The cuttlefish is a small cephalopod that inhabits all temperate oceans except those surrounding the Americas. Its mantle (body without arms) achieves a football's proportions.
Like other cephalopods, it keeps most of its organs in the
squishy sack above its eyes. The mantle is fringed on each side with a
short fin that ripples like a flag. It has eight arms and two long
tentacles; the tentacles retract completely into the body and extend as though
spring-loaded to capture prey. It has a beak, and discharges ink when agitated--in this case the useful pigment sepia. Quick movements are accomplished with jet power, generated by a siphon. It eats small crustaceans and fish and other cuttlefish.
The cuttlebone is the most well-known part of the cuttlefish. It functions as a swim bladder: the cuttlefish changes depth by injecting or pulling gas into/out of the
bone. The cuttlebone prevents the cuttlefish from venturing into deep
waters by imploding. It is rich in calcium and salt and makes a good supplement for a pet bird.
The cuttlefish has sophisticated eyes. The pupils are wavy and cross the eyes horizontally--like in a goat's eyes, only weirder. The pupils bend incoming light to reveal transparent prey.
Cuttlefish have short lives, as cephalopods do. One to two years.
Mating cycles occur
year-round, spiking in March and June. Males deposit sperm with a hectocotylized arm, an arm specialized for mating. Eggs are large, about 6-9 millimeters, and are stored in the female's oviduct until distribution in clumps on the sea floor. Typically the eggs are tinted with sepia to blend with the sand. After roughly two months the young hatch with a supply of yolk
that serves them until they are able to secure prey, which is soon. Cuttlefish
hatchlings are more formidable than those of squid or octopus and are able to overpower small crustaceans almost immediately.
The cuttlefish's blood is greenish blue, like an alien. The color results from the pigment hemocyanin, which carries oxygen; in red-blooded animals oxygen is carried by hemoglobin.
The cuttlefish is called the chameleon
of the sea, which is generous to chameleons. In cuttlefish, color changes
are accomplished instantly by small structures in the skin called chromatophores, leucophores and iridophores--tiny bags of ink that contract and expand to create color like pixels
on a screen. They come in colors
red, yellow, brown, and black. A layer of chromatophores is above a
layer of iridophores; iridophores make a layer above leucophores.
Each square millimeter of skin can contain 200 bags of pigment. Colors are used to hide from predators and to communicate with
other cuttlefish; basic color is a mottled black or brown. Cuttlefish can also change their skin's texture.
Cuttlefish are kept as pets primarily in the UK. They're said to be very much like cats, in that they rest, pounce, and beg for food even when they're fat. Cuttlefish imported to the US as pets are typically the poor-traveling Balinese Sepia bandensis, which arrive four inches long and have weeks to live.
Cuttlefish are demanding creatures to keep.
The saltiness of their water must be proportional to their
body size, and their tanks need to be cleaned every time they ink. They also cannot handle abrupt changes in light.
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