This title introduces readers to the huge whale shark and the tiny dwarf goby. Young readers will enjoy learning fun facts about these swimmers, including what they have in common and how they are different. Future marine biologists will be drawn to unique color photographs of these fish and their deep sea habitat. The book includes an activity or craft, a table of contents, a phonetic glossary, infographics, informative captions and sidebars, sources for further research, information about the author, and critical-thinking questions to help readers connect with the text.