What is the main characteristic that distinguishes the order Anura from Caudata in amphibians?

The distinguishing characteristic of the order Anura, which includes frogs and toads, is that its members lack tails in adulthood. This is a fundamental trait of Anura; as these amphibians undergo metamorphosis from their larval stage, they lose their tails. This adaptation plays a critical role in their life cycle and movement, allowing them to leap and swim effectively as adults.

In contrast, the order Caudata (which includes salamanders and newts) retains a tail throughout its life, a defining feature that sets it apart from Anura. This difference in tail presence and function is key to differentiating between these two orders of amphibians.

The other options do not accurately describe the distinctions between Anura and Caudata as they either misrepresent the characteristics of these orders or confuse aspects of their life cycles or anatomical features. Understanding these fundamental differences is crucial for classifying amphibians correctly within their taxonomic orders.