Imagine for a moment that you could cut off a finger and your hand could grow back a replacement finger. Even more miraculously, your cut off finger could grow into an exact copy of yourself. There would be two of you. This sounds like the work of science fiction, but this is real life for the animals of phylum Porifera, which are commonly known as sponges. You may have sponges in your kitchen, but the sponges that live in the ocean are different from these and have quite a fascinating story to them. Scientists believe that all animal life came from these simple sea creatures, and a lot can be gained from learning about their origins.
Sponges are the simplest and most primitive animals on Earth. There are 5,000 species of sponges that live in salt water and about 150 species that live in freshwater. Sponges are sessile animals, meaning that they are stationary throughout life. At a young age, sponges attach themselves on a hard surface like a rock or a coral and remain in that one place--stationary for the rest of their lives. Sponges range in size from as small as a pen cap to the size of a dinner table. All have an internal cavity and an asymmetrical body plan.
Watch the video below to get a good look at sponges, the different types, and all the places you might see them living.
So, what do you think of when you hear the word sponge? A tool used to wash dirty dishes? Those man-made sponges are made to look like and sometimes feel like the life forms called sponges.
There are actually somewhere between five and ten thousand species of sponge. They are classified into several classes including Hexactinellida, Calcares, and Desmongiae. The last of these include about 90% of the sponges in existence.
Sponges range in shape and size and live in both freshwater and saltwater habitats. Only about 150 species live in freshwater, though.
There are many different types of sponges and the species range in size, where they live, how they reproduce, and most importantly when grouping them--what their skeletons are made of.
Jot down an answer to each of these questions--or say the answer to yourself--before clicking the question to check your understanding of the characteristics and classes of sponges.
| Define Porifera. | Porifera is an animal phylum that is made up of the simplest animals on Earth: the sponges. |
| What type of habitats do sponges live in? | Sponges live in both fresh and salt water. |
| What characteristic of sponges is described as being planted to one spot throughout life? | Sponges are sessile animals, remaining stationary throughout life. |
