The following tree gives a rough idea of the relationships between animal groups, particularly those which have venomous species. It is not a comprehensive list of groups, as that would be very large. Rather, the major and more well-known groups are shown. Venomous animals (only those which are regarded as dangerously venomous to humans) are shown in red. Following a link will take you to more information on that group.

Animalia
	Porifera (sponges)
	Cnidaria
		Anthozoa (sea anemones)
		Cubozoa (box jellyfish, Chiropsalmus, irukandji, jimble, morbakka)
		Hydrozoa (hydrozoans, bluebottle)
		Scyphozoa (hair jelly, blubber, moon jelly)
	Ctenophora (comb jellies)
	Bilateria
		Annelida (worms)
			Polychaeta (bristle worms, fireworms)
			Oligochaeta (earthworms)
			Hirudinea (leeches)
		Mollusca
			Polyplacophora (chitons)
			Bivalvia (mussels, clams)
			Gastropoda (snails, cone snails)
			Cephalopoda (cuttlefish, squids, octopi, blue-ringed octopus)
		Brachiopoda
		Bryozoa
		Nemertea
		Rotifera
		Platyhelminthes (flatworms)
		Chaetognatha
		Onychophora (velvet worms)
		Tardigrada (water bears)
		Nematoda (roundworms)
		Nematophora
		Arthropoda (joint-legged invertebrates)
			Insecta
				Dermaptera (earwigs)
				Siphonaptera (fleas)
				Hemiptera (bugs)
				Orthoptera (grasshoppers, crickets)
				Lepidoptera (butterflies, moths)
				Coleoptera (beetles)
				Diptera (flies, mosquitoes)
				Hymenoptera (ants, bees, wasps)
			Crustacea (crabs, lobsters, slaters)
			Diplopoda (millipedes)
			Chilopoda (centipedes)
			Xiphosura (horseshoe crabs)
			Pycnogonida (sea spiders)
			Arachnida
				Opiliones (harvestmen)
				Aranaea (spiders)
					Mygalomorphae (primitive spiders)
					Araneomorphae (advanced spiders)
				Scorpiones (scorpions)
				Acari (mites, ticks)
		Deuterostomia
			Echinodermata
				Crinoidea (feather stars)
				Ophiuroidea (brittle stars)
				Asteroidea (starfish)
				Holothuroidea (sea cucumbers)
				Echinoidea (sea urchins)
			Urochordata (sea squirts, cunjevoi)
			Vertebrata
				Chondrichthyes (sharks, rays)
				Osteichthyes (bony fish)
				Aves (birds)
				Amphibia (frogs, salamanders)
				Reptilia (reptiles)
					Squamata (lizards, snakes)
					Testudinata (turtles, tortoises)
					Crocodylia (crocodiles, alligators)
				Mammalia (mammals)
					Monotremata (platypus, echidnas)
					Marsupalia (kangaroos, possums, koala, quolls)
					Eutheria (placental mammals)