Echinodermata

Echinodermata - Characteristics and phylogeny of the spiny-skinned animals: sea urchins, starfish, and their allies.
http://tolweb.org/tree?group=Echinodermata&contgroup=Metazoa

Phylum Echinodermata - Some characteristics of the phylum that includes starfish, sea cucumbers, sea urchins, crinoids and brittle stars.
http://animaldiversity.ummz.umich.edu/echinodermata.html

Sea and Sky: Echinoderms - A brief description of the phylum followed by a long list of annotated photographs.
http://www.seasky.org/reeflife/sea2d.html

The Echinoid Directory - Project based at the Natural History Museum, London, aiming to provide information for amateurs and the scientific community on this major group of marine invertebrates with a long fossil record.
http://www.nhm.ac.uk/research-curation/projects/echinoid-directory/

Galaxy of Images: Starfish, Sea Lilies and Other Ecinoderms - Provides images from the printed books and manuscripts in the collections of the Smithsonian Institution Libraries.
http://www.sil.si.edu/imagegalaxy/imageGalaxy_collResult.cfm?term=Starfish%20%2D%20Sea%20Lilies%20%2D%20Other%20Echinoderms

Introduction to the Echinodermata - Overview of the systematics and ecology of starfish, brittle stars, sea cucumbers, sea urchins, and sand dollars.
http://www.ucmp.berkeley.edu/echinodermata/echinodermata.html

Gallery of Echinoderm Larvae - A collection of photographs of developing starfish and sea urchins with information about each.
http://www.microscopy-uk.org.uk/mag/artjul00/echino.html

Classification of the Extant Echinodermata - Describes the taxonomic groupings and provides links to images of some taxa.
http://www.calacademy.org/research/izg/echinoderm/classify.htm

Echinoderms - Descriptions of the major species of Echinodermata (starfish, brittle star, sea urchin, feather star, sea cucumber) with illustrations and links to photos.
http://www.starfish.ch/reef/echinoderms.html