There are well over 5000 known species of sponge. Most sponges are marine, although there are a few freshwater varieties. Filter and suspension feeding are common strategies in organisms that live attached to hard substrates like rocks, piers, or even other organisms. Some suspension feeders, like corals, do not actively pump water through their bodies. Other examples of filter feeders include clams and mussels. Sponges are a type of suspension feeder, but because they actively pump water through their bodies, they are more specifically called filter feeders. Organisms that eat organisms hanging in the water are called suspension feeders. Sponges eat phytoplankton and zooplankton suspended in the water. The flagella also help to create a current within the animal, assisting in the water flow. Digestion of food particles occurs within the cell. The collar cells have long, hair-like structures called flagella, used to catch food particles, which are taken into the cell for energy and nutrients. Others have multiple oscula through which water leaves the animal.Īs the water moves through the sponge, it goes through a feeding chamber that is lined with collar cells. Some sponges have one osculum at the sponge's top. Sponges pump water in through the pore cells, and release it through an opening called an osculum.

Some sponges are known to close their ostia in the presence of dangerous substances like toxins, preventing them from entering the animal. The phylum name, Porifera, is named for the characteristic pore cells, or ostia, which allow water to enter the organism.

Scientists believe that sponges were some of Earth's earliest animals, dating back to Precambrian times.Ĭells within sponges have different functions, but are not organized into tissues.

Life activities such as respiration and nutrition occur within individual cells-there are no organs or systems. The reason is that their body plan is simple, consisting of just two layers of cells. The Poriferans, or sponges, are considered to be the simplest multicellular animals. While many of us have seen common sea sponges, few people consider the interesting features of these animals. Marine Science: The Dynamic Ocean - Interactive Tree of Life Phylum Porifera

How do calcareous sponges move?