The colossal squid, scientifically known as Mesonychoteuthis hamiltoni, is a fascinating and elusive creature that inhabits the frigid depths of the Southern Ocean. Often referred to as the Antarctic squid or giant cranch squid, it holds the title of the largest invertebrate by mass, captivating scientists and enthusiasts alike. This article delves into the dietary habits of this mysterious giant, exploring what it eats, who its predators are, and how its diet contributes to its unique place in the Antarctic ecosystem.
Colossal Squid Profile
Mesonychoteuthis hamiltoni is a deep-sea squid that occupies some of the coldest, darkest parts of the Southern Ocean (also known as the Antarctic Ocean). They are sometimes referred to as the giant cranch squid and the Antarctic squid. It’s the largest squid species by mass and is believed to weigh up to 700 kg (1,500 lbs) and grow as long as 10 meters (33 feet).
Colossal Squid Facts Overview
- Habitat: Deep ocean, shallower when juvenile
- Location: Southern Ocean
- Lifespan: Unknown
- Size: 30-33ft (9-10m)
- Weight: 1090lb (495kg)
- Color: Red
- Diet: Fish
- Predators: Numerous, sperm whales, large fish, birds
- Top Speed: Slow
- No. Least Concern
The Colossal Squid: An Enigmatic Giant
Antarctica is home to some of the weirdest and most mysterious animals on earth. An entire continent, uninhabited by humans, left under the ice for 34 million years, and only visited by a handful of scientists (and Metallica that one time). There’s a lot going on in Antarctica that we’re only just finding out about, and some of it involves the heaviest invertebrate ever recorded. The colossal squid is also an intelligent, elusive predator with the largest eyes in the animal kingdom. Although we don’t know much about it, we can assume from its cousins that the colossal squid is likely to be pretty intelligent, despite it being related to a garden snail. This enormous cephalopod is shorter than its cousin the Giant Squid but much more buff. It has a wider body, which gives it the extra weight. Despite its size, it only seems to bother hunting fish, but it is itself hunted by numerous predators at every stage of its life cycle. Like other squid, it has eight arms, two tentacles, a head, a beak, and fins.
What's on the Menu? The Colossal Squid's Diet
The colossal squid is a carnivore with a diet primarily consisting of fish. They mainly diet on Antarctic toothfish, but will also consume other large fish and smaller squid. They have been known to pluck the toothfish from fishing lines.
A recent study revealed that Antarctic toothfish make up a significant part of the colossal squid's diet; of the 8,000 toothfish brought aboard trawlers between 2011 and 2014, seventy-one showed clear signs of attack by colossal squid. Squid remains in a female colossal squid's stomach suggest the possibility of cannibalism within this species.
Read also: Risks of Eating Squid
Scientists have opened the stomachs of giant squids washed up on beaches to see what they ate, even though they haven’t witnessed them feeding in action. Giant squid frequently prey on large sea creatures such as deep-sea fish, young sharks, and other large sea animals. They can even prey on other squid as well. Because of its enormous size, the giant squid is one of the most aggressive hunters on the planet. As a result, it is free to eat whatever it wants.
Hunting Strategies
It is presumed to be an ambush predator, using bioluminescence to attract prey. The colossal squid has the largest eyes of any known creature. Their eyes can also glow in the dark! This is because they have special parts called photophores.
Squid can snatch prey up to 33 feet (10 meters) away by shooting out their two feeding tentacles, which are tipped with hundreds of powerful sharp-toothed suckers. Eight thick arms speckled with 2-inch wide toothed suckers guide prey from the feeding tentacles to a sharp beak in the center of the arms, where the prey is sliced into bite-sized pieces. The squid’s beak is sharp and parrot-like, and is located near its mouth. It uses this technique to shred the prey before devouring it. It also has a tongue-like structure with teeth that are similar to file teeth. They perform like grinders, reducing the food to tiny little pieces before it is ingested.
Cannibalistic Tendencies
One of the reasons for hatching colossal squid eggs in the shallows may be to avoid predation from other squid. While there are a lot of planktonic and small larvae up there for the young to feed on, they’re also avoiding the much larger and cannibalistic adult squid. Remains of other squid have been found inside adult specimens.
Trophic Level
Studies measuring the δ15N content of the chitinous beaks of cephalopods to determine trophic ecology levels have demonstrated that the colossal squid is a top predator that is positively correlated with its increased size.
Read also: The Diet of Humboldt Squid
Predators of the Colossal Squid
As mean as this monster sounds, it’s preyed upon by a surprising cohort of birds, whales, and fishes. So far, 17 predator species have been found with colossal calamari inside them. Colossal squid are thought to be major prey for sperm whales in particular, which are the largest of the toothed whales, which can reach over 20m in length.
Many other animals also feed on colossal squids. Other animals that might hunt colossal squids include the pilot whale and killer whales. Large southern elephant seals, Patagonian toothfish, southern sleeper sharks (Somniosus antarcticus), and Antarctic toothfish also prey on them.
Sperm whales who prey on colossal squid have been found with scars on their backs from colossal squid using their hooks in defence. Colossal squid are a major prey item for sperm whales in the Antarctic; 14% of the squid beaks found in the stomachs of these sperm whales are those of the colossal squid, which indicates that colossal squid likely make up 77% of the biomass consumed by these whales. Many other animals also feed on colossal squid, including the beaked whales, such as southern bottlenose whales, and Cuvier's and Baird's beaked whales. Other possible predators include the pilot whale, killer whales, larger southern elephant seals, Patagonian toothfish, southern sleeper sharks (Somniosus antarcticus), Antarctic toothfish, and albatrosses (e.g., the wandering and sooty albatrosses).
Predator-Prey Dynamics
The largest eyes on the planet didn’t evolve for finding prey in the dark. It seems like they’ve evolved to be 27cm in diameter in order to adapt to spotting sperm whales descending to the deep. Sperm whales probably are the meanest fish in the sea, despite being mammals. They regularly enter the territory of the deep-sea monsters and it’s suspected they can incapacitate them with a powerful sonic shockwave.
Life Cycle and Habitat
The colossal squid lives mainly in the Southern Ocean. Its known home stretches thousands of kilometers north from Antarctica. Colossal squids are often seen near the Cooperation Sea. They are seen less often near the Ross Sea.
Read also: Marine Food Webs and Squid
The tiny eggs are thought to spawn in shallow waters and on hatching, the young spend their early lives at that depth. As they grow, they begin slowly sinking as they get older, with adolescents at around 6,500ft (2000m), ending up as adults in the murky depths at around 13,000ft (4000 meters)!
Reproduction
Scientists do not know much about how colossal squids reproduce. We do know that there are male and female squids. Young squids are thought to lay their eggs near the surface during the summer. The adult female colossal squid has been discovered in much shallower waters which likely implies that females spawn in shallower waters than their normal depth. Additionally, the colossal squid has a high possible fecundity reaching over 4.2 million oocytes which is quite unique compared to other squids in such cold waters. Colossal squid oocytes have been observed at sizes ranging from as large as 3.2x2.1 mm to as small as 1.4x0.5 mm. Sampling of colossal squid ovaries show an average of 2175 eggs per gram.
Conservation Status
Due to their habitat, interaction with humans or fishing is extremely rare. The colossal squid is listed as "least concern" on the IUCN Red List. This means it is not currently at high risk of disappearing. Fishermen do not usually try to catch colossal squids. They are only caught by accident when they try to eat fish caught on hooks.
Interesting Colossal Squid Facts
- They are the heaviest squid. They are thought to weigh up to 700kg (1,500 lbs) and grow as long as 10 meters (33 feet).
- As they grow, they sink.