With between 4 and 6 million species, insects are the most common animals on Earth. They populate almost every habitat from Antarctica to deserts, rain forests, lakes, mountain tops, glacier snow, and deep underground. A few live in the ocean.
Where there are insects, spiders feed on them. Ranging in size from just a few hundredths of an inch to giants with leg spans near thirteen inches, spiders are the ultimate insect hunters: stalking or building webs to catch them.
Animals with jointed legs are arthropods. Of these, only the insects have wings to fly, but air travel is an important method of dispersal used by other arthropods.