All species of sharks are carnivores, not omnivores. On rare occasions, a shark will dine on something other than meat, such as seaweed, but it happens so rarely that it's not common enough to change the shark's classification.
Sharks, especially tiger sharks, will often eat things that aren't even considered to be food. Trash in the ocean is the most common snack for these sharks. When a shark eats something such as a bottle or other waste material, it is usually done by accident.
An omnivore is an animal that eats almost anything. They consume meat and plant matter on a regular basis, and humans are good examples of omnivores. A carnivore dines on nothing but meat. Sharks, polar bears, tigers and foxes are all carnivores.