Definitions

1. noun

An organism that obtains food from another organism, typically one that provides it with shelter or protection, often in a mutually beneficial relationship.

“In the coral reef ecosystem, the sea anemone and the clownfish have a commensalist relationship, where the fish receives protection from predators in the anemone’s stinging tentacles.”

2. noun

An animal that obtains food from a host without causing it significant harm.

“The tick is a commensalist parasite that feeds on the blood of its host, usually a large mammal.”