone (OMZ). It is still a mystery how they breathe or survive in the OMZ due to never being observed at this depth. At night they ascend the water column, reaching more oxygen-rich depths (160 to 230 feet) where they feed on plankton and lantern fish.

The Humboldt squid’s taste for lantern fish is used against it by fishermen. Shining lights into the water at night illuminates the plankton drawing the Humboldt closer to the surface for easy catching. The squid has tricks of its own and is known to feed on the fish and and other animals caught on the fishermen’s lines before they can be reeled into boat. Tuna, sharks, and other Humboldt are the most common animals stripped right off the hook.

They attack their prey quickly by extending its two tentacles, which are covered with suckers, out from its eight arms to grab the prey. It then carries the prey into its arms where the prey is moved towards its mouth where it tears the flesh from the bones.

“It’s like they are sucking the animal right in,” biologist William Gilly said of the speed with which squid demolish their prey. “But they leave the bone. I don’t believe they have the jaw muscles to crush through it. Fishermen have been bitten by the squid, but I have never heard of a serious accident.”

Despite being cannibals, they are known to be very social animals, traveling in the shoals in groups as large as 1,000 or more squid. They travel from the coast of Peru up to the southern California area by way of vertical migration (meaning they dive deep during the day and surface at night). Beginning with the extraordinarily large El Nino weather patterns that occurred in 1997-1998 the Humboldt was first spotted in Monterey Bay off the coast of Northern California. They appeared again with a smaller El Nino event in 2002 and have been regular visitors since.

Starting in 2004 there have been several sightings of Humboldt squid as far north as Alaska causing concern among scientists that a change in their habitat may be driving them north to look for food. Some scientists have suggested that warming trends are driving them north at certain times or loss of prey at their feeding depths in the Pacific Ocean.

With a life span of only one year (some larger members can live up to two years), the Humboldt reproduces in monumental numbers. Females produce an egg mass containing between 600,000 to 2 million eggs and will do this three to 20 times in her short life span.

Humboldt squids have three hearts, blue blood and the size of their brain suggests they are very intelligent. Believed to communicate by body movements and flashing lights at each other by way of their photospores. Photospores are light-producing organs that most cephalopods possess on their bodies as a defensive mechanism. The Humboldt squid is believed to be one of the most intelligent invertebrates.

Attacks on humans have been documented, yet attacks only happen when they feel threatened. Unfortunately for deep-water divers, camera lights are believed to be one of the perceived threats that have caused some of the attacks. No one has ever been seriously hurt or killed by a Humboldt squid, but many cameras have suffered a dire fate.
“Humboldt or Jumbo Squid.” Smithsonian National Zoological Park. Web Accessed Friday, March 6, 2015.

Cosgrove, James A. & Sendall, Kelly A. “First Records of Dosidicus gigas, the Humboldt Squid in the Temperate North-eastern Pacific.” The Cephalopod Page. Web Accessed Friday, March 06, 2015.


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