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10 Unique Characteristics of Squid

The characteristics of squid are very similar to those of octopuses and cuttlefish since they are both cephalopods. However, they also have multiple differences that make them unique from one another.

Over 300 species of squids are found worldwide, and while they differ slightly, most share these qualities. Make sure to check out these 10 traits that squids possess.

10 Characteristics of squid

Characteristics in animals

The following squid characteristics are both physical and behavioral. This animal’s physical characteristics include everything visible in its physical body, such as its eyes, hearts, and brains.

On the other hand, behavioral characteristics show how they react to specific situations, such as their ability to hunt and escape predators.

1. Squids are mollusks

Squid underwater
Squid underwater | image by NOAA Ocean Exploration via Flickr | CC BY-SA 2.0

Squids are mollusks, which are a type of invertebrate. This means they lack a backbone and have an unsegmented soft body. They also have bilateral symmetry, which means that if you cut a squid in half down the middle, each half will look exactly like the other.

These animals also have internal shells, and their mantle houses their internal organs, allowing them to function properly. Inside their beaks, they have a tongue with sharp teeth. These teeth aid in the breakdown of their prey prior to swallowing it.

Lastly, squids have an internal shell called a pen that protects the internal organs. All of these characteristics confirm that squids are a type of mollusk.

2. They have three hearts

Squids are cephalopods, and one of their characteristics is that they have three hearts. The systemic heart, which is located inside the mantle, is the most prominent heart in the squid. This heart is bigger than the others and is in charge of pumping oxygenated blood throughout the body and other organs.

The branchial hearts, or second and third hearts, are located at the base of each gill. This heart is in charge of delivering blood to the squid’s gills.

3. Squids have two fins to help with swimming

Squid swims underwater
Squid swims underwater | image by [cipher] via Flickr | CC BY-SA 2.0
Squids have two fins that they use to steer and stabilize their position. Squids, unlike octopi, don’t have a very flexible body, so having fins is an important adaptation for them as it allows them to move in any direction without relying on other external forces. This means they can move quickly in any direction, increasing the likelihood that they’ll be able to escape predators.

Squids can steer themselves by moving their fins up and down in addition to moving quickly in any direction. This allows them to stay stable while swimming and use their fins as rudders when swimming quickly through the water.

4. Squids have massive eyes

Squids have amazing eyes. They’re enormous, which helps them see in the deep sea, but they can only see in black and white because they only have one type of color-sensitive protein.

However, they have a unique ability to mimic and detect the color of their surroundings despite only seeing black and white. Their eyes are also enormous because vision is important to them. In fact, the largest eyes in the animal kingdom are found in colossal squids.

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5. Squids have eight arms and two long tentacles

Sculpture to scale of a Giant Squid battling a Sperm Whale in the American Museum of Natural History
Sculpture to scale of a Giant Squid battling a Sperm Whale in the American Museum of Natural History | image by Ryan Somma via Flickr | CC BY-SA 2.0

Squids have eight arms and two tentacles that work together to serve a single purpose, which is to capture and feed on prey. The tentacles are long and thin, with suckers at the ends that help them catch prey. On the other hand, the arms hold onto it while bringing it into their mouth.

Squids eat crustaceans and small fish. They catch their prey by wrapping their tentacles around the animal’s body and pulling it towards the squid’s mouth, where it’s torn apart by its beak, which is located in its mouth.

6. They have sophisticated nervous systems and complex brains

Squids, like other cephalopods, have nine brains and 500 million neurons. This makes them one of the most complex-brained animals studied by neuroscientists.

In fact, squids’ brains are much more complex than rats’ and may be on an equal level with dogs in terms of intelligence. These animals are adept at social communication with other squids and can effectively convey their messages.

7. Squids use jet propulsion to swim

Squids on sea bed
Squids on sea bed | Image by sailormn34 from Pixabay

Squids move through the water using jet propulsion. The siphon of a squid is a tube that extends from the squid’s body and propels it through the water. The siphon has two openings: one on top of the head and one just beneath the mantle collar.

When you see a squid swimming in a straight line, it’s actually moving backward because its siphon is pointing in the opposite direction. The siphon moves forward by pushing water into its body cavity and then expelling it again.

This produces an outward force on both sides of the squid, propelling it through the water like a jet. With jet propulsion, the squid can swim at a speed of 25 miles per hour.

8. The ink they produce acts as a defense mechanism

Squids have a unique survival adaptation known as inking. Inking is when they squirt ink, which can help them escape predators or hide from predators. It’s common in cephalopods living in the deep sea or low-light environments.

However, squids don’t use their ink every time they feel threatened because it requires a lot of energy to produce. They’ll only do so if they’re extremely scared or need to flee from danger as soon as possible.

Squids also use their ink to confuse or distract large prey before attacking them, making it difficult for them to escape.

9. Some species are bioluminescent

Squid in deep ocean
Squid in deep ocean | image by NOAA Ocean Exploration via Flickr | CC BY-SA 2.0

It’s no surprise that some squids can generate their own light. Some squid species, particularly those that live in dark environments, use this ability to attract prey. They’re able to do so by employing photophores, which are light-producing cells.

These photophores are found throughout the squid’s body, including its fins and body. When excited, these photophores can emit a bright glow that attracts fish and even scares away predators. They use this light to communicate with other squids as well.

10. Ability to change their body color to adapt to their environment

To adapt to their surroundings, squids can change their body color. They accomplish this by altering the amount of pigment in their skin, which is known as chromatophores. Chromatophores contain pigments that change color when stimulated by nerve impulses from other parts of their bodies.

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When stimulated by light or chemicals in their environment, these cells expand or contract, causing their color to change. Squids can use this to camouflage themselves and hide from predators like sharks and dolphins.

This also aids in their ability to blend in when they need to hide or draw attention when they want to eat something.

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