Other
The Sea Slug Forum: Symbiosis and Commensalism
Question and answer site that contains a discussion of commensalism as it pertains to sea slugs. Nice photographs of aquatic commensalistic relationships.
American University
American University: Sea Cucumber Loss in the Galapagos
Describes the human interest in sea cucumbers, and the ecological influence of sea cucumbers on the Galapagos Islands.
A-Z Animals
A Z Animals: Animal Facts: Sea Slug (Holothuroidea)
Provides photographs and a fact card about the sea slug, also known as the sea cucumber. Discusses where they live, diet, predators, physical features, the different species, reproduction, and their value to humans.