Riddle: What has eight arms and two tentacles, lives in the deep ocean and is bigger than a giant squid? Answer: The Colossal Squid.

The Colossal Squid, Mesonychoteuthis hamiltoni, is thought to be the largest of the squid species in weight, even exceeding that of the famous Giant Squid, Architeuthis dux. This species was first described in 1925 when two arms of the creatures were recovered from the stomach of a sperm whale. After that very little was learned about the Colossal Squid for many years as only a few incomplete or damaged specimens were found.

In 2003 the colossal squid again got the attention of the popular press when a nearly intact specimen was brought up from deep Antarctic waters at a depth of over 6,000 feet. Just three years later another specimen, a female 26 feet in length and weighing 1095 pounds, was captured accidently by a fishing boat near New Zealand in Antarctic waters. This particular animal is thought to be the largest invertebrate animal ever found.

Scientists have reasons to believe that even larger colossal squid might still be lurking in the deep than the one captured by the New Zealand fishermen. "When we first examined colossal squid specimens, we predicted that they might grow to 1,100 pounds (500 kilograms)," said Chris Paulin of New Zealand's national museum. "This specimen shows that they can grow larger still, to maybe 1,600 pounds (750 kilograms)."

One clue to suggest that there may be bigger Colossal Squids out there is the size of the beak of the New Zealand specimen. While it is large, 40 millimeters (1.57 inches), even larger ones measuring 49 millimeters (1.92 inches) have been found in the stomach of sperm whales which feed on the squid.

Colossal Squid vs. Giant Squid

The Colossal Squid and the Giant Squid are similar in many ways. Both creatures have a cone-shaped mantle topped by fins at one end. Protruding from the bottom of the mantle is a funnel through which the creatures can force water to propel itself about. Also below the bottom of the mantle is the head which houses the creature's huge eyes and mouth/beak. Radiating out from around the beak are eight arms and two tentacles. The tentacles are longer than the arms and widen at the very end in a "club" shape. The tentacles are used to capture fish and bring them to the animal's beak where they can be consumed.

Compared to the Giant Squid the Colossal Squid seems to have a larger, heavier body with shorter arms and tentacles. The club at the end of its tentacles just doesn't have the suckers with tiny teeth like the Giant Squid, but 25 swiveling hooks that allow it to catch and hold very large fish. The eight arms of the Colossal Squid also carry fixed hooks which the Giant Squid does not have.

Both the Colossal Squid and the Giant Squid live in deep water, perhaps as much as 3,300 feet (1000 meters) or more beneath the surface, where there is very little light. To help them hunt their prey in the darkness at that depth they have extremely large eyes. The 2005 New Zealand specimen's eye sockets were roughly the size of a small beach ball at 11 inches (28 centimeters) across with lens the size and shape of an orange. To help conceal themselves from other creatures at these depths, these big squid are colored a deep shade of pink. When sunlight passes through water the red wavelengths are more quickly absorbed, anything near the bottom of the sea with a red or pink color, including the Colossal Squid, will be virtually invisible. This assists the squid as it hunts or hides from its main predator, the sperm whale.

Both of these large squids are major sources of food for the sperm whale. Scientists estimate the Colossal Squid may make up 77% of the diet by weight of Antarctic sperm whales feeding in the Southern Ocean. Even so, neither of these large squid are an easy meals. Scientists have found the skin of sperm whales scarred with sucker and hook marks from squid that clung to the whale's body in a desperate bid to avoid being consumed.

Abyssal Gigantisum

Large squids exhibit deep-sea gigantism, also known as abyssal gigantism. Many animals living in the depths grow to much larger sizes than their counterparts dwelling near the surface. Some examples of these are the Japanese spider crab which can have a leg span 13 feet wide and a body 15 inches across; the giant isopod, a crustacean related to the shrimp that can grow up to 15 inches long, and the whale shark which get as lengthy as 40 feet. Scientists have several theories about why these creatures get so big at the bottom of the sea. One is that their food supplies are scarce and fragmented over large areas so the animals need to be huge so they can range over great distances to feed. Another is that the extreme cold of the depths is better tolerated by large animals because they have much larger interval volume compared to their surface area. With less surface area to leak heat they can conserve their warmth better.

The specimen of the Colossal Squid captured in 2005, though it was large, wasn't very old. Examination of the creature's statoliths, or equilibrium organ, which has rings (much like a tree's growth rings), indicates it had been born only 18 months earlier. The animal also appeared to be a less aggressive creature than the scientists had first expected. Squid expert Steve O'Shea, from the Auckland University of Technology, was surprised to see the squid was an "enormous blob."

Monster Blob

"We are looking at something verging on the incredibly bizarre," Dr O'Shea said. "As she gets bigger she is reduced to little more than a giant gelatinous blob." This growth probably changed the creature's activity level. "Her shape was likely to have affected her behavior and ability to hunt," added O'Shea. "I can't imagine her jetting herself around in the water at any great speed, and she was too gelatinous to have been a fighting machine."

This isn't to say that the creature was harmless. "I still don't want to be in the water with it," observed O'Shea. He also notes it was probably a more aggressive hunter when it was younger. "It's not sitting down there sipping on cups of tea or anything like that," he notes. "It's got this arsenal of beaks and hooks which at some stage in its life-cycle it would have used."

Copyright Lee Krystek 2008. All Rights Reserved.