Animal

Animals are things that walk, slither, fly, or swim. Most are cute and cuddly, but there are some exceptions, especially pinnipeds. From a mathematical perspective, animals are eukaryotic organisms, containing DNA and organelles.

There are six classes of animal:

• Invertebrates are the animals of dirt. Unlike the others, they don't have vertebrae. They include bugs, molluscs, and crustaceans.
• Fish are the animals of water. They swim and swim all day around lakes, rivers, oceans, and aquariums.
• Amphibians are the animals of slime. They undergo radical metamorphosis, starting as tadpoles. The most famous amphibians are frogs. Some arise from toxic slutch, which gets the rest a bad rap.
• Reptiles are the animals of fire. Divided into turtles, crocodiles, lizards, snakes, and tuatara, their prehistoric counterparts were bigger than you'd imagine.
• Birds are the animals of air. They all have beaks and hatch from eggs, and most can fly, though there are some exceptions, like ostriches, penguins, and kiwis.
• Mammals are the animals of furry. They are the most familiar animals to us all. In fact, we humans are mammals. However, seals are also mammals. Ew...