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).
The Goblin shark (Mitsukurina owstoni) is a rare, poorly-known species of deep-sea shark. Sometimes called a  living fossil , it is the only living species in the family Mitsukurinidae.The Goblin shark can be easily identified by its long, flattened snout.Males can reach up to lengths of 12.6 feet (3.8 metres), and females can reach up to lengths of 12.2 feet (3.7 metres).he Goblin shark (Mitsukurina owstoni) is a rare, poorly-known species of deep-sea shark. Sometimes called a  living fossil , it is the only living species in the family Mitsukurinidae.