ities that help them deal with their predators (which range anything from large fish to sperm whales). Their lack of an external shell allows them to squeeze into very tight places, enabling them to conveniently and easily hide from their enemies. When confronted with a dangerous animal away from hiding places, however, squids seem to have a disadvantage when compared to other mollusks with external shells. If attacked, they have no exterior protection. To counter this potential crisis, they have adapted a number of tactics.First, they are capable of temporarily altering the color of their skin, in effect camouflaging themselves. They can shift their appearance from a deep brown color, to a white, or almost transparent quality. Along with this, they are able to slightly change the texture of their skin. This form of camouflage allows the squid to take the form of rocks, seaweed, or other ocean-dwelling objects.If a hazardous foe is not fooled by camouflage, the squid can release an ink cloud. The ink cloud has a number of helpful characteristics that can ward off enemies. The cloud initially causes the nearby water to become dark and cloudy, reducing the enemy’s visibility and allowing the squid to escape from danger. Some deep-sea squids contain bacteria in their ink so that the cloud glows, and scares away harmful rivals. Also, the cloud usually takes on the form of a shape resembling a squid, providing a distraction from the real one. Another quality of the ink is that it can completely reduce the opponent’s ability to smell—one of the key components for searching for prey found in many predators.Squids are usually seen swimming in large schools. They are capable of great bursts of speed—up to 23 mph, by utilizing a highly advanced form of water-jet propulsion. Of the 375 known species, they can range in size from 8 inches to 60 feet long. It is the largest of all aquatic invertebrates. Depending...
