Epidemiologists study outbreaks of diseases, the causes, locations, and how various communities are affected, utilizing relative information to aid in the prevention of future outbreaks. Epidemiologists help to keep the public informed of methods to maintain and improve public health.
Based on these criteria, the smallest known extant shark species appears to be Etmopterus perryi, males of which mature at 16 to 17.5 cm TL and gravid females have been found at 19 to 20 cm TL (Springer & Burgess 1985).
Whale Shark. The Whale Shark is the largest and the heaviest living shark because its weight is more than 21 tons and its length is more than 12 meter. It is found in open oceans and warm waters. It feeds on plankton but some times it also uses other small fishes as food. It is not facing any serious threat of extinction as they are found in large numbers.