What are Cephalopods?

Facts about Cephalopods around Koh Tao

What Is A Cephalopod?

A cephalopod is part of the family of animals called mollusks, which includes everything from snails to scallops. However, it’s a smaller segment of this population. The three main creatures that you know from this group are octopus, squid and cuttlefish.


Cephalopods always live in marine water (not fresh water) but may live anywhere from close to the surface to very, very deep in the sea. Many of these can be found around the dive sites here in Koh Tao.

Here are a few fun facts about Cephalopods….

Female cehalopods can be twelve times larger than males! This is not always the case. All cephalopods have male and female sexes in the species and sometimes they are very close in size and appearance. However, they are sometimes very different from one another! One example of this is the Argonaut Octopus, the male is only about one inch long and shell-less while the female is more than a foot long and has a shell.

Cephalopods change colour when mating. When a male squid is interested in mating with a female squid, the male will have a colourful patch on his back. This is due to sacs of colourful pigment inside of cephalopods, which can change from many colours to a single colour.


When the squids mate, the male will turn a dark maroon colour while the female will turn a pale white, almost as though he has sucked the blood right out of her. Many cephalopods die after mating.

Cephalopods have beaks and tongues. The mouth of a cephalopod has a beak around it that is similar to the shape of beak that a parrot has. Inside of the mouth is a hard tongue. When a cephalopod captures its prey, the beak and the tongue breaks open the shells or bones of the prey. So it’s not the tentacles that you need to be afraid of!

Cephalopods have poisonous spit. In many cases the cephalopod can use its beak to break open its prey and then inject poison into it. The poison is stored in the creature’s salivary glands.

Cephalopods are predators. Cephalopods eat crab, shrimp and various types of fish. They also eat other creatures from their own family, in some cases, they even eat other cephalopods.

Cephalopods can grow as large as sixty feet and weigh more than half a ton! This obviously isn’t common, but there is one type of cephalopod, the Giant Squid, that can reach these sizes. Even at about half that size, the 600-pound North Pacific Giant Octopus is something that a lot of us would love to come across in our dives. At the other end of the scale, there are some cephalopods that are smaller than your little fingernail.


Cephalopods have the superhero trait of jet propulsion! Basically there is a funnel-shaped organ inside of the body of a cephalopod that exhales water that the creature sucks into its body and when this happens it causes a burst of speed. In fact, some cephalopods can propel themselves out of the water.

Jet propulsion is typically used as an escape mechanism and it sometimes coincides with the release of ‘ink’, which is something most of us do know about squids.

Cephalopods can break off their arms and regenerate new ones. You know how there are lizards that can shed their tails to get away from predators and then grow a new tail in its place? The same is true of some cephalopods, although again, it’s not going to be true of all of them. Some octopi have been known to intentionally shed an arm and several types of cephalopods are able to re-grow limbs that have been lost.

There are some even wilder species than the ones that have these basic common traits. For example, there is the sword tail squid, which has a super long and thin tail that looks like a worm. And there’s the cock-eyed squid, which has one tiny, small, blue eye that is sunken into its body and one huge, yellow eye that protrudes from the body.


Their alien-like features are truly fascinating and cephalopods are commonly regarded as the most advanced of all invertebrates, all this makes cephalopods some of the most interesting things to see on the reefs around koh Tao. If you meet one during a dive, stop and take your time without disturbing it, you’ll observe some interesting behaviour and some colourful displays.

Author: Andy McEvoy (PADI MSDT)

Crystal Dive Koh Tao

7/1 Moo 2
Tambon Ko Tao
Koh Tao
Surat Thani

E-mail: info@crystaldive.com

Social networks