Squids are cephalopods similar to octopuses and cuttlefish evolving as early as the Jurassic period. Their elongated bodies, eight arms, and two long tentacles give them that unique appearance. No wonder, in the past, squids were often associated with tales related to sea monsters. They have a significant role in the food web of their ecosystem, acting as predators to fish and crustaceans and prey to larger species like sharks and seals.
| Animalia | |
| Mollusca | |
| Cephalopoda | |
| Decapodiformes |
| Animalia | |
| Mollusca | |
| Cephalopoda | |
| Decapodiformes |
These mollusks can change color for camouflage and signaling, while many species can eject ink clouds to distract predators. Squid are rapid swimmers and move via jet propulsion.
There are over 300 species of squid worldwide. Here are some of them:
Size: Length: 0.75 in -46 ft (1.6-140 cm)
The smallest known squid is the Southern pygmy squid at 0.75 in, while the colossal squid is the largest, reaching around 46 ft.
Weight: 0.02 oz – 1100 pounds (0.566 g – 500 kg)
Body and Coloration: They have a soft, elongated, tube-shaped body called mantle, ending in a flattened head. Each side of the head has two large eyes giving them a 360°vision.
In the ventral part of their body lie eight arms and two long tentacles surrounding their mouth. The tentacles are of a greater length in comparison to their arms, also being retractile.
All of their ten arms (including the two tentacles) have disc-shaped suckers, with some of the suckers bearing hooks on them for a better grip.
The mantle contains most of their body mass, with a swimming fin along each side, though they are not the primary source of movement in most species. There are two feathery, white gills on both sides of the mantle.
Consistent coloration is not observed, ranging from sandy brown to vibrant red or ripple with bright metallic rainbows, due to the presence of chromophores, or color-changing cells.
Squids inhabit all oceans worldwide.
The habitat of different squid species varies, some living in warmer, tropical, shallow sea waters while others in the cold depths of the oceans. Some squids thrive in the seas of the polar regions.
Most squids live from 1-3 years, but some can live up to 5 years.
Carnivorous by nature, their diets mainly consist of fish and crustaceans like crabs. However, cannibalism has been observed in some species eating not only other squids but also members of their own species.
Some squids eat up to 30% of their total biomass, with certain species even eating more.
The predators differ from one squid species to the other, but penguins, seals, and sharks are common for most of them. The giant squid is a staple part of the sperm whale’s diet.
Courtship takes place in water, with the male squid selecting his mate of the opposite sex. They undergo elaborate courtship displays with males using a unique arm to transfer sperm packets to the females. Some species go through changes in their color, and body pattern during courtship, and mating, the Caribbean reef squid being one among them.
As the eggs pass through the female squid’s oviduct, they get coated in a gelatinous substance before reaching their mantle cavity where fertilization takes place. The mothers then lay hundreds of gelatinous eggs on the ocean, often in communal areas, hiding them under rocks or holes. After male and female mate, they both usually die.
After 4-8 weeks, baby squids hatch and are smaller versions of their parents. They feed on tiny creatures called plankton while they grow to adulthood. Very little is known about the life cycle of deep-water squid, though.
As per the IUCN, most species of squid do not have enough data to determine their conservation status, while those with enough data are considered “Least Concern” or “LC”.
Squids have two long tentacles, one of their main physical features. They even have eight arms, or precisely two legs, and six arms.
No, they do not possess either spinal cords or bones.
They are extremely fast, reaching speeds of 18 mph.
A group of squids is often referred to as a school, an audience, or a squad.
While not as smart as octopi, squids are believed to be as intelligent as a dog. Yes; they may not be at par with the octopus or cuttlefish in intelligence, and smartness. However. because of their increased social communications, and efficient problem solving skills, scientists have deemed them equivalent to dogs in smartness.
Some squids possess venom, but most are not dangerous enough to kill humans.
Unlike most invertebrates, squids have a more complex circulatory system, similar to humans, improving energy efficiency.
It is not recommended to keep squids as pets because they are short-lived, known to leap out of tanks, and eat any other occupants in the same tank as them.
