Amphibians have gills when they are young or they breathe through their skin. Adult amphibians either have lungs or continue to breathe through their skin.Amphibians have three ways of breathing. The first is with gills, seen on tadpoles and salamanders that do not leave the water. The second isâ¦.
Embryology is the branch of developmental biology that studies the beginning and early growth of sexually reproducing organisms. This life science specialty focuses primarily on embryogenesis (the formation and development of embryos). In humans, the term embryo is traditionally reserved for the first two months of development. After that point, the term âembryoâ is replaced by the term âfetus,â which then applies until birth. At the beginning of the individualâs development, the entity is a single cell. After two months, it has limbs, distinct fingers and toes, internal development, and countless cells.
In the context of biology, homology is the existence of shared ancestry between a pair of structures, or genes, in different species. A common example of homologous structures in evolutionary biology are the wings of bats and the arms of primates. Evolutionary theory explains the existence of homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.