The relationship between the hermit crabs and the snails is A.commensalism
Why? Commensalism refers to a relationship where one organism benefits from the other without affecting it. In this case, the hermit crab benefits from the snails, via the latter's discarded shells. The crab's use of the snails' shells has no impact on the snails.
The medulla oblongata detects the levels of oxygen and carbon dioxide concentrations and signals the muscles in the heart, the lungs and diaphragm to increase or decrease thebreathing. The pons controls the speed of inhalation and exhalation orrespiration rate depending on the need of the body.
Bacteria mostly act as "Decomposer" 'cause they decompose the dead & decaying matter, back into inorganic materials.
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