What is the most poisonous sea animal that lives in Guam?

The most poisonous sea animal that lives in Guam is the blue-ringed octopus. This small, brightly colored octopus is found in the shallow waters of the Pacific and Indian Oceans. It has a powerful venom that can cause paralysis and death. The blue-ringed octopus is not aggressive, but it will defend itself if it is threatened.