When people think about life under the sea, squid count as one of the first ones that come to mind. Some children even think of them as fish, despite them actually counting as cephalopods. Squids also count as one of the first that comes to mind when thinking about seafood. Learn more about this versatile cephalopod with these 40 squid facts.
- Most squid typically grow to around 60 cm long.
- The giant squid, though, can grow up to 13 meters long.
- Meanwhile, the smallest squids such as the pygmy squid, usually grow to only around 18 mm long.
- Fishermen catch an estimated 2.19 million tons of squid every year.
- Argentine shortfin squid make up the most common kind of squid caught every year, at an estimated 511,000 tons.
- The squid’s first ancestors first appeared during the Permian Period, around 300 million years ago.
- They also diverged from the octopus’ ancestors during this time.
- The first true squids first appeared during the Jurassic Period, around 200 million years ago.
- Squids flourished during the Cretaceous Period, around 145 million years ago.
- Aristotle first described giant squids in the 4th Century BC.
- Pliny the Elder also described giant squids in his work, Natural History, during the 1st Century BC.
- Squid as food in Europe spread from Italy across the continent during the 17th Century AD.
- In the 1970s, scientists launched a campaign to popularize squid as food in the USA.
- A giant squid cut up the hull of the warship USS Stein in 1978.
- A fishing boat caught the heaviest squid known, at 495 kg, in 2007 in New Zealand.
- The colossal squid from Antarctica has the biggest eyes in the entire animal kingdom.
- Squid makes up 96% of the elephant seal’s diet.
- Sperm whales can eat up to 800 squids in a single day.
- Longfin inshore squid makes up the least common squid caught every year, at only an estimated 17,000 tons.
- Squid have the protein tropomyosin, which causes allergies in some people.
Squid have very good camouflage.
For one thing, their skins have special cells like those which chameleons have, letting squid change their color to match their surroundings. Other cells also reflect light in special ways, causing a squid’s skin to change its patterns with every millisecond. Squid living in deeper waters can also produce their own light. They use this ability to blend in with the light coming from the surface above, making them invisible to prey and predators from below.
Squirting ink makes up the squid’s most well-known ability.
But as well-known as this ability is, squid uses it only for a simple purpose, that of escaping from predators. The ink also has a simple composition, primarily made from melanin, the same chemical that gives color to human skin and hair. When the squid releases the ink, it clouds the water, making it hard to see the squid and where it runs to. The ink also has special chemicals mixed in it, which scrambles a predator’s other senses, making it even harder for them to track the fleeing squid.
Squid have the most complex nervous systems among invertebrates.
They have a ring-shaped brain that surrounds their throat, and which they protect using an internal shell made from cartilage. Nerves not only allow them to see and react to information from their senses but also to consciously control their muscles.
Squid have blue blood.
This comes from the fact that their blood contains hemocyanin instead of hemoglobin, and which has copper, not iron. That said, both serve the same purpose of carrying oxygen around the squid’s body with the blood. Squid have three hearts, two of which specifically pump blood to and from the gills to pick up oxygen or dump carbon dioxide. The main heart solely has the task of pumping blood around the body after it returns from the gills.
Bacteria have colonies inside squid bodies.
We mentioned earlier how some squid can generate light with their own bodies, but not all squid do so using their own cells. The Hawaiian Bobtail Squid make up one of those, using symbiotic bacterial colonies to produce light for it. These colonies also strangely have varying sizes, as the squid actually expels up to 95% of the bacteria every morning. The population then builds up during the day and returns to full size by the time night falls. Scientists think this results as an indirect way for the squid to control the amount of light the bacteria produces for it.
Squid use water jets to move.
Squid literally inhale water into a special cavity inside their bodies and then expel it in a high-pressure jet. This causes the squid to jet through the water at high speed. The squid can adjust the direction of the jet as needed, as well as the amount of pressure. This, in turn, allows them to control their speed, as well as adjust their course through the water as needed. The fins on their head provide additional control for the squid to adjust their course, with the fins letting the squid adjust the way water flows around their bodies as they move.
All squid can fly.
Flying squid just tend to do it regularly, while other squid only do it to escape from predators. Squid use their water jets to jump out of the water, and then adjust their fins to work in the same way a bird or a plane’s wings do. This allows them to fly for distances of up to 30 meters, and even then, can adjust their fins to return back into the water safely.
Squid have many ways to hunt prey.
Their tentacles make up their main hunting tools, and which they can use very fast and very precisely. The tentacles don’t just wrap around prey, they also have suction cups or even hooks in some species, making a squid’s grip on its prey even more secure. Once caught, the prey then gets brought to the squid’s mouth, which features a powerful beak. The beak has both hardness and biting force enough to punch through steel, allowing the squid to eat just about anything it catches. It also lets the squid break up its prey into small bits and pieces, letting small squid eat larger prey. Some squids even have poisonous saliva, which lets them pacify a prey’s struggling so they can eat in peace.
Squid have unique mating behavior.
Males and females position themselves head-to-head against each other and lock their jaws together as well. Males will then use their tentacles to literally deposit their sperm into the females’ bodies. Females can store the sperm for some time instead of immediately letting it fertilize their eggs. Once fertilized, a female will eject its eggs into the surrounding water. Most squid bind the eggs together into a clutch, while others let them float freely with the water.
Differences exist between giant squid and colossal squid.
Another thing, giant squid tend to grow longer, but also lighter compared to colossal squid. Specifically, they can grow up to 13 meters long, while maxing their weight out at around 275 kg. In contrast, while colossal squid can only grow up to 10 meters long, their weight can max out at around 490 kg. Colossal squid also live only in Antarctic waters, even if every once in a while some specimens travel out into the surrounding southern oceans. In contrast, giant squid live all over the world, mostly in the North Atlantic Ocean, but many also live in the Pacific Ocean and Indian Ocean. Strangely, though, giant squid tend to rarely live in the South Atlantic Ocean, with scientists still unsure of the cause.
Humans took their first pictures of giant squid in the 2000s.
In 2001, scientists managed to film living giant squid larva in the wild, which later premiered on a show on Discovery Channel. Then in 2002, fishermen caught a 2-meter-long giant squid in Kyotango, Japan, and photographed it before its death. The Tokyo University of Fisheries later confirmed the specimen as a giant squid. Then in 2004, Japanese scientists managed to hook a giant squid’s tentacles in the wild. The giant squid eventually tore off its tentacle to break free, but not before the scientists took over 500 pictures of the animal.
Humans first caught colossal squids in the 1980s.
Soviets operating in the Antarctic Ocean managed to catch an immature female colossal squid in 1981, measuring over 4 meters long. Then in 1984, scientists caught a 6-meter-long colossal squid, with no succeeding catches made until 2005. In that year, scientists caught a colossal squid measuring 4.8 meters long.
Squid have had a place in fiction since ancient times.
Scholars actually think that the giant squid may have provided partial inspiration for the legend of Medusa. They also think that the giant squid had completely inspired the monster Scylla from Homer’s Odyssey. The Norse may also have based their myth of the Kraken from giant squid. In modern times, giant squid appeared in Jules Verne’s novel, 20,000 Leagues Under the Sea.
Chinese and Japanese cuisine have many ways to prepare squid.
In China, squid features heavily as an ingredient in various dishes, such as in noodles, rice, and stir-fries. In Japan, squid appears in almost every seafood dish, as well as its own dishes, such as squid sashimi among others. Grilled squid features in both Chinese and Japanese cuisine, while dried shredded squid remains a popular snack in both countries.
Korean cuisine also has its own ways to prepare squid.
San ojingeo features squid served fresh, usually alongside fresh octopus, and wrapped in either lettuce or pillard. The dish comes seasoned with chili sauce, Korean mustard, sesame sauce, and soy sauce. Other ways to prepare squid in Korean cuisine include frying it with batter, or minced and cooked as part of a pancake. Squid also comes as an ingredient in various spicy soups. Koreans also eat squid dried along with peanuts when drinking alcohol. Traditional Korean cuisine also features boiled or steamed squid as delicacies.
Squid makes up a large part of Mediterranean cuisine.
Calamari probably makes up the most popular Mediterranean dish featuring squid as an ingredient. It involves squid coated in batter and then quickly, usually for no more than 2 minutes, to keep the meat from getting tough and chewy. It also gets served plain, with salt and lemon to taste on the side. Other Mediterranean dishes include puntillitas from Spain, involving fried baby squid with batter. Another Spanish squid dish includes calamares en su tinta or squid stewed in their own ink. Both Spanish and Italian cuisines also feature squid in various other dishes, such as paella and risotto, among others. Greek and Turkish cuisines, as well as those of neighboring countries, such as Croatia, also feature squid stewed with vegetables, such as squash and tomato.
Russians have their own way of preparing squid.
First, they cut the squid into long thin strips before lightly boiling it and then serving it as a salad with onion rings, garnished with mayonnaise. Another Russian squid dish involves stuffing squid with rice and vegetables before roasting them together.
The term ‘calamari’ has a story behind it.
Scholars argue over where the English word comes from, with most believing it comes from the Italian calamaro, or in plural form, calamari. Other scholars point to the Spanish calamar or the Modern Greek kalamari as the origin of the English word.
However, in all cases, their root goes back to the Late Latin word calamarium, or inkpot. This goes back to the Classic Latin calamarius, or writing reed, referring to both the shape of the squid’s body, as well as the black ink it produces. In fact, Classic Latin developed the word from the Ancient Greek kalamos, meaning reed, or pen.
Squid have plenty of nutrition.
Protein makes up to 80% of a squid’s mass, with fat making up less than 20% of it. That fat even has low saturated content which is instead made up of Omega-3 and other similarly-healthy fatty acids. Squid also has naturally rich concentrations of phosphorus, along with trace amounts of calcium and B-Vitamins.
Scientists have studied squid to apply their discoveries in other fields.
Scientists at Bristol University currently study squid skin, in particular, its ability to change color at will. They hope to eventually use their findings to develop an artificial skin-like substance that can change color with various electrical signals. The American engineer Otto Schmitt also used his studies of giant squid nervous systems to develop the Schmitt Trigger for use in function generators.