Blue shark

Blue sharks are sharks with a very dark blue color. Often, the blue shark travels alone. But they are called "wolves of the sea" because they sometimes form large packs, especially when there is food around. Blue sharks sometimes form schools (pack) with other blue sharks that are the same size. But the packs are always all-male or all-female. Nobody knows for sure why they do this.

The blue shark is a game fish, which means that people fish it for recreational purposes. So now, the blue shark is threatened because of overfishing.