Introduction- Organism- Carcharodon Carcharias, also known as the Great White Shark. The Great White Shark is the largest predatory shark and is the most well-known and feared shark. It is gray, bluish and white. The biggest Great White Shark can reach up to 22 feet and weigh 5000 pounds. The classification of the Great White Shark is Chondrichthyes. It belongs to the Animal Kingdom. Its' Phylum is Chordate. Its' order is lamniformes. The family it belongs to is Lamidae. Its' Genus is carcharodon. Finally its' species is C. Carcharias. It lives in the outskirts of shore waters. Sometimes going to the deep ocean and are sometimes found 1000 meters or even more. The Great White Shark evolved 455 or 425 million years ago.
Morphological and Molecular Evidence: The closest relatives to the Great White Shark are skates, stingrays, and chimaeras. Skates are rounded to diamond-shaped with large pectoral fins. Stingrays and Great White Sharks both have gills. Stingrays are distinguished from sharks by a flattened body. Chimaeras is the ghost shark. They have cartilaginous like sharks and rays. Originally paleontologists believed the Great White Shark descended from the 50 foot megalogdon because of the teeth structure. A new shark fossil shows hybrid teeth of the mako shark ancestor and the Great White.
Homologous Structures: Bats, dolphins, and sea lions are examples that have homologous structures. Bats have wings which they use their wings to flies. Dolphins have pectoral fins that use them for body heat while Great White sharks use pectoral fins to turn and signal. Sea lions use flippers to swim around and to stand on. Homologous structure are organs or bones that are in different animals that look a like but serve a different purpose. The structure evolved to be used differently.
Vestigial Structures are things that the organism still have but don't use it or is not functional. Great White Shark have three vestigial structures. First is the ribs which are used to protect the organs. They are too heavy as bones but as cartilage they sharks are not weighed down. Claspers are in reproduction. Sharks have two of them but only one of them is used. Lastly, the first gill slit which is behind the eye. These structures are still functional in other animals therefore in the current organism they evolved to live with out using them.
Transitional Fossils are any fossilized remains that can be seen in the ancestor group and the current group. Great White Shark only has one transitional fossil that can be seen. The third upper tooth in their dentition of the Great White Shark is a characteristic that is seen in all mako shark dentition. Therefore, the Great White Shark is descended from the Extinct Mako Shark.
Comparative Embryology: The comparison between sting rays and the Great White Shark embryo development are similar. Both have eggs that hatch inside them. For sting rays, the pups feed off a placenta like structure. Great white sharks pups do not. Sting rays evolved away from sharks.