Crustaceans have jointed legs and a hard exoskeleton. They come
in many shapes and sizes. Crustaceans’ body shapes are so varied
that the only thing they all have in common is two pairs of
antennae at some stage of their life cycle.
You would probably recognize a crab, a lobster and a crawfish
(crawdad) but few people realize how many crustaceans live in the
world around us. More than 38,000 species of crustaceans are
known; most live in the ocean and many have not yet been named.
Several types of fresh water crustaceans live in vernal pools in
the Central Valley. You will discover a few here but there are
many more. Seek them out during the wet winter months when
the pools are full of water. They will be long gone by summer!
For 2 billion years, bacteria were the only creatures on Earth.
Long before the dinosaurs, a special type of bacteria slowly
increased the level of oxygen in the Earth’s air to 20 percent.
Without this oxygen other plants and animals could not have
evolved, including us.