Last Reviewed and Updated on March 5, 2023
Squids are fascinating creatures with quite a few pretty interesting features, such as the ability to change color and shape in milliseconds. Let’s look at some fun facts about squids, one of the most intelligent animals in the sea.
1. They have blue blood
Unlike humans and most animals, squids’ blood is blue. Most animals, as well as humans, have iron-based blood, which gives our blood red color. Squid and many other mollusks have copper-based blood which makes their blood blue or bluish color.
2. All living squid species have 8 arms and 2 tentacles
All living species of squid have a set of 8 arms as well as a set of two distinctive tentacles. The two tentacles are longer than the arms and are retractile. All of their limbs are capable of grasping things.
3. They have 3 hearts
Just like the octopus, a squid has 3 hearts. They have the main heart (systemic heart), which is responsible for pumping blood around the squid’s body. The other two hearts, the branchial hearts, pump blood specifically to the gills. The blood gets oxygenated in the gills and then returns to the main heart.
4. Their arms can grow back (and maybe some other parts too)
They are able to regenerate their lost limbs. They are able to regrow both their arms and their tentacles. It is possible they have the ability to regenerate other parts of their body as well, but there haven’t been many studies made about this, so it remains unknown.
5. The Colossal squid is the world’s largest invertebrate
Invertebrates are animals without a backbone, and the largest of them all is the Colossal squid. This fairly recently discovered species is the largest known squid; it can weigh at least 1,091 lb / 495 kg but probably weighs a lot more. The maximum length is estimated to be up to 46 ft / 14 meters.
Not a lot is known about this species, as not many specimens have been observed. Two Colossal squids, captured in 2003 and 2007, are on display at a museum in New Zealand.
6. The Colossal squid has the largest eye in the animal kingdom
This is one of the most interesting facts about squids. It is about the size of a soccer ball. No other known animal species, living or extinct, had larger eyes.
7. Squids have a donut-shaped brain
This is one of the most interesting facts about squids. Their brains are shaped like a donut. Their brains are complex, and they are considered highly intelligent animals. Oddly enough, their esophagus runs through the (donut) hole in their brains. If they swallowed chunks of food that were too large, they would risk brain damage.
8. Vampire squid isn’t a squid
One of the coolest-looking squid-like animals isn’t actually a squid. It is closely related to squid and octopus but different enough to be in its own order.
9. Some squid species are bioluminescent
Many species of squid, event the giant squid, are bioluminescent. Squid uses bioluminescence for hunting their prey and as a means of defense as well as for communication.
The light is mostly produced by symbiotic bacteria within the specialized organ called the photophore.
10. All squids have ink
Squids use their ink mainly to obscure the predator’s view while they make a run for it.
11. They are fast swimmers
They are fast and agile swimmers. Squids can use jet propulsion. They fill its mantle cavity with water and then quickly expel it, jetting themselves in the water. These animals can also manipulate the shape of their body, making themselves more streamlined to move even faster.
12. Humboldt squid hunt cooperatively
These squids have been observed both hunting alone and cooperatively in groups.
13. Squid can change color
Only a few animals can change their color, and squid is one of them, and they can change it super fast. It only takes them one-fifth of a second to change the color of their skin.
The extent of color change depends on the species.
14. Flying squid can “fly” impressive distances in air
Using jet propulsion, the Japanese flying squid can jump out of the water and “fly”. Some other species of squid are capable of short jumps too, but none can match the flying squid as it has been observed to cover distances of about 100 feet / 30 m.