The story of how the starfish got its arms reminds us that even animals that might be familiar to us today can have incredibly deep histories - ones that stretch back almost half a billion years.

Moving along with our study of the diversity of the echinoderms, we arrive at class Asteroidea, the sea stars or starfish, and class Ophiuroidea, the brittle stars. How many different kinds of starfish are there? What is their...

Continuing our study of the echinoderms, let's take a look at their body systems, especially the water vascular system and endoskeleton. What else can we say about their general anatomy and physiology? How do sea stars and sea urchins...

With the hemichordates covered let's check out the echinoderms. Echinodermata is the other phylum in the clade Ambulacraria, and they are found all around the world. The most familiar organisms in this clade are starfish or sea stars,...

This video provides a brief introduction to the characteristics and diversity of echinoderms, such as starfish, sea urchins, and sea cucumbers. This video is part of the 11-part series, Classifying Animals.

This video is a lesson on invertebrates, the largest group in the animal kingdom. It explains the two main groups of animals - vertebrates and invertebrates - and focuses on the characteristics and examples of invertebrates. The video...