Fig. . Sea anemone on hermit crab; Crocodile and bird COMMENSALISM (+, ): This defines the interaction in which two or more species are mutually associated in activities centering on food and one species at least, derives benefit from the association while the other associates are neither benefited nor harmed. The concept of commensalism has been broadened in recent years, to apply to coactions other than those centering on food such as cover, support, production, and locomotion.
Examples: • Barnacles attached to Whales travel thousands of miles collecting and filtering food from the moving water. The whales are not affected by the barnacles. MUTUALISM (+, +): It is the type of interaction where both species benefit from the interaction. Mutualism may be facultative when the species involved are capable of existence independent of one another, or obligate, when the relationship is imperative of the existence of one or both species.
Examples: • Certain bacteria in the caeca and intestine of herbivores aid in the digestion of cellulose. In return the host provides suitable environment for the growth of the bacteria. • The cross pollination of flowers by insects and birds seeking nectar and pollen which is of great importance in agriculture. • Small birds cleaning the teeth of crocodiles.
Here the birds gets food and the teeth of crocodile is cleaned. • The hermit crab carries along on its shell a Sea anemone (a sedentary coelenterate). The crab is protected from its enemies by the stinging cells of the anemone while the anemone gets its food ( Fig. .
). Table . Analysis of two species population interactions S. NO.
TYPES OF INTERACTION SPECIES SPECIES GENERAL NATURE OF INTERACTION EXAMPLES Amensalism -- The most powerful animal or large organisms inhibits the growth of other lower organisms Animals destroyed at the feet of elephants Mutualism + + Interaction favorable to both and obligatory Between crocodile and bird Commensalism + Population , the commensal benefits, while the host is not affected Sucker fish on shark Competition -- -- Direct inhibition of each species by