Cuttlefish – Part one: (Distribution – Description – Ink – Changing color – Swimming) – Video


This video was filmed in the Sea World (San Diego, USA) by the founder of this channel during January 2015.

Review: Abdel Rahman El Gamal (Founder of the video channel)


Introduction:Cuttlefish are small to medium sized marine animals that belong to the class Cephalopoda, which also includes squids, and octopodes. Despite their name, cuttlefish are not fish but they are molluscs.

There are more than 100 species of cuttlefish which significantly vary in size from the small ones of about 15 cm in length to the Australian giant cuttlefish which can grow to up to about 50 cm in length (excluding its tentacles) and about 10 kg in weight.

Based on research findings, cuttlefish have one of the largest brain-to-body size ratios of all invertebrates indicating that cuttlefish are among the most intelligent invertebrates.


Distribution and habitats:The family Sepiidae, which contains all cuttlefish, is found in shallow temperate and tropical waters. The wild cuttlefish are totally absent from the Americas except in aquariums and at research facilities. They are present along the coasts of East and South Asia, Western Europe, the Mediterranean, and all coasts of Africa and Australia. Even though they may go to depths of about 600 m, they are mostly shallow-water animals.


Description: The cuttlefish generally range in size from 15 to 25 cm (with some exceptions). They possess a unique internal structure known as a cuttlebone, which is porous and is made of aragonite. The cuttlebone which is filled with gas aids the buoyancy of cuttlefish. The cuttlefish have ten tentacles, out of which 2 are longer and used in grasping and securing their prey. Tentacles have suckers that extend over most of the length of their arms and along the distal portion of their tentacles.

Compared the cephalopods in general, cuttlefish have the best eyes, which are highly complex. They can see light that is invisible to humans. The shape of cuttlefish pupils helps control the intensity of light entering the eye.

The blood of a cuttlefish is an unusual shade of green-blue because it uses the copper-containing protein haemocyanin to carry oxygen. Their blood must flow more rapidly than that of most other animals because haemocyanin carries substantially less oxygen than the vertebrate’s hemoglobin.

Cuttlefish and ink:The cuttlefish dark-brown ink was once an important dye and used extensively for writing and drawing, and drawing, and can be used to treat medical conditions and as a food coloring. Today, artificial dyes have mostly replaced natural sepia.

Cuttlefish eject their ink into the water in a form of protective dark brown ‘cloud’ to help evade and fool incoming predators and/or allows them to hide or escape.

This ink which is composed mostly of melanin is stored inside an ink sac. It has been estimated that a single cuttlefish can cloud up to 20 cubic meters of water with ink.

Cuttlefish and changing color:Cuttlefish have remarkable ability to instantly change their skin color and color pattern. This ability make the animals blend with their surroundings not only for camouflage but also for communication such as during mating. The pigment cells (chromatophores) are responsible for releasing the pigment into the outer layer of animal’s skin.

The pigmented chromatophores with its variety of colors (e.g. yellow, red, orange, brown, black, blue and green) can -when used in combinations- are responsible for the numerous colors which cuttlefish can display. It is claimed that cuttlefish are the fastest color changers in the whole animal kingdom.

Swimming: Cuttlefish use their fins that surround their body for swimming. When quick movement is needed, they can rapidly expel water and move quickly by jet-propulsion. The bony structure “cuttlebone” is used to regulate buoyancy using chambers that may be filled with gas and/or water depending on where the cuttlefish is in the water column.


References: A-Z Animals, ARKIVE, BBC Nature,, Monterey Bay Aquarium, Wikipedia


Note: Part two on cuttlefish covers feeding, reproduction and utilization




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