Waterflea. Light micrograph of a waterflea, Daphnia pulex, a small freshwater crustacean. It maintains its position in the water by \rowing\" with the powerful, branched antennae (at upper right) to power it upwards, then slowly sinking whilst using the antennae like a parachute. This gives the waterfleas a jerky, hopping movement through the water. Waterfleas filter out microscopic algae with the organs at centre. This algae is then passed to the mouth for consumption. Waterfleas are often used in aquariums as live fish food. Magnification unknown."