Squid | Nature Adventure

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Biology

Squids are often confused with their cousins, the octopus, but there's actually a number of differences between the two species! Squids usually have longer, more triangle-shaped bodies. They can be significantly bigger than octopus, with the colossal squid being a staggering 33 ft (10 meters) in length! They also different in the number of limbs they have, with both animals possessing eight arms, but squids having an extra two tentacles, which are longer than the rest of their limbs. These act as "catchers" for their prey!

The suckers on squid arms and tentacles also usually have little hooks, almost like teeth. They may have these suckers on all arms, only a few, or only on the tentacles, depending on the species!

There is a lot of variation among squid species, with sister families like the cuttlefish and bigfin squids looking extremely different to those that you might see sold in a supermarket. Their body types vary to strange extremes, from the very smallest to extremely large, and all kinds of shapes in between!

Like the octopus, squid can also change their colors to camouflage into the environment. This is possible due to special cells called chromatophores. By expanding or shrinking these cells, the squid can rapidly change colors and patterns to match their surroundings, or even create a strobe-like effect to confuse predators!

Squids are also known to create a cloud of ink when pursued, which is a collection of melanin particles that are ejected into the ocean from their ink sac! Since the concoction is also an alkaloid, this confuses predatory fish that who on chemical sensors to find their prey!

Ecological Importance

Squid are both predators and prey within the ocean ecosystem. They're mainly notable for being a key component to the diets of most larger species. Nearly everything eats squid if they're the right size for it, and for animals that are smaller, they are eaten by the squid. As one of the ocean's most abundant and universally-eaten food sources, they help to keep creatures in the ocean fed. Even the enormous giant squid is eaten by the great sperm whale!

Not every job is as impressive as those of the apex predators, but being a food source is every bit as important to the ecosystem. Managing healthy stores of prey species is the only way to support the bigger predators of the ocean!

Did you know?

Hawaiian bobtail squid take their color-changing a step further, using bacteria to produce bioluminecent light!

These squid have a symbiotic relationship with the bacteria Aliivibrio fischeri, which produces its own light. They live inside the squid's mantle, the long "head" part of the squid's body, in a special light organ that's visible through the squid's skin. In return for their light, the bacteria get to eat the sugars and amino acids produced in this organ. All they have to do is match the same amount of light hitting the top of the mantle, which camouflages the bottom of the squid from any predators that may be looking up! This is called "counter illumination".

At night, the squids leave their hiding places and roam the sea in search of food. This is when they turn on the lights, allowing them to disappear against the moonlight hitting the surface of the water. By dawn, the squid "vents" out around 90% of this bacteria into the water in order to regenerate a fresh colony by nightfall.

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