A relationship between two organisms in which one organism benefits and the other is unharmed.

Two organisms that are so similar they can interbreed in nature and produce fertile offspring.

Silverfish live and hunt with army ants. They share the prey. They neither help nor harm the ants.

A cuckoo and a warbler are both birds. A cuckoo will find the nest of warbler instead of building her own, and she harms the warbler by knocking a warbler egg out of nest and laying her own. When the warbler mother returns, she isn’t aware of the switch. The warbler will then raise the baby cuckoo bird instead of her own baby. Which term best describes this relationship?

Barnacles are sea creatures that create a home by attaching themselves to whales. The whales are unaffected by the barnacles. Which term best describes this symbiotic relationship?

Ostriches and gazelles are two animals that live in Africa. They graze for food near each other because they help each other spot predators. The gazelle has excellent eyesight, but poor hearing, and the ostrich has excellent hearing, but poor eyesight. These two animals will alert one another when danger is near. Which term best describes this relationship?