Colossal squid characteristics, habitat, feeding, behavior

Alexander Pearson
Colossal squid characteristics, habitat, feeding, behavior

The colossal squid (Mesonychoteuthis hamiltoni) is a mollusk that belongs to the Cranchiidae family. It is a large animal, which can have a total length of up to four meters and a maximum weight of 750 kilograms.

The body of this cephalopod is reddish, with a white lower area. This is divided into three parts: the head, an area of ​​tentacles and arms and finally the mantle. Two huge eyes stand out on the head, which have light-emitting organs, known as photophores..

Colossal squid. By © Citron, CC BY 3.0,

This species, like all squid, has eight arms and two tentacles. These are located around the mouth opening. Both structures differ in various aspects. First, the arms are up to 1.15 meters, have suction cups and non-rotating hooks. As for the tentacles, they are approximately 2.1 meters long and have between 22 and 25 hooks that can rotate.

The two gripping organs help to hold the prey. However, the male uses his arms to support the female while they copulate..

Regarding the distribution, the Mesonychoteuthis hamiltoni inhabits the Southern Ocean, occupying depths of more than one kilometer.

Article index

  • 1 Features
    • 1.1 Morphology
    • 1.2 Size
    • 1.3 Polar and abyssal gigantism
    • 1.4 Vision
    • 1.5 Bioluminescence
    • 1.6 Gills
    • 1.7 Heart
    • 1.8 Gladius
  • 2 Taxonomy
  • 3 Habitat and distribution
  • 4 Food
    • 4.1 Hunting method
    • 4.2 digestive system
    • 4.3 Predators
  • 5 Playback
  • 6 Conservation status
  • 7 Behavior
  • 8 References 



The mantle or body of the Mesonychoteuthis hamiltoni, it can be up to 2.5 meters long. In relation to the mantle, it is made up of skin and muscles. At the top is the tail fin. This is used by the colossal squid to move, allowing it to change the direction of the swim.

In the ventral area it has an opening, known as a siphon. This funnel has a muscular structure, which is involved in respiration, movement and the discharge of waste.

Following the body, joined at the nape, is the head. In this are the eyes and the mouth opening. Around this structure there are eight arms, which have numerous suction cups throughout..

In addition, it has two tentacles at the end of which are large spikes. Also, it has 25 rotating hooks, organized in two rows in the terminal part of the tentacles. As for the fins, located in the terminal area of ​​the body, they are flexible and are used to propel the swim and to stabilize the animal.

Regarding the coloration, the dorsal area is brick red, with small black spots and light areas. Contrasting with these tones, the belly and the lower region of the tentacles and arms is white..


Comparison of the size of a colossal squid and a human. Source: © Citron

The colossal squid is the largest invertebrate currently living on the planet. Its size varies between 12 and 14 meters in length. The mantle measures 2 to 4 meters.

In terms of weight, the vast majority of species weigh around 500 kilograms. However, there are animals that could have a body mass of up to 750 kilograms.

Polar and abyssal gigantism

Scientists point out that some of the organisms in the polar areas could reach very large sizes. Thus, polar gigantism could be the explanation for the understanding of ecological theories and the principles that support the evolution of the colossal squid's body size..

On the other hand, although not in a consensual way, several experts hypothesize that polar gigantism could be related to abyssal gigantism. In this, the increase in the size of invertebrates and other animals is associated with their life in deep waters..

Regarding this approach, the M. hamiltoni It exhibits the largest eyes ever documented in the animal kingdom. These organs can have a diameter of up to 30 centimeters, with a pupil of 9 centimeters. In relation to the beak, it is the largest among all live squid.


As we have mentioned, the Mesonychoteuthis hamiltoni he has large eyes. The researchers suggest that this may have given the species an evolutionary advantage. This could be associated with a greater ability to detect large predators, such as the sperm whale, instead of facilitating the identification of prey that are at long distances.

The visual range of this species has been extensively studied. The researchers propose that the huge eyes are capable of capturing the tiny light sources coming from the bioluminescent plankton. These are activated when the sperm whale dives down to hunt. Thus, the colossal squid has enough time to escape from its predator.


Mesonychoteuthis hamiltoni it has photophores. These are light-emitting organs that are elongated in shape and are located on the ventral surface of each eye. These structures are made up of specialized mitochondrial cells, known as photocytes..

In this cephalopod, the photocytes have particular characteristics. In this sense, they are made up of crystalloids, which have profiles that resemble needles. In addition, reflective platelets are not common and are related to a microtubular matrix, which gives the edges a comb-like appearance..

Photophores can be used in various ways, depending on the needs of the animal. Thus, it could be a deceptive technique, since when the colossal squid is illuminated, the other species may not take it into account as a threat. This allows it to get up close and hunt the prey.


The colossal squid has two large gills, which hang from the mantle. Each organ has 20 to 80 gill filaments. The breathing process begins when water enters the mantle through an opening near the head. Then it goes to the gills, where gas exchange occurs.

Colossal Squid (Mesonychoteuthis hamiltoni)


The Mesonychoteuthis hamiltoni it has three hearts: one systemic and two branchial. These pump deoxygenated blood to the gills, where it is oxygenated. Then, they send the pure blood to the systemic heart, which passes it to the different organs and systems of the body.

As for the blood, it has a blue coloration. This is because it contains a copper-based protein called hemocyanin. This compound is responsible for transporting oxygen.


The colossal squid has a kind of internal shell, known as a gladius. This structure is rigid and crosses the upper area of ​​the mantle, giving support to the animal. It is made up of chitin, a very resistant element that can look like a long piece of transparent plastic.


-Animal Kingdom.

-Subkingdom: Bilateria

-Infra-kingdom: Protostomy.

-Superfilum: Lophozoa.

-Phylum: Mollusca.

-Class: Cephalopoda.

-Subclass: Coleoidea.

-Superorder: Decabrachia.

-Order: Teuthida.

-Suborder: Oegopsina.

-Family: Cranchiidae.

-Subfamily: Taoniinae.

-Genus: Mesonychoteuthis.

-Species: Mesonychoteuthis hamiltoni.

Habitat and distribution

Colossus squid. Source: https: //

The colossal squid is widely distributed in the Southern Ocean. Thus, it extends from the north of Antarctica to the south of South Africa, the southern part of South America and the southern region of New Zealand. The range coincides with the Antarctic circumpolar current, although the young could be found north of the subtropical convergence.

The Mesonychoteuthis hamiltoni, lives in waters more than 1000 meters deep. However, its location in oceanic waters varies, depending on the stage of development in which the cephalopod is found..

Based on the depth where it is caught, experts point out that the range of the juvenile colossal squid is probably up to 1 kilometer, while that of the adult can reach up to 2.2 kilometers.

In terms of population density, the highest index occurs in the Sea of ​​Cooperation, in the Indian Ocean region of Antarctica. The lowest concentration is in the Ross Sea, south of New Zealand. This may be associated with the fact that one of its main predators, the Antarctic hake (Dissostichus mawsoni).


The colossal squid feeds on mesopelagic fish, such as some species of the families Paralepididae and Myctophidae. Also, eat sleeping shark (Somniosus microcephalus) and toothfish (Dissostichus eleginoides).

Their diet may include squid, including squid of the same species. In the case that these are small, locate and hunt them using bioluminescence.

Hunting method

Previously, this species used to be related to the group of fast and voracious predators. This could be associated with their large body size and long, strong arms and tentacles. However, currently different information is handled.

According to some research, experts point out that the Mesonychoteuthis hamiltoni it has a low metabolic rate. According to estimates, an adult weighing 500 kilograms needs to consume approximately 30 grams of food daily.

Therefore, specialists state that this species is a predator that lacks the ability to perform a high-speed predator-prey interaction. Because of this, it captures its prey using the ambush method..

To catch animals, due to its large size and low energy requirement, the colossal squid does not chase the fish. He waits patiently for him to be close and attacks him with the spikes of his arms..

Digestive system

The prey is captured and introduced by the beak, which cuts it into small pieces. Thus, it facilitates its passage through the thin esophagus, which connects the beak with the stomach. In relation to the stomach, it is a small sac where the digestive process begins.

Digestive enzymes secreted by the pancreas and the liver are involved in the degradation of organic compounds. The food mass is transferred from the stomach to the cecum, where digestion is complete and nutrients are absorbed..

As for the waste, it passes into a narrow tube called the intestine. Finally, all the residual material comes out through the anus.

In the following video you can see a specimen of this species near a boat:


Currently, the colossal squid has approximately 17 species of predators. These include penguins, fish, seabirds, and marine mammals. The largest of this group is the sperm whale, followed by the sleeping shark..

Specialists have found peaks of the Mesonychoteuthis hamiltoni in the stomach of toothfishDissostichus eleginoides). Likewise, some seabirds, such as the gray-headed albatro (Thalassarche chrysostoma) and black eyebrow (Thalassarche melanophrys), consume remains of this cephalopod.


The colossal squid is sexually mature and reproduces much later than the other species of its genus, which live in more northern areas. Thus, it can mate when it measures at least one meter and its weight is greater than 30 kilograms. Thus, it is one of the most fertile, among the group of polar cephalopods.

According to research, the adult male lacks hectocotyl. This organ, located at the end of one of the tentacles, is present in squid. Its function is to store and transfer sperm.

In place of this reproductive structure, the colossal squid probably has a penis. In addition, the adult male has spermatophores, which are 17 to 27 cm long. As for the mature female, it is larger than the male and has ovaries. These produce between 6,000 and 8,000 eggs, approximately 3 millimeters in diameter..

Because the adult habitat is meso and bathypelagic, scientists have had difficulty observing the reproductive process. However, based on the reproductive anatomy and behavior of other squids, experts hypothesize that the male uses the penis to directly implant spermatophores into the female..

State of conservation

Exhibit of a colossal squid at the Te Papa Tongarewa museum in Wellington, New Zealand. Source: Y23 from English Wikipedia, CC BY-SA 3.0, via Wikimedia Commons

IUCN has categorized the Mesonychoteuthis hamiltoni as a species at risk of extinction. Although the risk of disappearing is low, there are several factors that threaten the populations of this cephalopod.

Thus, occasionally, the colossal squid can be caught incidentally. Furthermore, as a marine animal, its development can be affected by water pollution. This leads to the degradation of their natural habitat and the premature death of some species.

In relation to conservation actions, there are no concrete measures. Protectionist organizations suggest conducting research studies where the distribution, ecology and life history of this cephalopod are studied..


The young colossal squid lives mainly from the surface of the water to a depth of 500 meters. The reason for this behavior is related to the abundance of prey. Thus, the juvenile has a greater chance of nurturing between the hatching period and its migration to deep waters..

In the late juvenile stages, the Mesonychoteuthis hamiltoni make a descent to around 2,000 meters. This movement towards deeper waters could be associated with the reduction of the possibility of being sighted by predators.

Thus, this species spends much of its life in the meso and bathypelagic areas of the Southern Ocean. However, the females that have been captured are in shallower water. This could suggest that the pregnant female migrates to spawn, as do other species of the Cranchiidae family..


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