Octopuses have reverted to more benthic habitats. Their bodies are globular and bag-like without fins. They usually occupy a den from which they emerge to hunt for food. They can swim by jet propulsion with arms trailing but more frequently crawl over the seafloor. Some deep-living octopuses, e.g. Tremoctopus violaceous, have webbed umbrella-like arms and swim with jellyfish-like pulsations as well as by water jet.