Basking sharks are the second largest fish in the seas, averaging about 25 feet long, though some have been reported at over 30 feet, and even 40 feet long.

Excerpts from NATURE examine interrelationships between sharks and other species in the marine ecology. Human impact in the ecosystem includes the shark fin industry.

This video-enhanced lesson focuses on symbiosis and ecological relationships. Using sharks and marine species as examples, students will investigate the many ways that species that live in close proximity to each other might interact in an ecosystem, and will then explore the ways that ecosystems can be thrown out of balance, often as a result of human action. (Grades 9-12)

Catsharks are generally small, usually less than 2 ½ feet long, and have cylindrical bodies, tapered at the ends, with two small dorsal fins set far back down the body.

View additional Web and print resources for NATURE's "Sharkland."

Longliners -- which set lines that can be up to 15 miles long and are laden with hundreds or thousands of baited hooks -- pose an increasingly potent threat to sharks.

View additional resources, online and in print, for NATURE's "Shark Mountain."

In this lesson students will learn about a complex and often-misunderstood animal, the white shark.

Learn the surprising truths behind the monster myths on NATURE's WHITE SHARK/RED TRIANGLE.

Great white sharks are tremendously difficult creatures to study. They don't respond well to captivity, and are next to impossible to observe closely in the wild.