Sponges

Sponges are an animal phylum consisting of around 5000-8000 known species (4,6)—and perhaps as many as 15,000 to 24,000 including those not yet described (2,6)—that live all around the world (5). They can be found in both marine and freshwater environments at any depth, though especially in coral reefs, mangrove habitats, and seagrass ecosystems (2). These creatures come in a huge array of colors and sizes (2,5,6)—measuring anywhere from 0.5 inches (1.3 cm) to 70 inches (178 cm) (6)—and can have bodies with shapes that resemble trees, cups, tubes, fans, balls, shapeless blobs, and more (2). Despite this great diversity in appearance, all sponges share a physical feature unique among animals: they have cells that can move freely and change forms, allowing the sponges to continuously reshape their bodies(1,2). Also, nearly all sponges have a body-plan that enables a simple lifestyle known as filter-feeding (2,6). (The exceptions are a group of sponges which are carnivorous, feeding on small crustaceans (5,7)). A filter-feeding sponge pumps water through pores in the outer layer of cells that surrounds its body and draws small food particles such as bacteria out of the water that comes in (1,2,4,5,6). The water keeps flowing in the same direction through a network of canals until it exits the sponge via one or more holes in the sponge’s body (1,2). Although early animal lineage patterns are still unresolved (2), the very simplistic animals of the sponge phylum may in fact have been the first multicellular animals to appear on Earth (2,6), probably descending from organisms similar to modern choanoflagellates 635-750 million years ago (2,3).

When you think about a sponge, you probably think of something used to wash the dishes in your home. But, believe it or not, sponges are also a group of water-dwelling animals with about 5000-8000 known species (4,6)—and perhaps as many as 15,000 to 24,000 including those not yet discovered (2,6) —that actually have a lot in common with the squishy, water-absorbing things sitting next to your kitchen sink! These strange creatures, which live around the world (5) in oceans and smaller bodies of waters at both shallow and deep levels (2), come in all colors and sizes (2,5,6,) from half an inch (1.3 cm) to five feet and ten inches (178 cm) (6). Their bodies can have shapes that resemble cups, tubes, fans, trees, balls, shapeless blobs, and more (2). But whatever their shape, all sponges share an amazing physical feature that no other animals have: the cells that make up sponges’ bodies can move around freely and change forms, allowing sponges to constantly reshape their bodies (1,2). Most sponges also have special bodies adapted to a lifestyle known as filter-feeding (2,6). (The exceptions are a bizarre group of sponges which are carnivorous, feeding on small crustaceans (5,7)). Filter-feeding sponges pump water into their bodies through special holes, draw small food particles such as bacteria out of the water that comes in, and then let the water keep flowing through a network of canals until it leaves the sponge through one or more other holes (1,2,4,5,6). If you think this sounds pretty simple, you’re right. Sponges are so simplistic they may be the most ancient animals on Earth (2,3,6)!

Sponges: Origins Video and Lesson Plans

More Resources About Sponges

About Shape of Life

Shape of Life is a series of FREE classroom videos based on an original PBS Series. Explore the beautiful evolution of the animal kingdom on planet earth. The series is NGSS aligned with exquisite focus on diversity, biodiversity, adaptability, body structure, design, behaviors, and the innovative scientists who explore these creatures.