VOA慢速英语:鲨鱼数量自1970年以来下降了71%

cartilage – n. a strong but flexible material found in some parts of the body (such as the nose, the outer ear, and some joints)

devastating – adj. causing great damage or harm

ecosystem – n. everything that exists in a particular environment

extinction – n. the state or situation that results when something (such as a plant or animal species) has died out completely

mammals – n. types of animals that feed milk to its young and that usually have hair or fur covering most of its skin

primary – adj. most important

replenish – v. to fill or build up (something) again

species – n. a group of animals or plants that are similar and can produce young animals or plants; a group of related animals or plants that is smaller than a genus