These blacktip sharks move their large tails from side to side to push themselves through the water.

More about sharks. Wikipedia article (http://en.wikipedia.org/wiki/Shark) National Geographic articles on sharks (http://animals.nationalgeographic.com/animals/sharks/) National Geographic article on whale sharks (largest fish in the sea) (http://animals.nationalgeographic.com/animals/fish/whale-shark/?source=A-to-Z) © 2013 Jerry Jindrich. All rights reserved. Revised 1/25/2016.