The 11 animal groups in this generator, explained
What is actually inside each pool, how many species each one holds, and why the numbers are not round.
The generator draws from 7,119 species, split into eleven groups. Those eleven are not a biology curriculum and they are not a taxonomy — they are a compromise between what people search for and what the source data can support. This page is the honest version of what each pool contains, so you can pick one that fits what you are doing instead of guessing from the label.
The counts
| Pool | Species | What it actually contains |
|---|---|---|
| Mammals | 800 | Everything from shrews to whales. The most familiar pool, and the one most likely to produce an animal your audience already knows. |
| Birds | 800 | Passerines dominate, as they do in reality. Expect a lot of small brown-ish songbirds and a few unmistakable ones. |
| Fish | 800 | Ray-finned fish mostly, plus sharks and rays. A useful pool when you want variety without leaving the familiar. |
| Reptiles | 798 | Snakes, lizards, turtles, crocodilians. Snakes are over-represented relative to what a class usually expects. |
| Amphibians | 795 | Frogs and toads mostly, then salamanders and newts, plus a small number of caecilians — legless, burrowing, and strange enough to derail a lesson in a good way. |
| Insects | 794 | Beetles, butterflies, moths, bees, wasps, ants, dragonflies. Names are often specific and useful; "beetle" rarely appears alone. |
| Mollusks | 751 | Snails, slugs, clams, oysters, squid, octopus. A wide range of body plans for one label. |
| Arachnids | 598 | Spiders, scorpions, ticks, mites. The pool most likely to produce a species nobody in the room has heard of. |
| Echinoderms | 459 | Starfish, sea urchins, sea cucumbers, brittle stars. Entirely marine, and the best pool for a drawing exercise about symmetry. |
| Cnidarians | 406 | Jellyfish, corals, sea anemones, hydroids. No faces, no fronts, no obvious way to draw them — which is the point. |
| Annelids | 118 | Earthworms, leeches, marine worms. The smallest pool, and the one where repeats across rounds are most noticeable. |
Total: 7,119. The counts add up exactly, which is the sort of thing worth checking before you quote a number at the front of a classroom.
Why the numbers are not round
The names come from the iNaturalist public API — a taxa search at species rank, pulled on 2026-10-13 — and then filtered to species that have a common name in the source. That filter is the reason the counts stop at 800 or 798 instead of continuing: species with a scientific name but no common name were dropped rather than given an invented one.
Two consequences follow. First, every name in the pool is a real species with a real source record, and every result links to that record. Second, the pools are not a complete list of any group — they are a sample of the species that people actually name in English. A mammalogist will notice that the 800 mammals are not a representative sample of 6,000-odd mammal species. They are a sample of the ones with common names, which skews towards larger, more familiar, more photographed animals.
Scientific names follow iNaturalist's taxonomy rather than any other authority. Where another source splits or merges a genus differently, this site follows iNaturalist. That is a choice, not a claim that iNaturalist is right.
Which pool to pick
A short decision list, based on what people actually use the tool for:
- Teaching a unit on vertebrates: use mammals, birds, reptiles, amphibians and fish as five separate rounds. The contrast between the five lists is the lesson.
- Teaching invertebrates: insects, arachnids, mollusks, echinoderms, cnidarians, annelids. Six rounds, and the class stops treating "invertebrate" as a single category.
- Younger students: mammals or birds. The names are recognisable and the pool does not produce parasites.
- Drawing exercises about form: echinoderms or cnidarians. No faces, no obvious front, which forces structural thinking.
- Trivia or quiz nights: arachnids. The names are hard without being unfair.
- Anything where you need a lot of rounds: avoid annelids. 118 species means visible repetition after a few rounds.
- Nothing fits: paste your own list. The custom pool accepts one animal per line and ignores the built-in data entirely.
What the pools leave out
Worth being explicit about, because the gaps are not obvious from the labels. There is no plant pool, no fungi pool, no bacteria, no dinosaurs. Extinct species are not included — every entry is a currently recognised species in the source. Domestic breeds are not included either: you will find Canis lupus familiaris as a species in principle, but not "labrador" or "tabby" as separate entries. If you need breed-level names, the custom list is the way to do it.
The other gap is geography. The pool is global, so a round can mix a species from Patagonia with one from Siberia with no indication that they would never meet. That is fine for a drawing prompt and wrong for an ecology lesson — in the second case, filter by region yourself or paste a local species list.
Related
- Using a random animal generator in the classroom — six lesson formats and which pool each one needs.
- Random animals for drawing and writing prompts — why the strange pools are the useful ones.
- Where the animal data comes from