Sharks Essay

1732 Words 7 Pages
Sharks don’t fossilize well because they’re from the class of chondrichthyes meaning their skeletons are made of cartilage, a flexible connective tissue. This is one of the reasons why there is a disagreement over when the first shark first existed. However, shark teeth do fossilize well and sharks produce thousands of teeth in a lifetime. The oldest shark teeth date back to the Devonian Period about 400 million years ago and were found in Europe. Shark scales also fossilize well. Paleontologists can discover many important things from fossilized shark teeth and scales even though it doesn’t seem like much. Their discoveries include information about species, size and behavior. While it is controversial, some paleontologists believe that …show more content…
All of the mass extinctions resulted in a change in the environment. The worst mass extinction was 251 million years ago and 95% of species were killed from either comet impact or volcanic activity. Being a surviving species in a mass extinction means that you’ve been given an opportunity to flourish, but only if previous predators vanished or new habitats opened up. This gave rise to adaptive radiation. Adaptive radiation is when organisms become diverse rapidly into new forms. This typically happens when a change in environment makes new resources available, opens up niches and creates new challenge. This process results in speciation and phenotypic …show more content…
This shark has unique blood flow that circulates in opposite direction for an efficient transfer of metabolic heat.This allows for heat to exchange efficiently around the body in the brain, swimming muscles and stomach, so the Great White can go in waters too cold for other sharks. Reproduction for the Great White is like many other sharks, it generically uses internal fertilization to develop offspring. The mother carries the yolk like shelled eggs until body development is complete, this time period of her life is called ovoviviparity. After a year or longer he pups (baby sharks) are ready to be born in to the water. Right when the pups leave their parents they are forced to fend for themselves and live on their own. It can be said that it takes up to a whole year or longer for the mother to rebuild her energy before becoming a parent

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