Pavo is a bird, Ornithorhynchus is a mammal, Salamandra is an amphibian and Hippocampus is a bony fish. Reptiles, birds, land snails and insects excrete nitrogenous wastes as uric acid in the form of pellet-or paste with a minimum loss of water. Such animals are called uricotelic animals. Many bony fishes, aquatic amphibians and aquatic insects are ammonotelic in nature.
Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals.