In this given scenario, large cargo ships regularly move species around the ocean in their bulk tanks. When people sail the sea, marine organisms tag along and can invade and disrupt ecosystems. If a highly effective predator such as sperm whales or Tuna, who hunt by using eyesight and speed, were transported on one of these large ships and introduced into a region where squids live, this would destroy the squid's ecosystem and kill off or push out many of these organisms. These new predators will act as selective forces by changing the environment of the squids causing it to be a more dangerous place to inhabit.
As I have learned from biology lab, survival of the fittest for any species is directly related to the amount of food sources in the area in which the organism lives, the number of predators, and the stability of the environment. Luckily, in this particular circumstance, the squid's skin is covered in chromatophores that help is change colors very quickly to match their surroundings becoming camouflaged. Squids also have a very large muscular foot of the mollusk ancestor that has become a set of tentacles extending from their head that help them grasp food and steer as it swims. Male squids have one extra long tentacle, which is their penis, used to reach into the females vagina located behind her head. .
Squids have other characteristic that enables them to survive. Squids swim with a jet like locomotion, propelling through the water, backwards. A large eye on both sides of their head enables them to watch their back literally, as well as navigate efficiently looking back at surroundings. The ink sac is located inside the mantle, which squids use as a treat to confuse the sperm whale or another predator and make their quick escape. Lastly, squids feed on creatures like plankton, small fish, and shrimp, using their hard beaks made of chitin. These pre-existing variations in squids, who are members of the Mollusca class Cephalopod, will help them to better adapt and survive with this new predator-filled environment.