Lottia digitalis lobed and irregular. The shell characteristics are very variable. The color is usually brown or dark olive with white patches. The range of "L. digitalis" extends from northern Alaska to northern Mexico. It is a common species and is found among acorn barnacles on vertical rock faces in high to mid-intertidal zones, on both exposed and sheltered coasts. In California, young limpets, up to ten millimetres in diameter, often live on the opercular plates of gooseneck barnacles, "Pollicipes polymerus" and on mussel shells. In both cases, the colouring varies from that of the rock-based form and provides camouflage. At Mission
Plant physiology plants produce a vast array of chemical compounds with unique properties which they use to cope with their environment. Pigments are used by plants to absorb or detect light, and are extracted by humans for use in dyes. Other plant products may be used for the manufacture of commercially important rubber or biofuel. Perhaps the most celebrated compounds from plants are those with pharmacological activity, such as salicylic acid from which aspirin is made, morphine, and digoxin. Drug companies spend billions of dollars each year researching plant compounds for potential medicinal benefits. Plants require some nutrients, such as carbon and