Fascinating creatures indeed bentley!
Cuttlefish belong to the Cephalopoda class and includes squid, octopuses, and nautiluses). Although they are known as fish, they are mollusks and not fish! Recent studies indicate that cuttlefish are among the most intelligent invertebrates. Internationally there are 120 species of cuttlefish recognized. I am not sure how many species are in South African waters though!
Cuttlefish have eight arms and two tentacles furnished with suckers, with which they secure their prey.
They have a life expectancy of approximately 2 years and feed on small mollusks, crabs, shrimp, fish, octopuses, worms, and other cuttlefish. They are being preyed upon by dolphins, sharks, fish, seals and other cuttlefish.
Their cuttle-bones are porous and used for buoyancy by changing the gas-to-liquid ratio in the chambered cuttle-bone.
Cuttlefish eyes are among the most developed in the animal kingdom.
The blood of a cuttlefish is an unusual shade of green-blue. The reason for this is the fact that they use the copper containing protein hemocyanin to carry oxygen instead of the red iron-containing protein hemoglobin that is found in mammals. They have 3 separate hearts to pump their blood. Two hearts pump blood to the pair of gills and the third pumps blood to the rest of the body.
Photo of 2 Cuttlefish:Herewith something interesting facts about their ability to change colours:Cuttlefish are sometimes referred to as the chameleon of the sea because of their remarkable ability to rapidly alter their skin color at will. Their skin flashes a fast-changing pattern as communication to other cuttlefish and to camouflage them from predators. This color-changing function is produced by groups of red, yellow, brown, and black pigmented chromatophores above a layer of reflective iridophores and leucophores, with up to 200 of these specialized pigment cells per square millimeter. The pigmented chromatophores have a sac of pigment and a large membrane that is folded when retracted. There are 6-20 small muscle cells on the sides which can contract to squash the elastic sac into a disc against the skin. Yellow chromatophores (xanthophores) are closest to the surface of the skin, red and orange are below (erythrophores), and brown or black are just above the iridophore layer (melanophores). The iridophores reflect blue and green light. Iridophores are plates of chitin or protein, which can reflect the environment around a cuttlefish. They are responsible for the metallic blues, greens, golds, and silvers often seen on cuttlefish. All of these cells can be used in combinations. For example, orange is produced by red and yellow chromatophores, while purple can be created by a red chromatophore and an iridophore. The cuttlefish can also use an iridophore and a yellow chromatophore to produce a brighter green. As well as being able to influence the color of the light that reflects off their skin, cuttlefish can also affect the light's polarization, which can be used to signal to other marine animals, many of which can also sense polarization.