Your Nearest Invertebrate Relative Is a Sea Squirt
Hippos are more closely related to whales than to any land animal. Elephants' nearest relatives are manatees, not rhinos. Your closest invertebrate cousin? The sea squirt — a blobby filter feeder stuck to rocks on the ocean floor.
The animal kingdom spans 800 million years of evolution, and appearances constantly deceive. Hyenas look like dogs but are closer to cats. Horseshoe crabs aren't crabs at all — they're closer to spiders. Lungfish are more closely related to you than to salmon.
Guess "tiger" when the answer is "house cat" and they meet at Felidae, the cat family — very close. Guess "tiger" when the answer is "hyena" and you'll be surprised how far apart they are.
256 species from jellyfish to mammals, all on a real phylogenetic tree. Convergent evolution means look-alikes can be strangers, and species that look nothing alike can be siblings.
Did you know?
- *Flamingos are more closely related to grebes than to any other bird, despite looking completely different.
- *Horseshoe crabs are more closely related to spiders than to true crabs.
- *Elephants' closest living relatives are hyraxes — small rodent-like mammals that fit in your hand.
- *Lungfish are more closely related to humans than they are to salmon.
- *Mushroom corals and jellyfish belong to the same phylum (Cnidaria), even though one is sessile and the other swims freely.
What is GuessKin?
GuessKin is a free daily guessing game built on real-world taxonomy. Choose from over 20 categories and try to identify the mystery animal. Each guess reveals how closely related your answer is to the target through a shared classification tree.
How does it work?
Every animal in GuessKin sits on a taxonomy tree — a branching hierarchy that shows how things are classified and related. When you make a guess, the game shows you the nearest common ancestor between your guess and the answer. The closer that ancestor is to the answer, the warmer you are. The tree visualization grows with each guess, narrowing down where the answer lives and helping you triangulate.
How to get the best score
- •Fewer guesses is better. The ideal game is guessing it in 1. Every guess counts against your score.
- •Speed matters too. The timer starts on your first guess. Quick, confident answers are rewarded.
- •Read the tree. Each guess gives you real taxonomic information. Pay attention to which branch the answer is on and which branches you've already ruled out.
- •Start broad, then narrow. Your first guess splits the tree. Pick something that gives you maximum information, then drill into the revealed branch.
Each GuessKin category uses a real classification system. These aren't made-up groupings — they're the same systems scientists and specialists actually use. New categories are added regularly. Every category is free, with no accounts and no ads.