World Biodiversity Database - A growing taxonomic database and information system that aims at documenting all presently known species (about 1.7 million). Taxonomic trees, descriptions, synonyms, literature citations, and molecular database queries.
BioImages - Virtual Fieldguide for UK Biodiversity - Large selection of pictures of organisms, mostly British in origin. Images are an aid to identification, showing different stages, states and views of the organisms. Search the database or follow a taxonomic tree.
Biodiversity Explorer - Classification of all forms of life, with some photos. Has a strong South African emphasis.
Natural Perspective - Dedicated to the beauty and science of nature and to the joys nature brings to those who explore it. The material here is organized according to the biological principles of Taxonomy.
Natural Selection - A gateway to quality, evaluated Internet resources in the natural world co-ordinated by The Natural History Museum, London.
NCBI Taxonomy - Searchable and browsable taxonomy tree of organisms for which there are publicly available gene sequences.
Mikko's Phylogeny Archive - A compilation of various phylogenetic trees representing different views of taxonomy. Includes links to other taxonomic websites.
Flora and Fauna of the Great Lakes - Provides access to materials from the fish, mammal, and fungus collections of the University of Michigan, USA. Includes many images of specimens.
Survey of the Plant Kingdoms - Explores plant anatomy, taxonomy, and classification, from Monera through the higher plants. Includes descriptions as well as graphics and schematics.
BioLib - Taxonomic tree of plants and animals with a photo gallery and some checklists for the Czech Republic and Slovakia. In Czech and English.
Census of Marine Life - A global network of researchers engaged in a ten-year initiative to assess and explain the past, present, and future diversity, distribution, and abundance of marine life in the oceans.
World's Boreal Forests: Animal and Plant Species - Fact sheets and photos for mammals, birds, trees and other plants of boreal regions.
Canada's Aquatic Environments - Provides comprehensive information about the aquatic habitats, animals, and plants of this country.
HabitasOnline - Information on the plants, animals, and fossils of Ireland. Includes an encyclopedia of marine life of the UK. From the Ulster Museum Sciences Division.
Utah Conservation Data Center - Database of photos and fact sheets for animals and plants occurring in this state. Includes lists of sensitive, threatened, and endangered species.
Nature of New England - Photos, facts, and links to information about birds, butterflies, mammals, and wildflowers of this region.
Wikispecies - Wikimedia Foundation project that aims to catalog all species.
Tree of Life - Phylogenetic tree with information about the diversity of organisms on Earth, their history, and characteristics. An on-going multi-authored project hosted by the University of Arizona.
Discover Life - Information about taxonomy, natural history, distribution, abundance, and ecology of many species worldwide. Includes tools to identify, map, and database species.
Thomson: Free Resources - Includes the Index to Organism Names, a publicly available subset of TRITON the Taxonomy Resource, and the Zoological Record Thesaurus.
iSpecies - A species search engine from Rod Page of Glasgow University. Search on either the common or Latin name of a species. Results are generated by querying other data sources.
Canadian Biodiversity Information Facility: Integrated Taxonomic Information System - Searchable database of four kingdoms: plant, animal, fungi, monera. Search by scientific or common names, English or French.
Lepidoptera and Other Life Forms - Taxonomic tree of mammals, insects, birds, and plants. Includes common and scientific names, publication details, references, links, general range maps, and some images. Most complete for Lepidoptera.
Integrated Taxonomic Information System - Authoritative taxonomic information on plants, animals, fungi, and microbes of North America and the world.