Symbiosis

Parasitism

A symbiotic association in which one organism benefits while the other is harmed is called parasitism (PAR uh SIT IZ uhm). The organism that benefits is called the parasite. The organism that is harmed is called the host. The parasite gets nourishment from its host while the host is weakened. Sometimes, a host dies. Parasites, such as ticks, live outside the host's body. Other parasites, such as tapeworms, live inside the host's body.

Mutualism

A symbiotic relationship in which both organisms benefit is called mutualism (MYOO choo uhl IZ uhm). For example, you and a species of bacteria that lives in your intestines benefit each other! The bacteria get food from you, and you get vitamins that the bacteria produce.

Commensalism

A symbiotic relationship in which one organism benefits and the other is unaffected is called commensalism. One example of commensalism is the relationship between sharks and smaller fish called remoras. Remoras attach to a sharks body. Remoras "hitch a ride" and feed on scraps of food left by sharks. The remoras benefit from this relationship, while sharks are unaffected.

Ex-Parasitism

An example of a host is a bright green caterpillar called a tomato hornworm. A female wasp lays tiny eggs on the caterpillar. When the eggs hatch, each young wasp will burrow into the caterpillar's body. The young wasps will actually eat the caterpillar alive! In a short time, the caterpillar will be almost completely eaten and will die. When that happens, the adult wasps will fly away. In this example of parasitism, the host dies. Most parasites, however, do not kill their hosts. Most parasites don't kill their hosts because parasites depend on their hosts. If a parasite were to kill its host, the parasite would have to find a new host.

Ex-Commensalism

Mutualism also occurs between some corals and the algae living inside those corals. In this relationship, a coral receives the extra food that the algae make by photosynthesis. In turn, these algae also receive a place to live. These algae also receive some nutrients from the coral. Both organisms benefit from this relationship.

Ex-Mutualism

Mutualism also occurs between some corals and the algae living inside those corals. In this relationship, a coral receives the extra food that the algae make by photosynthesis. In turn, these algae also receive a place to live. These algae also receive some nutrients from the coral. Both organisms benefit from this relationship.

Symbiosis

Some species have very close interactions with other species. Symbiosis is a close, long-term association between two or more species. The individuals in a symbiotic relationship can benefit from, be unaffected by, or be harmed by the relationship. Often, one species lives in or on the other species. The thousands of symbiotic relationships in nature are often classified into three groups: mutualism, commensalism, and parasitism.