How do squids protect themselves from predators?
When hiding from predators doesn't do the trick, a squid has several other defense mechanisms at its disposal. It can startle an oncoming predator, physically attack it, move erratically to confuse it, play dead, flee, or, in the case of the deep-sea squid Octopoteuthis deletron, sever ties with a body part.
Octopuses use several different strategies to evade predators—they camouflage themselves by quickly changing their skin color, they make colorful displays or eject ink to startle or confuse potential predators, they squeeze into small crevices to escape, and they quickly propel themselves through water.
Squid have some unique adaptations. Some can change color, some use bioluminescence to create light, and some shoot ink to cloud the water and lose predators.
Both the arms and tentacles are equipped with powerful suckers that can function like suction cups. The suckers in some squids are transformed into sharp hooks to better grasp their prey, making squid a formidable underwater predator.
How do squid protect themselves from predators? By use of camouflage and squirting ink.
Gladius, or pen
The gladius is a rigid internal structure that supports the squid's body and runs through the upper part of the mantle, between the paired tail fin. It is made of chitin – a tough, protective, and semi-transparent substance, which is primarily a nitrogen-containing polysaccharide.
To catch its prey, the colossal squid lunges forward, using its giant fins for propulsion, and lowers its arms and tentacles. It then shoots out its two 2-metre-long tentacles to catch its victim. The rotating hooks on the end of its tentacle clubs latch on to the fish and stop it escaping.
Once prey is caught by the suckers and teeth on the feeding tentacles, the squid will rein it in and bring it towards its beak with its eight arms. The beak breaks the food down into smaller pieces, and the radula, a tongue-like organ covered in teeth, grinds it down further.
Some squid can change colors to help hide from danger. Many organisms use this form of defense, camouflaging their bodies to blend in with their surrounding environment. Squid, however, do so by expanding or contracting the pigment cells in their skin called chromatophores.
Squids rely on epigenetic mechanisms to survive environmental extremes and retreat into a state of suspended animation by slowing down their metabolic rate. They reduce the squid's oxygen requirements, turn off non-essential biological processes and sidestep damage from cold temperatures.