Colossal Squid Revealed

Strange facts about the ocean’s most mysterious creature

Armored Arms

Each of the squid's eight arms has 20 suckers near the beak, 16 hooks farther down the arm, and about 150 suckers near the tip. The hooks on the arms hold and immobilize the prey while the squid chows down.Mesonychoteuthis hamiltoni Robson/ Museum of New Zealand Te Papa Tongarewa

Night Vision

At almost 10 inches in diameter, these are the largest eyes ever recorded. The huge pupils take in 144 times as much light as a human's. "Vision is obviously an important sense, since so much investment has been made in the eyes and the optic lobes," says Eric Warrant, an invertebrate-vision specialist at the University of Lund in Sweden.Mesonychoteuthis hamiltoni Robson/ Museum of New Zealand Te Papa Tongarewa

Killer Tentacles

One common hunting strategy among smaller squid (it's thought that all squid exhibit similar behavior) is to strike prey first with their tentacles. The 10-foot-long tentacles of the colossal squid have hooks that swivel, grabbing hold of prey. When this squid was caught, it was eating a 6.5-foot-long Patagonian toothfish.Mesonychoteuthis hamiltoni Robson/ Museum of New Zealand Te Papa Tongarewa

Vicious Beak

The squid fillets fish with its beak by eating the flesh up one side and down the other. "Much worse for the fish is if the squid starts eating at the tail end," says Auckland University of Technology Ph.D candidate Kathrin Bolstad.Mesonychoteuthis hamiltoni Robson/ Museum of New Zealand Te Papa Tongarewa

Clues to Their Size

From beak remnants, researchers have determined that colossal squid account for 77 percent of the sperm whale's Antarctic diet. "The biggest beaks recorded are still larger than the ones we've had in our specimens, so we know the animal must get bigger still," Bolstad says.Mesonychoteuthis hamiltoni Robson/ Museum of New Zealand Te Papa Tongarewa

Head

The squid has a doughnut-shaped brain; the esophagus passes straight through the center.NOAA

Hearts

This squid has three hearts: one major central one and two smaller pumping stations at each gill.Mesonychoteuthis hamiltoni Robson/ Museum of New Zealand Te Papa Tongarewa

Fins

Large, powerful fins are about five feet in diameter and make the squid a fast and very agile predator.Mesonychoteuthis hamiltoni Robson/ Museum of New Zealand Te Papa Tongarewa

Mantle

The mantle, which helps the squid swim, is fused to the head in three places and is heavily muscled. Instant Expert: Launch Your Quick and Easy Primer on Just About Everything at popsci.com/instantexpert.fish.govt.nz