Latin Name: Sepiida
Location: Indo-Pacific Ocean, Red Sea, NW Australia. Can also be found as far North as Japan.
Size: 8cm-50cm (different species, different size)
Fun Fact: They have three hearts
Appearance
There are many different species of cuttlefish, so their size would depend on which one you are referring to. The smallest cuttlefish is the Flamboyant Cuttlefish – Metasepia pfefferi, measuring a mere 8-10cm long. The largest cuttlefish is the Giant Cuttlefish – Sepia apama, which can get up to an impressive 50cm long.
They have 8 arms and 2 tentacles with suckers which are essential for capturing prey. Cuttlefish are masters of camouflage, not only can they change the colour of their skin, but they can also change the texture of their skin, which enables them to blend into their surroundings. To do this they use chromatophores, which are balloon-like muscles in their skin that can expand to different shapes and sizes. Cuttlefish are colourblind! So how are they able to blend into their background if they can’t see colour? Well, they are able to determine their background by the amount of light that they can see because each colour gives off a different wavelength.
Cuttlefish are able to change the shape of their pupils. When you look at cuttlefish you will notice that they have a ‘W’ shape pupil, this is so they can see in front and behind at the same time, giving them the ability to swim in any direction. The ‘W’ pupil also lets light in from different angles, which is how they are able to blend into their background without being able to see colour. At night the pupil will change shape to become more circular, this is to maximise the amount of light let in
Blue Blood
The cuttlefish has blue blood due to the high amounts of copper in it. They also have three hearts. Two of the hearts pump blood to each pair of gills and the third heart pumps blood around the rest of the body.
Masters of Buoyancy
What makes the cuttlefish different to the other cephalopods is its cuttlebone. They have one single ‘bone’ in their body to help maintain their buoyancy. Composed primarily of calcium carbonate. The cuttlebone is made up of tiny chambers that can either be filled with air or liquid. By adjusting the ratio of air to liquid, cuttlefish are able to control their buoyancy. More liquid makes them negatively buoyant – causing them to sink – while more air enables them to rise.
Have you ever wondered why there are deep sea squid and deep sea octopus, but never a deep sea cuttlefish? The cuttlebone is the reason. As you descend deeper into the ocean, pressure increases, which would crush the cuttlebone. Therefore, cuttlefish need to remain in shallower waters.
Diet and Hunting
Cuttlefish are carnivorous, with a diet consisting of small fish, molluscs and crustaceans. They have a beak similar to a parrot, so they are able to break into the shells of their prey.
If you’ve ever been lucky enough to see a cuttlefish hunting, it is an amazing site. They will use their camouflage to sneak up on their prey, they will extend out their tentacles and launch a swift attack when they are close enough. Sometimes they will rapidly change their skin colour to hypnotize and entice their prey.
Breeding (The Sneaky Males)
Like most animals, the male needs to impress the female. He generally tends to be bigger than the female, so that he can offer protection and fight off any rivals.
When it comes to mating, the male will stay close to the female. Sometimes this can be overwhelming for the poor guy as there will be many males trying to compete to get close to the female. He will try and fight off as many males as he can. Whilst the big male is distracted, a smaller male will disguise himself as a female to try and get past the fighting males, and this does work! It works so well, that even if the dominating male is not distracted, the smaller male will slip right past him to get close to the female to mate with her. She will attempt to mate with multiple males in order to increase genetic diversity among her offspring.
Seen as intelligent animals, these guys tend to live on their own. Socialising is seen as a mark of intelligence in animals, cuttlefish and their relatives, like octopuses, tend to to be solitary except during mating seasons. They possess a high brain-to-body ratio and display problem solving abilities.
The cuttlefish stands out as an extraordinary marine creature with unique adaptations, such as the ability to change the shape of their pupils and remarkable camouflage capabilities, despite their inability to see colors. Encounter one during a dive, and take a moment to marvel at its fascinating behavior and features.