Question

The models show the life cycles of a fish and a frog. Explain why these life cycles show characteristics common to their class of vertebrates.

Answer 1

Fish are able to breathe underwater at birth because they have gills. The fish life cycle shows that the newly hatched larva is able to survive underwater. The fish also show paired fins, which is a characteristic of fish. The frog life cycle shows the organism going through metamorphosis, changing from an aquatic larva to a terrestrial adult. For this transition to happen, the larva needs to develop lungs. This metamorphosis is common in amphibians.

Answer 2

This is because all land vertebrates share a common ancestor. All land vertebrates emanated from evolution form the oceans and seas from a group categorized as Sacropterygii. Therefore during the early phylotypic stages of embryonic development, the embryos of all land vertebrates look alike morphologically. It is believed it is during this stage that the basic plan of the body takes shape before it begins to diverge.