8 Squid Adaptations (Evolutionary Secrets!)

Squids are among the most successful creatures on the planet, as they existed for over 500 million years and survived huge changes on planet earth that many other creatures couldn’t.

They survived through all of this by developing evolutionary adaptations that have allowed them to evade predators and successfully hunt for prey.

If you want to know more about squid adaptations, keep on reading this handy guide as we walk you through 8 of the most impressive and critical ones. Let’s dive right in and see what this amazing creature has to offer!

Squid Adaptations

1. Excellent Eyesight

Kicking off the list with one of the most impressive adaptations of squids and cephalopods in general. In fact, squids have remarkably good eyesight, which is extremely essential given how deep in water some squids can be.

For starters, squids have very large eyes. In fact, they are some of the largest in all of the animal kingdom when compared to the size of their body. The largest eye to body ratio among all animals belongs to a squid species, known as the “Vampire Squid”, while the eyes of the “Giant Squid” can be as big as a Frisbee disc!

Size is not the only impressive aspect of their vision, but they also have thousands of highly sensitive photoreceptors in their eyes. These rod-shaped receptors allow them to see very well in extremely low light, although they can’t distinguish colors.

Moreover, squids don’t have blind spots in their eyes (most creatures, including humans have blind spots), so they have a full range of vision that makes them aware of their surroundings and capable of catching darting prey even at night, as most squids are nocturnal.

2. Changing Colors

Camouflage is essential for squids, whether it’s for escaping predators or catching prey, and like other members of the cephalopod family, squids can also change their colors!

This ability is all thanks to small sacs that are found in their skin, called “chromatophores”. These microscopic sacs contain various pigments that expand and contract at will.

Although cuttlefish and octopuses mainly change their colors to match their environment, most squids change colors in order to communicate with each other. Some squids are also able to go semi-transparent while swimming in open oceans.

Another feature that makes squids special is that some species also experience bioluminescence, which is the ability to grow in the dark using certain enzymatic and bacterial reactions inside the body.

The most notable example of squid’s bioluminescence is the firefly squid.

3. Tentacles and Suction Cups

While octopuses have eight limbs, squids have ten. These ten limbs are classified into two relatively large tentacles and 8 legs.

The difference between arms and tentacles is that an arm will be longer and covered with suction cups while tentacles are shorter and have suction cups only near the end of the limb.

Squid tentacles are also equipped with a few hooks that they use to immobilize prey before they eat them.

A squid will use its 8 legs to swim in open water. They will also use their arms to break their food apart and push the smaller pieces into their mouth.

4. Beaks

Speaking of their mouths, squids have sharp beaks, similar to the one parrots have. These beaks are quite powerful, which is necessary for breaking the shells of crustaceans like crabs and mollusk shells, their most common food.

In addition to crushing, they also use their beak for chewing. Despite being powerful, they have relatively small mouths, which is why they break their food into smaller pieces before eating it.

Squids also use their beaks to bite, and while all squids are venomous the level of toxicity of the venom varies greatly among species, just like other cephalopods.

5. Hydrodynamic Bodies

While squids can vary in shape depending on their species, they all share a common feature: Their bodies are usually shaped like a torpedo or a rocket, which gives them superior hydrodynamics.

 In fact, among all aquatic invertebrates out there, squids are the fastest. They have an average speed of around 18 mph (28.9 km/h).

This speed also helps them escape their predators quickly, including seals, dolphins, turtles, sharks, etc.

6. Jet Propulsion

Like other cephalopods, squids also managed to evolve one of the most impressive and effective forms of locomotion, which helps them escape danger pretty quickly.

Squids are capable of propelling their body forward by contracting their siphon tube, which is found on the ventral surface of the mantle. They shoot out a jet of water that helps them swim far away in mere seconds.

7. Ink Sacs

Octopuses aren’t the only creatures that can shoot out ink. Squids also have an ink sac, which they can release through their siphon tube when they’re threatened.

The ink sac is located near the squid’s gut. When they need to make a quick getaway, they release the ink into the siphon to be squirted out during the jet propulsion, which helps them to stay out of the predator’s sight for a valuable brief moment.

8. Three Hearts

Lastly, like their cousins, squids have one primary (systemic) heart and two secondary (branchial) hearts.

The function of the secondary hearts is to exclusively pump blood to the gills in order to draw as much oxygen from the water as possible.

The systemic heart, on the other hand, is responsible for pumping the blood to the rest of the squid’s body.

Squids also have hemocyanin as oxygen carriers, instead of hemoglobin, which gives their blood a characteristic blue color.


There are over 300 species of squid that have been discovered to this day and they’re classified as cephalopods, which makes them close relatives to octopuses and cuttlefish.

Squids are found in all oceans around the world, while individual squid species may vary, they all have an arsenal of adaptations that helped them survive their environments.

As you can see, there is no shortage of tricks up squids’ sleeves when it comes to adapting and surviving their environment, whether it’s to escape their predators or catch their prey!