Asked by: Paul, via sciencefocus.com
Natural sponges are simple marine animals that don’t have any organs. Instead, they rely on their huge surface area to absorb oxygen and nutrients and to get rid of waste products. The flexible skeleton of these sponges (or the plastic equivalent in a synthetic sponge) holds water because the complex labyrinth of dead ends and narrow channels slows the water as it tries to drain away. Squeezing the sponge compresses the channels and the extra pressure helps to force the water out more quickly.