Squid are marine animals belonging to the class Cephalopoda, which also includes octopuses and cuttlefish. They have elongated bodies, large eyes, and eight arms, along with two longer tentacles. Squid are known for their ability to swim quickly by expelling water from their bodies, making them agile predators in the ocean. These creatures are found in various ocean habitats, from shallow coastal waters to the deep sea. Squid are important in the marine food web, serving as prey for larger animals like whales and sharks. They are also harvested by humans for food, often served in dishes like calamari.