Unknown shark ID

Hi guys! It turns out we weren't catching black tip reef sharks, like we thought. Instead, we found out they were another small shark species, the spottail shark. They are in the same family as both black tip sharks and tiger sharks. What can you find out about the family, Carcharhinidae? What does it mean to be in the same "family" in science? Can you tell your teacher what Kingdom, Phylum, Class, and Order these sharks are part of? What kind of traits do animals in the family Carcharhinidae have in common?

Something else interesting about the unknown shark species--it turns out that our friends at Ocean Park, a small aquarium in Shark Bay, were catching black tip sharks in the Western Gulf, while we were catching spottail sharks in the Eastern Gulf. Why might the two gulfs of Shark Bay have different species of sharks living in them?