An organism is found to have a three-chambered heart, moist skin for cutaneous respiration, and requires water for reproduction. Its larvae are aquatic, while adults can live on land. However, it lacks an amniotic egg. This organism belongs to which of the following groups?
Correct: C
The combination of a three-chambered heart (two atria, one ventricle), moist skin for cutaneous respiration, dependence on water for reproduction (external fertilization, larval development in water), and an aquatic larval stage with terrestrial adults are all characteristic features of Amphibia (frogs, toads, salamanders). The absence of an amniotic egg is also a key feature, as amniotes (Reptilia, Aves, Mammalia) have evolved this adaptation for fully terrestrial reproduction. Reptiles have a three- or four-chambered heart, dry scaly skin, and lay amniotic eggs. Aves and Pisces do not fit this description.