Symbiosis is the relationship between two or more organisms that are in close physical proximity and is generally beneficial to at least one of these organisms. If the relationship is beneficial to all the involved organisms, it is termed mutualism. If only one organism gets the benefit, but the other (or others) do not get adversely affected, it is termed as commensalism. In parasitism, on the other hand, one of the species gains at the expense of the other. Some examples of symbiosis are:
- Ticks and dogs: These have a parasitic relationship with the tick gaining at the expense of the dog. The tick enters the skin of the dog and drinks its blood, obtaining nutrients from the dog, while the dog loses the blood.
- Egrets and cattle: Egrets are birds that are often found very close to cattle. Sometimes, they are found perched on top of the cattle. Egrets eat the parasites from the cattle's skin and also the grasshoppers as the cattle walk through the field. In this way, egrets get food, while the cattle gets rid of parasites and grasshoppers (which bother and bite them). Thus, their symbiotic relationship can be termed as mutualistic.
- Mites and wasps: mites use wasps for transportation, while also acting as their protectors from parasitic wasps, thus exhibiting mutualism.
Hope this helps.