The use of natural sponges by Bottle-Nosed dolphins serves as protective device for their delicate snouts. The sponges are firm enough to
disturb the sand and seaweed on the ocean floor as a device to expose fish, but it is gentile and light enough to be easily manuvered by the snout.
However, when examining the adaptive value of tool use, the big question is not so much the sponge use itself, but the spread of information on
how to use the sponge. The development of cultural  capabilities in bottle nosed dolphins is linked back to the natural selection that emphasized
the importance of social behavior in order to succeede in navigating through a large and complex environment. There are no known chemicals,
genes or hormones that have been  specifically linked back to sponge use in dolphins, however, scientists do theorize that there may be a
 "gene-culture coevolution among cetaceans." (Randall and Whitehead 2001) Evidence for this is found in cetaceans' highly structured dialectic
vocalizations. Theory states that underwater environments are subject to rapid change in food densities, temperature and habitat structure.
Becuase of this complex environmental scenario, the ability to coordinate behavior and information transfers in an attempt to give stability
 to an intense and convoluted social structure may have selected towards evolution for a larger brain adept at social learning and transmission.