As with other living organisms, squids exhibit an individual purpose of maintenance, survival, and reproduction, and a purpose for the system as a whole. In this latter aspect, squids play a key role in food chains. They prey on fish, crustaceans, and other mollusks, and in turn are preyed on by fish and aquatic mammals, such as whales. Even the giant squid is prey to sperm whales.
In terms of contribution to humans, they have been a source of food for thousands of years, and are today a popular food item. Their protein is considered to be low calorie and with healthy unsaturated fatty acids. Having a highly developed nervous system, and ability to remember, they are also valuable experimental animals in biomedical and neurophysiology research.
Beyond these values, squids have aesthetic value, whether in marine aquariums or as a focal point in movies or other media, touching upon people's imagination and ability to experience beauty.