When you see a group of squid together, you can call them a squad. As with other marine animals, you can also call them a school. There are more than 300 species of squid around the world, and they live in oceans and coastal waterways. A squid is considered a cephalopod and most likely have lived on the Earth millions of years before fish swam in the oceans.

Squid Population

Since the 1950s, the squid population has grown astronomically. Scientists don't know the exact reason for the boom, and speculation includes everything from natural ocean cycles to human fishing practices. Research suggests that if you weighed all of the humans on the planet and all of the squid in the ocean, the squid population would weigh more. Because they are so plentiful, they're often called the "weeds of the ocean."

Squid as Predators

Squid play an important part in the ocean's ecosystem, both as predators and prey. These carnivores feed on small fish, crabs, and shrimp. Squid are powerful yet patient hunters, and they sit still, stalking their prey until they're ready to grab them. Once the squid does grab its food with its tentacles, it chops it up into small pieces and eats it alive. Some squid also have toxins in their saliva.

Squid as Prey

While squid is one of the ocean's great hunters, it's also often hunted. Sperm whales are the squid's biggest predators. Sharks, dolphins, other types of whales, seals, and seabirds eat them too. To hide from predators, squid have several ways of camouflaging themselves, including counter-illumination. While some squid use lights from symbiotic bacteria and their own bodies to hide in the ocean, others distract predators by squirting ink at them.

Squid as Human Food

Beyond the ocean, humans enjoy eating squid, so it is often commercially fished. If you've ever eaten calamari in a restaurant, you've eaten squid — "calamari" is the Italian word for the animal. It's typically battered, deep-fried, and served as an appetizer. Spanish and Italian chefs add it to everything from soup to pasta. In many Asian cultures, the squid is grilled whole and eaten alone or in rice and noodle dishes.

Smallest and Largest Squid

Because there are hundreds of species of squid, there are quite a few differences between them, including size. True to its name, the largest squid ever discovered was a giant squid that was 43 feet long, and scientists believe it weighed about a ton. The smallest squid is the Southern pygmy squid, and it grows to be about 1.6 centimeters. The giant squid is the largest invertebrate on the planet.

Life Cycle of a Squid

Most species of squid don't live very long, usually dying right after spawning offspring. Some may live for a year, while others live for up to five years. Reproduction begins with a male squid meeting a female in open water and scaring off the competition before mating. Afterward, the female lays eggs, either on the ocean floor, on vegetation or simply in the middle of open waters, depending on the species. Many females lay up to 11 pounds of eggs.

Squid in Pop Culture

From Greek mythology to 19th-century literature, the squid has been well-represented in literature, art, and culture. This is especially true for the giant squid, which is often depicted as a sea monster in stories like Twenty Thousand Leagues Under the Sea by Jules Verne. H.G. Wells wrote about a man-eating squid, and Aristotle even wrote about giant squid back in the 4th century.