If you draw a line down the middle of the body, both sides are mirror images of each other. With a head and stereo senses leading the way, this body plan is ideal for active hunters. [2:49]

The Monterey Bay Aquarium Research Institute launches an expedition to explore the depths of the ocean in search of cnidarians. Scientists find that jellyfish and other cnidarians are dominant in both moderate depths and the deep parts...

Mitch Sogin analyses the genes of a sponge in his search for the origin of animals. In order to sequence the genes, he extracts them from the cells. We see the threads of DNA in a test tube. He compares a similar gene found in all the...

The human body plan is bilateral with symmetrical sense organs, a fast responding brain, half the body weight in muscles, a powerful heart, and miles of arteries and veins and a brain that coordinates it all. All large active animals...

The scientific fields of paleontology, embryology, anatomy, and genetics have all contributed to a new view of the evolution of the animal kingdom. [3:42]

Jenny Clack visits a site with fossilized tracks of an early tetrapod. She and her assistant hypothesize about what the animal was doing around 370 million years ago. [8:22]

We think that humans are at the top of the evolutionary ladder. But is being big, brainy, and fast the best design? Evolution has produced many animals with different approaches to life. Every animal is uniquely adapted to win at the...

The flatworm's bilateral body plan has a head with a brain and stereo eyes that enable it to actively hunt. Its mouth and pharynx are in the center of its underside. With no circulatory system, the gut distributes food to all parts of...

A video describing an amphioxus, a worm-like animal, that is our ancestor with numerous common features including the precursor to the vertebrate backbone. Learn how some chordates like tunicates, salps, and larvaceans, have remained...

Learn through this video about marine arthropod such as crabs, shrimps, and lobsters. Understand that these animals have jointed appendages that are both strong and flexible which they use for sensing the world, feeding, and moving....

An animation showing that molluscs' basic body plan includes a foot for mobility; a mantle that secretes a shell and a radula for eating. Learn that molluscs today show many variations on this original body plan. An abalone escapes a sea...

In the Inyo Mountains of California, paleontologist James Hagedorn looks for clues in the rocks for organisms that lived over 500 million years ago,a hard thing to do since most organisms weren't preserved. Watch him in this video as he...

Amphioxus' body plan shows what a vertebrate's ancestor might have looked like with a nerve cord, a brain, gill slits, segmented muscles and a notochord that would become the discs in the backbone. [1:31]

Kristi Curry-Rogers wants to understand how dinosaurs got to their gigantic sizes. Follow her on her journey as a paleontologist as she looks for fossilized dinosaur bones and then analyzes the bone tissue to see how fast the animal...