Cetacea

例句：

1. 1. The fin whale is the largest member of the family.
   蓝鲸是这个家族中最大的成员。
2. 2. Cetacea are found in all oceans and seas around the world.
   鲸类在全世界的海洋和海域都有发现。
3. 3.Scientists study the behavior and habitats of different species of cetacea.
   科学家研究不同种类鲸鱼的行为和栖息地。