Insects and spiders have a system of small tubes through which oxygen passes to all cells of the body. An animal that captures other animals for its food is a predator. The animals that are eaten by other animals are the prey. Warning colors are bright, bold color patterns on animals that warn predators away. These animals usually can bite, sting, or simply taste bad.
Sponges live on the bottom of oceans, rivers, and streams.
The body of a sponge is like a bag with two layers of cells and an opening at the top. In between the layers are spiny or soft material from which the layers grow. The internal layers contain cells with flagella that cause water to flow through the body. Roundworms have smooth, rounded bodies with an opening at both ends- food is taken in one end and waste is discharged at the other end. Rich soil often contains millions of round worms that convert dead leaves and animals into humas.