How life is classified and how the Taxonomy Explorer maps onto the tree of life
What is taxonomy?
Taxonomy is the science of naming, defining, and classifying organisms. Biologists use a hierarchy of ranks (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species) to group species by shared ancestry and traits. In this explorer, you filter by place and by “species class” — these classes are iconic groups (e.g. birds, mammals, insects) that correspond to kingdoms or lower ranks in that hierarchy.
Taxonomic ranks
From broadest to most specific, the main ranks are:
- Domain
- The broadest category (e.g. Bacteria, Archaea, Eukarya). Life is grouped into domains before kingdoms.
- Kingdom
- Major divisions within a domain. Animalia, Plantae, and Fungi are kingdoms you can filter by in this explorer.
- Phylum
- A major group within a kingdom (e.g. Chordata, Mollusca). Phyla group organisms by fundamental body plan.
- Class
- A group within a phylum (e.g. Mammalia, Aves). The “species class” filter uses iconic taxa that are often classes.
- Order
- A group within a class (e.g. Carnivora, Passeriformes). Orders group related families.
- Family
- A group within an order (e.g. Felidae, Rosaceae). Families contain one or more genera.
- Genus
- A group of closely related species. The first part of a species’ scientific name (e.g. Panthera in Panthera leo).
- Species
- The basic unit of classification. A species is a group of organisms that can interbreed and produce fertile offspring. Shown as cards in the explorer.
Kingdoms and iconic taxa in this app
The filters use “species class” values from iNaturalist. These map onto kingdoms (e.g. Animalia, Plantae, Fungi) and, for animals, onto classes or phyla (e.g. Aves, Mammalia, Insecta). The tree below shows how these groups relate.
Tree of life (groups in this explorer)
Simplified hierarchy of the kingdoms and iconic taxa you can filter by. Animalia is expanded to show the animal classes and phyla used in the app.
- AnimaliaAnimals — multicellular, eukaryotic organisms that ingest food.
- MammaliaMammals: fur, live birth, milk.
- AvesBirds: feathers, beaks, lay eggs.
- ReptiliaReptiles: scaly skin, typically lay eggs.
- AmphibiaAmphibians: moist skin, often aquatic larvae.
- ActinopterygiiRay-finned fish: bony skeleton, fins.
- InsectaInsects: six legs, often wings, exoskeleton.
- ArachnidaArachnids: eight legs, e.g. spiders, scorpions.
- MolluscaMolluscs: soft body, often a shell (snails, clams).
- PlantaePlants — photosynthetic eukaryotes (trees, grasses, mosses, algae).
- FungiFungi — absorb nutrients from surroundings (mushrooms, moulds, yeasts).
- ProtozoaProtozoans — single-celled eukaryotes, often motile.
- ChromistaChromists — diverse group including many algae and water moulds.
- UnknownObservations not yet assigned to a major group.