how could Julio explain why all three species share some body structures and have some differences? why do only grizzly bears and sea otters have canine teeth?

Some species are similar in structure because they are evolved from the same ancestors while some differences are also present in them due to the changes occurs in the body because of adaptation to environmental conditions.

Grizzly bears and sea otters have canine teeth because canine teeth are used to crushing hard food materials such as fishes and shells.

Explanation:

Canine teeth are present in the grizzly bear and sea otters due to eating of food materials which are hard. Canine teeth used to crush the food materials.