Invertebrates (animals without a backbone):
* Porifera (sponges): Simple, filter-feeding animals with porous bodies.
* Cnidaria (jellyfish, corals, sea anemones): Radially symmetric animals with stinging cells called nematocysts.
* Platyhelminthes (flatworms): Flat, unsegmented worms with bilateral symmetry.
* Nematoda (roundworms): Unsegmented, cylindrical worms with a tough cuticle.
* Annelida (segmented worms): Segmented worms with a body cavity and a closed circulatory system.
* Mollusca (snails, clams, squids): Soft-bodied animals with a mantle and often a shell.
* Arthropoda (insects, spiders, crustaceans): Segmented animals with jointed appendages and an exoskeleton.
* Echinodermata (starfish, sea urchins, sea cucumbers): Radially symmetric animals with a spiny skin and a water vascular system.
Vertebrates (animals with a backbone):
* Chordata (vertebrates and tunicates): Animals with a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail at some stage in their development.
* Fish (jawless fish, cartilaginous fish, bony fish): Aquatic vertebrates with gills and fins.
* Amphibians (frogs, toads, salamanders): Vertebrates that live in both water and on land, and have moist skin and webbed feet.
* Reptiles (lizards, snakes, turtles, crocodiles): Vertebrates with scales and lay eggs on land.
* Birds (feathered animals): Vertebrates with wings, feathers, and lay eggs.
* Mammals (animals that produce milk): Vertebrates with hair, mammary glands, and give birth to live young.
This list is not exhaustive, and there are many other smaller groups within these major categories. For example, within the arthropods, there are insects, crustaceans, arachnids, and myriapods. However, these main groups provide a good overview of the incredible diversity of the animal kingdom.
