40 Fun Facts About Cuttlefish

How many separate hearts pump the blue-green blood of a cuttlefish around its body?

Three hearts share the work: two push blood through the gills and one sends it around the rest of the body.

Which reddish-brown color, linked with antique photographs, takes its name from the Greek word for cuttlefish?

Sepia began as a brown pigment taken from the ink sac of the cuttlefish, and artists drew with it until the 19th century.

Thanks to their most famous talent, cuttlefish are sometimes nicknamed which reptiles of the sea?

Chameleons of the sea is the nickname, because cuttlefish can change skin color within a second to hide, signal one another or startle predators.

Cuttlefish mothers coat their egg clusters in ink, making them look very much like which fruit?

Grapes are what the inky clusters resemble, and each egg hatches into a miniature version of the adult.

To test depth perception, scientists fitted cuttlefish with which tiny accessory before screening films of shrimp?

3D glasses with red and blue filters showed that cuttlefish judge distance with both eyes, striking at the place where the shrimp seemed to be.

Cuttlebone, the chalky internal shell of a cuttlefish, is sold in pet shops as a calcium supplement for which pets?

Caged birds such as parrots peck at it for calcium, and cuttlebone often washes up on beaches after a cuttlefish dies.

Despite the name, cuttlefish are not fish; they belong to which group of animals?

Mollusks include cuttlefish alongside snails and clams, even though the cuttlefish keeps its shell inside the body, as the cuttlebone.

Not counting its pair of longer feeding tentacles, how many arms does a cuttlefish have around its mouth?

Eight arms hold and handle the prey once the pair of longer tentacles has grasped it.

Cuttlefish in a lab showed self-control by passing an adapted version of which famous experiment devised for children?

Marshmallow test results put cuttlefish alongside chimpanzees and crows: they held out for 50 to 130 seconds.

Besides color, which feature of their skin can cuttlefish change, using bands of circular muscle, to mimic rocks?

Texture changes when the muscles contract and push fluid up into little spikes, bumps or flat blades.

Which metal in the oxygen-carrying protein hemocyanin gives cuttlefish blood its unusual blue-green tint?

Copper does the job that iron does in human blood, but it carries less oxygen, so cuttlefish blood has to flow faster.

The largest cuttlefish species, up to a meter long with tentacles outstretched, is native to which country's waters?

Australia is home to the giant cuttlefish, which ranges around the southern half of the coast, from Brisbane to Shark Bay and down to Tasmania.

In northeast Italy, cuttlefish ink is famously used to turn which classic dish jet black?

Risotto al nero is the northeast Italian classic, and across the Adriatic in Croatia the same dish is called crni rižot.

Ground-up cuttlebone, once a goldsmith's polishing powder, was also added to which everyday bathroom product?

Toothpaste once contained powdered cuttlebone, which was also taken as an antacid.

By changing the mix of gas and liquid held in its chambered cuttlebone, a cuttlefish controls what?

Buoyancy is tuned through an organ on the underside of the cuttlebone, which fills its chambers with gas or liquid.

A cuttlefish can release a blob of ink about its own size, called a pseudomorph, which serves as what?

A decoy of ink keeps a predator busy while the cuttlefish swims away, and a wider smoke screen can hide the escape too.

Cuttlefish rank among the most intelligent invertebrates, yet most species typically live for only how long?

One to two years is all most cuttlefish get, and many die soon after they reproduce.

Which hard mouthpart, hidden at the center of its arms, does a cuttlefish use to break into armored prey?

Beak bites also deliver venom, which nearly all cephalopods can produce to help kill their prey.

In Spencer Gulf, which marine mammals have been seen removing the ink and cuttlebone from cuttlefish before eating them?

Dolphins there, Indo-Pacific bottlenoses, use a specialized technique to clean each cuttlefish before swallowing it.

A courting male cuttlefish can show mating colors on one side of his body while the other side imitates what?

A female pattern on the side facing a rival stops him from interfering, while the courtship display carries on unseen.

Which shape describes the smoothly curving pupil in the eye of a cuttlefish?

W-shaped pupils sit in eyes that focus by sliding the whole lens back and forth, rather than reshaping it as mammals do.

Cuttlefish cannot see color, yet their eyes can perceive which property of light that sharpens contrast?

Polarization vision helps cuttlefish hunt silvery fish, whose scales give them away by polarizing light.

Which dark pigment is the main constituent of cuttlefish ink, alongside mucus?

Melanin may do more than hide a cuttlefish: computer simulations suggest it overwhelms the scent receptors of sharks.

When startled, a cuttlefish jets away by squirting water through which organ, often inking as it goes?

Siphon jets are for emergencies; day to day, a cuttlefish cruises by rippling the fins around its mantle.

Young cuttlefish may prefer to hunt whichever prey they first watched from where?

Inside the egg, embryos shown crabs went on to hunt crabs after hatching, though hatchlings normally prefer shrimp.

What happens to the cuttlebone of a cuttlefish that dives deeper than a few hundred meters?

It implodes somewhere between 200 and 600 meters down, which is why most cuttlefish keep to shallow seafloors.

Resting cuttlefish twitch their arms and flash skin patterns in a state resembling which human phenomenon?

REM sleep is the closest match: the common cuttlefish shows predictable bursts of rapid eye movement while it rests.

In the Greco-Roman world, the brown fluid that cuttlefish squirt was commonly put to which everyday use?

Writing was its common use in antiquity, when the fluid served as ink; today artificial dyes have mostly replaced the natural pigment.

Rival male cuttlefish face off using an intense striped display, considered an honest signal, named after which animal?

Zebra stripes announce a contest, and a male that means to attack also darkens his face.

Which shelled sea animal is a cephalopod, making it a relative of cuttlefish, squid and octopuses?

Nautilus species are the only living cephalopods whose shell is still on the outside.

Which pigment-filled sacs in cuttlefish skin are stretched open by tiny muscles to reveal yellow, red or brown?

Chromatophores are under direct neural control, which is why a cuttlefish can redraw its whole pattern almost instantly.

Cuttlebone is more than 90 percent empty space by volume, with walls made mostly of which mineral?

Aragonite is brittle, yet the wavy pillars within cuttlebone stop cracks from spreading, a trick engineers copy in ceramic foams.

The earliest known cuttlefish fossils, found in the Netherlands, date from the end of which geological period?

Cretaceous rocks of the Maastricht Formation hold Ceratisepia, the earliest cuttlefish in the fossil record.

Hunting cuttlefish send dark mottled waves down their bodies in a display researchers named after what?

A passing cloud is the name for the rippling display, which the common cuttlefish shows mainly while it hunts.

The small, vividly colored flamboyant cuttlefish is known for moving across the seafloor in which unusual way?

Walking on its lower arms suits this species, because its cuttlebone is too small to keep it afloat for long.

Because the optic nerve sits behind the retina, the eye of a cuttlefish lacks which flaw found in human eyes?

A blind spot never forms, because no nerve fibers have to pass through the light-sensing layer on their way out of the eye.

Young broadclub cuttlefish hide among coral rubble by imitating what, right down to scattered black spots?

Mangrove leaves are copied in posture as well as color, complete with a stem and ribs.

Hot butter cuttlefish, batter-fried and tossed with chili flakes, is a popular starter in which island country?

Sri Lanka serves it nationwide alongside drinks, while East Asia prefers its cuttlefish dried and shredded as a snack.

Which region's coasts have no cuttlefish at all, perhaps because the North Atlantic was too cold for them to cross?

The Americas have no cuttlefish on any coast, though the animals thrive off Europe, Africa and Asia.

Cuttlefish belong to the class Cephalopoda, a name built from Greek words with which literal meaning?

Head-feet fits the layout: a prominent head ringed by arms that evolved from the foot of the animal's ancestors.