1. A particular species of a unicellular organism inhabits the intestines of termites, where the unicellular organisms are protected from predators. Wood that is ingested by the termites is digested by the unicellular organisms, forming food for the termites. Mutualism

2. Mistletoe grows on trees. It sends its roots into the tree and uses the nutrients that could otherwise be used by the tree. Therefore, the tree does not get to use all the nutrients. Parasitism

3. Lichen species are made up of a fungus that contains either a bacterium or an alga. The fungus protects the bacterium or alga, and the bacterium or alga provides food for the fungus. Mutualism

4. An American Robin benefits by building its nest in a Red Maple tree. The tree is unaffected. Commensalism

5. The sea fan works as a camouflage for the seahorse, and the sea horse benefits because of the deception from the predators. Commensalism

6. Some ant species use excess plant sap for their own nutrition. These ants will find a colony of aphids and milk the waste plant sap from the cornicles. In return the ants protect the aphids from predators and parasites. Mutualism

7. Barnacles live by using long, feathering appendages to sweep the surrounding water for small, free-floating organisms. The critical resource for barnacles is a place to stay. Barnacles can attach to the surfaces of whales, as well as rocks, ships, and shells. They do not harm the surface to which they attach. Commensalism

8. The honey bee gets to eat the pollen from the flower. The dandelion uses the bee to spread its pollen to another flower. Mutualism

9. The tick gets food from the deer without killing it. The deer is harmed by losing blood to the tick, and possibly by getting an infected wound. Parasitism

10. Birds and mammals eat berries and fruit off of plants in the wild. The birds and mammals derive a food benefit by eating the berries and fruits. The plant has its seeds dispersed by the animals. Mutualism

11. Many species of moss or algae may live on the bark of a tree. The tree is completely unaffected and the moss or algae has a place to live. Commensalism

12. Female mosquitoes ingest blood from humans and mammals for the protein to feed their larva. The saliva of the mosquito causes the skin to become irritated and itchy. Parasitism

13. Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers get food and the beasts get pest control. Mutualism

14. Commensalism A few species of pseudo-scorpions disperse by concealing themselves under the wing covers of large beetles. The pseudo- scorpions gain the advantage of being dispersed over wide areas while simultaneously being protected from predators. The beetle is, presumably, unaffected by the presence of the hitchhikers.

15. Hookworms infect humans by residing in the small intestine and feeds off of the digested food in the small intestines. As the hookworm grows larger, the human slowly starves to death. Parasitism

16. Lice (small insects that live imbedded in the hair of some animals) feed on the blood of mammals. Parasitism

17. Ladybugs live on plants, eating the aphids and benefiting by getting food, while the plant benefits by being rid of the aphids. Mutualism

18. In Texas, cattle egrets (large white birds) are often found near cattle. They can also be seen feeding on insects that the cattle stir up in the grass as they walk. Commensalism

19. A flea bites a dog drinking its blood supply. The dog gets small bumps on its skin causing it to itch. Parasitism

20. Spider crabs live in shallow areas of the ocean floor, and greenish- brown algae lives on the crabs' backs, making the crabs blend in with their environment, and unnoticeable to predators. The algae get a good place to live, and the crab gets camouflage. Mutualism

21. Heartworm, whose adults reside in the right side of the heart, in dogs, feed off of the blood supply. As the worm grows larger, the dog’s heart is unable to pump enough blood to the rest of the body to live. Parasitism

22. The cleaner fish remove parasitic fish and diseased tissue from larger fish’s scales, gills, or mouths. The cleaner fish get a meal and the larger fish get cleaned. Mutualism