Common snail The large group of animals called molluscs live on land and in both fresh and salt water. They constitute the phylum Mollusca, a major group of animals known to have as many as 100,000 living species and more than 50,000 fossil forms. Most molluscs, including snails, clams, oysters, and mussels, have shells. A [...]

Bed bug An organism that lives on or within another organism, called the host, and that gains its sustenance from the host organism is known as a parasite. Parasites occur among all the major groups of living things. There are parasitic fishes for example, the lamprey, which attaches itself to other fishes and sucks their [...]