Everyone has a favorite animal, but have you ever thought, what makes an animal an animal? Well the animal kingdom consists of many different kinds of groups, such as: mammals (like bears and cows), reptiles (like snakes and turtles), birds (like robins and eagles), amphibians (like frogs and salamanders), fish (like sharks and tuna), insects (like ants and bees), mollusks (like squid and mussels), crustaceans (like crabs and shrimp), arachnids (like scorpions and spiders), and more. You may have heard of a food chain, which is very essential to all living things (animals, plants, bacteria, fungi, and protists). It starts with plants, and next herbivores (plant-eaters) eat the plants, and then carnivores eat the herbivores, and more carnivores eat the other carnivores and so on (this can happen anywhere such as forests, the sea, etc.). There are many (maybe millions) of species of animalia (the scientific name of animal), from german shepherds to emperor scorpions and even to the grass cutter ant, but what makes an animal is, any living organism that actively acquires food, with a well defined shape and has a limited lifetime.