Dolphins are often regarded as one of Earth's most intelligent animals, though it is hard to say just how intelligent dolphins areas comparisons of species' relative intelligence are complicated by differences in sensory apparatus, response modes, and nature of cognition. Furthermore, the difficulty and expense of doing experimental work with large aquatics means that some tests which could yield meaningful results still have not been carried out, or have been carried outwith inadequate sample size and methodology. Dolphin behavior has been studied extensively by humans however, both in captivity and in the wild" -- Reference Wikipedia.org back to 177)
