Symbiotic relationship (+ +) – mutually beneficial cohabitation of organisms of different species.
Such relationships are characteristic of species with very different needs, where they successfully complement each other. There are several types of such relationships: protocooperation, mutualism and symbiosis proper.
Protocooperation is a relationship that is beneficial for both organisms, in which coexistence is not necessary.
In these cases, there is no close connection between a specific pair of partners. An example of such a relationship is the relationship between flowering plants and their pollinators. Most insect pollinated flowering plants cannot form seeds without the participation of pollinators – insects, birds, mammals. Pollinators, on the other hand, are interested in nectar and pollen for food. Moreover, in many cases, neither the plant nor the pollinator is important about the specific type of partner.
Example: pollination of different plants by bees.
Example: the spread of seeds of some forest plants by ants.
Mutualism is a relationship in which there is a stable mutually beneficial cohabitation of two organisms of different species.
Mutualism is very widespread in nature. Unlike the previous type of interaction (protocooperation), in mutualism there is a strong connection between a specific pollinator and a specific plant species, surprisingly subtle and perfect mutual adaptations of the flower and the animal that pollinates it are formed.
Example: clover and bumblebee. Only bumblebees with their long proboscis can pollinate clover flowers, inaccessible to other pollinators.
Example: nutcracker and cedar pine. The bird eats cedar pine nuts and spreads its seeds.
Example: a jay that spreads the acorns of an oak makes supplies for the winter, buries the acorns. Not all of the bird’s own caches are subsequently found, the seeds germinate; the jay thereby unwittingly helps the oak to spread.
Example: sea anemone and hermit crab. The anemones settle on the shell in which the hermit crab lives, and with its tentacles equipped with stinging cells, creates additional protection for it. The hermit crab drags the anemone from place to place, thereby increasing its hunting territory; in addition, the anemones can also consume the leftovers from the hermit crab meal.
Actually symbiosis is an obligatory mutually beneficial cohabitation of two types.
Example: The lichen thallus is a complex of interconnected fungal hyphae and algae cells. Due to the fact that the fungus and algae provide each other with all the necessary nutrients, lichens are little dependent on environmental conditions and are able to live where other organisms cannot survive: on rocks, high in the mountains, in the desert.