• Male and female frogs can be distinguished by characters like size (females are usually larger), vocal sacs, and nuptial pads in males.

• Male frogs develop nuptial (copulatory) pads during the breeding season on the first digit (thumb) to hold females during amplexus.

• In male frogs, the urinogenital ducts (carrying both urine and sperm) open into the cloaca through a common opening, not separately.

• Frogs excrete urea as the main nitrogenous waste, hence they are ureotelic.

• Frogs do not have an external ear structure; only the tympanum is externally visible.