Cuttlefish
By Dunya, Year 6
Cuttlefish are intelligent invertebrates (animals without backbones) that live in seas and oceans. Like their closest cousins, octopuses and squid, they are molluscs. I found Cuttlefish very interesting to write about because they have such a different lifestyle to most animals and once I went fishing and caught a Cuttlefish, when I saw how it moved it was quite weird so I decided to look further into this species.
It has a short life span, but they grow quickly even though they live for about 1 to 2 years.
This species can be found in most marine habitats from shallow seas to deep depths and in cold to tropical seas. It typically spends the winter in deep water and moves into shallow coastal waters to breed in the spring and summer. The common cuttlefish spends much of its time resting on the seabed, but it swims when hunting. They tend to sleep at the bottom of the ocean hiding themselves in coral and camouflaging only leaving their eyes out to see.
They have a fin fringe running along their sides. By undulating these fins they are able to hover, crawl and swim. They can also move by ‘jet propulsion’, which can be an effective escape mechanism. Jet propulsion is when the cuttlefish forces a jet of water out of its body, which pushes it along.
They have large, W-shaped pupils, eight arms, and two tentacles, with which they secure their prey with. They generally range in size from 15 to 25 cm, with the largest species, Sepia apama, reaching 50 cm in length and over 10.5 kg. Their brains are extremely big and their eyes work just as well as our own.
The colour of the cuttlefish could be brown, red, white, grey, metallic or a mix of two colours. The skin of cuttlefish changes colour rapidly using elastic pigment sacs called chromatophores. When that muscle relaxes, the chromatophore closes back up, and the colour disappears.
They eat small crabs, shrimp, fish, octopus, worms, and other cuttlefish. Their predators include dolphins, sharks, fish, seals, seabirds, and other larger species of cuttlefish.
