Answer:
Carbon dioxide dissolve readily in sea water hence makes it high in carbonic acid concentration. The fresh water will dilute the concentration of carbonic acid thus preventing the crab from being exposed to high concentrations which can dissolve its shell.
<em>Hope</em><em> this</em><em> helps</em><em> </em><em>!</em>
Answer: Sensory mechanisms are responsible for detecting the external stimuli present in the environment.
Explanation:
The sensory mechanisms help people to observe things around them through eyes, they can hear the sounds through their ears, they can feel the insect creeping on their skin by touch sensory mechanism, they can taste food which they cook through taste or gustatory receptors present on tongue and other parts of mouth cavity.