Sponges are the simplest animal.
Sponges are simple animals which live in water. Most sponges live in the sea, but a few live in freshwater. Like all animals, sponges are multicellular. That means they have more than one cell. Yet the cells in a sponge are not organized into tissues or organs, as they are in most animals. Sponges are made up of specialized cells within a jelly like substance called mesohyl.
Sponges are in the animal kingdom, not the plant kingdom! Sponges may look like plants, but they are really animals. Perhaps what makes sponges seem so much like plants is that they attach themselves to a rock, a coral reef, or the bottom of the sea, and stay there the rest of their life. They don't move from place to place like most animals do. Also, unlike most animals, sponges have neither bilateral or radial symmetry.
Did You Know?
Sponges are in the Phylum Porifera. The Phylum Porifera gets it's name from all the pores in sponges! If you say the word "Porifera" slowly you can hear the word "pore" in it!
The pores of a sponge allow water to flow into the sponge. - You can easily see the pores in this sponge.
Pores called Ostia
Sponges have many pores in them. The pores are called ostia.
A unique characteristic of sponges is that they have pores which go all the way through their bodies. Water flows into the pores and then comes out the top of the sponge!
Short Video About Sponges
A Project Guide to Sponges, Worms, and Mollusks
How Do Sponges Eat?
Sponges are filter feeds, like clams, baleen whales, flamingos, and some types of fish. Sponges take in food and water through their pores.
This Yellow Tube Sponge, like all sponges, takes in food through its pores.
How Sponges Eat
Sponges are saclike animals with many pores (holes).
On the inside of sponges are cells called collar cells or choanocytes. These collar cells have flagella on them.
As the flagella beat, water is pulled into the sponge through its pores. Tiny bits of food get stuck in the collar cells and are then digested by food vacuoles within the collar cells. The collar cells then release the digested nutrients into the mesohyl (the jelly like substance of a sponge). Special cells called amoebocytes (which get their name because they have irregular shapes like an amoeba) move throughtout the mesohyl carrying the nutrients to all parts of the sponge. The water then passes on into the hollow middle part of the sponge and out the top opening, which is called an osculum. The water carries the sponges wastes away as it flows out.
Watch water pass through the pores of a sponge and out the sponges top!
The video above on how sponges filter water is well worth watching! It's very short, yet shows quite clearly how sponges filter water through their pores!
Did you know sponge cells can identify other sponge cells?!
Unlike plants, sponges have what is called "cell recognition." This means that sponge cells can recognize other sponge cells. They know other sponge cells when they "see" them! In fact, in a study, a sponge was passed through a fine mesh. In the process, the cells became separated from one another. They couldn't fit through the mesh otherwise! Yet once on the other side of the fine mesh, they reunited again, to form a new sponge!
Sponges are Invertebrates, which means they don't have a backbone.
Sponges do have a form of skeleton though!
A sponges skeleton is composed of spicules and/or spongin. Spicules are like tiny needles made of either silica or calcium carbonate. Spongin is a flexible protein fiber. Some sponges have skeletons made only of spicules. Others have only spongin, and a few have both!
Sponges Are Many Different Colors, Sizes, and Shapes - Look at this variety of sponges!
Some Sponges Live In Fresh Water, Rather Than The Ocean
Here's a Barrel Sponge called Halichondria panicea
The sponge shown above is called a Stovepipe Sponge. Can you guess why?
Look at this old fashioned Lincoln Stove. Notice any similarity?
Giant Barrel Sponge
Here's another Giant Barrel Sponge
Giant Barrel Sponges are some of the biggest sponges in the Caribbean Ocean. They can grow up to 6 feet in height. Giant Barrel Sponges are sometimes called the "redwood of the reef" because of their size and longevity. It is believed that some Giant Barrel Sponges may be over 2000 years old.
Venus Flower Basket Sponge
Large Caribbean Barrel Sponges
- Caribbean barrel sponges - including some giant ones!
Check out these photos of Caribbean Barrel Sponges. In particular, take a look at how huge the the sponge is in the 3rd photo from the top!
How Sponges Reproduce
Sponges Reproduce By Budding (Asexually), Fragmentation (Asexually) Or By Sexual Reproduction.
Sponges have several ways of reproducing. Sponges can reproduce asexually by budding or fragmentation.
During budding, a small "bud" begins to grow on the parent sponge.
During fragmentation, a piece of sponge breaks off and grows into a full sized sponge.
Some freshwater sponges also reproduce by creating gemmules which are a little like seeds that rest quietly until environmental conditions are right for their growth.
Sponges also engage in a form of sexual reproduction. Most sponges produce both male and female reproductive cells. The sperm from one sponge enters the pores of another sponge and is taken by the collar cells to the eggs located within the mesohyl. Once the fertilized eggs have developed into larvae, they swim away, eventually attach to a rock, corral reef, or the bottom of the sea, and develop into new sponges.
How Sponges Reproduce
Sponges, Jellyfish, & Other Simple Animals
Important Things To Remember About Sponges
- They are animals. Not plants!
- They are filter feeders, taking in food and water through their pores.
- They can reproduce by budding, fragmentation, by creating gemmules, or by sexual reproduction, depending upon the type of sponge.
- Most live in salt water, but some live in fresh water.
- They are in the phylum Porifera.
- They have cell recognition, meaning sponges cells can recognize other sponge cells!
- They are invertebrates, but do have a form of skeleton.
- Unlike most animals, they attach themselves somewhere and stay there.
What brings you to this page on sponges today? - Are you a biology student or teacher?
More information about Sponges - For a variety of ages!
A List of Pages in This Biology Series
Homepage: Biology: Information, Videos, and Labs
Unit 1 on Cell Biology
Unit 2 on Genetics
Unit 3 on The History of Life on Earth
Unit 4 on Ecology
Unit 5 on Diversity
Unit 6 on All About Plants
Unit 7 on The Animal Kingdom: Invertebrates
Check back later for additional biology units!
© 2012 JanieceTobey
Comments? Questions? - I'd love to know you were here!
Alan Katz from Florida on January 10, 2013:
Great lens. My daughter and I really enjoyed it.
anonymous on December 29, 2012:
I had no idea they came in such odd shapes and sizes. Very interesting organism.
Wednesday-Elf from Savannah, Georgia on December 20, 2012:
What an interesting article. I never realized that sponges were 'animals'.
Network Guru on April 11, 2012:
awesome I will have my kid check this out lol
anonymous on March 11, 2012:
You had me saying "Porifera" very slowly and once again fascinated with your delightful teaching style, another beautiful presentation that certainly draws the interest for these wonderful members of the animal kingdom.
efriedman on March 06, 2012:
Good to see these excellent images of sponges along with useful information. I will link this lens to my Who Am I? Nature Study series of educational puzzles
Terrie_Schultz on March 04, 2012:
Ruthi on March 04, 2012:
I learned something today, thank you! I found it fascinating that sponges have the cell recognition ability!
Zut Moon on March 04, 2012:
I understood this ... well some of it anyway. I am a sponge myself ... an Information sponge on the Information Highway !!!
getmoreinfo on March 03, 2012:
Biology is fun
Anthony Godinho from Ontario, Canada on March 02, 2012:
Seeing these biology series lenses takes me back to my school days. Another very well done lens which I'm sure students will find useful...blessings! :)
TheBaseballCoach on March 01, 2012:
Very informative...learned a lot about the sea sponge today
anonymous on March 01, 2012:
Very nice and colorful resource of sponges!
MaggiePowell on February 29, 2012:
I'm a mom... need the info to answer all those questions!