Poriferan organisms are distinguished from other microscopic animals by the tubular structure of their cell walls. Poriferans have evolved a great range of specialized body shapes and adaptations, making them the most diverse group of animals on Earth. Poriferans include such familiar creatures as clams, mussels, and anemones.

While the majority of poriferans are filter feeders, some are direct Consumers (ie. they absorb organic material directly through their skin), while others are parasites. Poriferans also include a great many unusual and little-known species, which range in size from microscopic to towering ocean giants.