Typically octopus and squid produce black
Octopuses do expel ink from their siphons, which are also the openings through which they shoot water (for swimming) and bodily waste. So although not exactly flatulence, octopuses' ink—used to confuse predators—does emerge from the opening that could be considered its anus.
Cephalopod ink is a dark-coloured or luminous ink released into water by most species of cephalopod, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the Cirrina (deep-sea octopuses), are able to release ink to confuse predators.
Cephalopods use their ink to scare or distract predators so they can escape before being seen (or eaten). The ink is ejected from the ink sac within the cephalopod's body. The ink is made of melanin and mucus. Melanin is also in humans and is responsible for the color of our hair and skin.
Typically octopus and squid produce black ink, but ink can also be brown, reddish, or even a dark blue. Octopus and Squid use their ink as a defense mechanism to escape from prey. When feeling threatened, they can release large amounts of ink into the water using their siphon.
Perhaps the ink interferes with normal respiration, or other physiological activities, of the octopus. Squid and octopus inks are often consumed by humans in recipes for these species and, of course, by their natural predators. There is apparently no harmful effect in doing this."
Cephalopod ink is composed of secretions from two glands. The ink sac with its ink gland produces a black ink containing melanin, and most of what is known about cephalopod ink comes from studying it. A second organ, the funnel organ, is a mucus-producing gland that is much more poorly studied.
Both octopuses and squids have ink sacs that they use to release ink as a defense mechanism, and they contain melanin. However, octopus ink is usually thicker and more toxic.
The ink from cephalopods is not toxic, contrary to popular belief. However, squids and octopuses do have venom glands completely unrelated and separate from the ink sacs. For more information about octopus ink, watch the video below!
Squid ink, also called cephalopod ink, has been used in traditional medicine for centuries. It's also used as a pigment, writing ink, dye, and black food coloring.
Octopuses and squids will squirt ink when they sense danger approaching them. In fact, we've tested the defensive power of the ink. The squid squirts the ink, which not only allows it to escape, but (in some octopus species) it also acts like a visual alarm cue for other members of the same species.
If a predator gets too close octopuses can escape quickly, shooting themselves forward by expelling water from a muscular tube called a siphon. Octopuses can also release a cloud of black ink, which obscures them and dulls an encroacher's sense of smell.
Octopuses eat crabs, mussels and fish, using venomous saliva to kill or paralyse their prey. Despite their venom, most octopus species aren't dangerous to humans.
They hunt through the day eating invertebrates and wounded fish by catching them with its arms and biting them with its tough beak. The octopus kills by delivering the poison in its saliva. In order to escape predators an octopus can squirt black ink into the water.
Octopus feel pain and they feel themselves being chopped up and eaten alive. In an article published by Vice they interviewed Jennifer Mather, PhD, an expert in the behaviour of octopus and squid at the University of Lethbridge in Alberta. “It's probable that the octopus's reaction to pain is similar to a vertebrate.
Octopuses may look cute, but beneath their tentacles lies a deadly weapon — their venom. Many octopuses use venomous saliva to paralyze and incapacitate their prey, making them easy pickings for a tasty meal. This venom is contained within specialized salivary glands, similar to human saliva glands.
But the bright blue coloring says as boldly as it can: don't touch, I'm toxic. Blue-ringed octopuses can kill humans by biting and injecting venom. They bite when they feel threatened, and since we're so much bigger than they are, humans are certainly threatening!
While octopuses generally avoid humans, attacks have occasionally been verified. For example, a 240-centimeter (8-foot) Pacific octopus, said to be nearly perfectly camouflaged, approached a diver and attempted to wrap itself around the diver and his camera. Another diver recorded the encounter on video.
Octopuses are curious creatures and generally not aggressive toward people. But they will defend themselves if provoked and are capable of causing serious injury — as Bisceglia found out the hard way. "Wild animals are unpredictable and should be respected," Trautwein said.
Octopuses have blue blood, three hearts and a doughnut-shaped brain. But these aren't even the most unusual things about them! Known for their otherworldly look and remarkable intelligence, octopuses continue to reveal astonishing qualities, abilities and behaviour.
2) Octopuses have three hearts. Two of the hearts work exclusively to move blood beyond the animal's gills, while the third keeps circulation flowing for the organs.
"The dark color and some of the behaviors that go with it are associated with aggression, or at least approach," Scheel says. "The paler colors signify that the octopus is not going to stand its ground — that it's going to retreat or withdraw."