Octopods Nautilids Cuttlefishes Squids and Relatives: Cephalopoda

For hundreds of years, cephalopods have appeared in the art and literature of many human cultures around the world. Today they are sometimes featured in science fiction books and films as "sea monsters." Stories of giant squids washed up on the beach or captured in fishing nets sometimes dominate the news.

In 2000, about 4.0 million tons (3.6 million metric tons) of cephalopods were harvested, equaling about 4.2% of the world's total marine catch. Around the world, many people consider carefully prepared squids, cuttlefishes, and octopuses as tasty meals. Fishermen commonly use cephalopods as bait to catch very desirable species of marine fish for the dinner table.

Cephalopods are of unusual interest to scientists because they have well-developed brains and eyes, but they do not have backbones. They represent one of the most highly developed of all animals but are not related to fishes, birds, mammals, or other animals with backbones. The nerve tissues of giant squids have helped scientists to understand the basic functioning of the human nervous system. In fact, the study of cephalopod bodies is helping medical doctors to understand other aspects of human bodies.

Sometimes octopuses are considered pests because they enter traps set to capture mollusks such as whelks or lobsters. Once inside, they eat the catch. On rare occasions, cephalopods can be directly harmful to humans. Their bites, especially those of some octopuses, are painful to divers and sometimes deadly because of their toxic secretions. Schools of the large Humboldt squid have been known to attack scuba divers and fishermen who have fallen into the water.