Dolphins and porpoises

"Explores the similarities between dolphins and porpoises, and how to tell them apart. Discover how traits like body shape, nose size, and dorsal fin shape can be used to identify these underwater mammals. Additional features include a side-by-side comparison of the animals, an activity encouraging readers to demonstrate their knowledge, a phonetic glossary, sources for further reading, an introduction to the author, and an index"--Provided by publisher.