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9.2: Sponges

Difficulty Level: At Grade Created by: CK-12
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Do animals wash your dishes?

Natural sponges, like the one in the picture above, are actually animals taken from the sea! The sponges in your home, however, were most likely never living things. Most sponges used in kitchens today are made from unnatural materials.


Sponges (Figure below) are classified in the phylum Porifera, from the Latin words meaning "having pores." These pores allow the movement of water into the sponges’ sac-like bodies. Sponges must pump water through their bodies in order to eat. Because sponges are sessile, meaning they cannot move, they filter water to obtain their food. They are, therefore, known as filter feeders. Filter feeders must filter the water to separate out the organisms and nutrients they want to eat from those they do not.

The sponges often have tube-like bodies with many tiny pores.

You might think that sponges don't look like animals at all. They don't have a head or legs. Internally, they do not have brains, stomachs, or other organs. This is because sponges evolved much earlier than other animals. In fact, sponges do not even have true tissues. Instead, their bodies are made up of specialized cells that do specific jobs. For example, some cells control the flow of water, in and out of the sponge, by increasing or decreasing the size of the pores.


  • filter feeder: Animals that feed by filtering suspended matter and food particles from water.
  • sessile: Unable to move.
  • sponges: Ocean-dwelling, sessile invertebrates in the phylum Porifera.


  • Sponges are sessile filter feeders.
  • Sponges lack true tissues.


Use the resource below to answer the questions that follow.

  1. How do sponge cells work together?
  2. How do most sponges feed? Explain your answer as fully as possible.
  3. Where do sponges take in water? Where do they expel water?
  4. What evidence do scientists point to when they say sponges may be the oldest type of animal on the planet?
  5. What is the "heart" of sponges that controls circulation?


  1. How do sponges gain nutrition?
  2. In what phylum are the sponges classified?

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filter feeder Animals that feed by filtering suspended matter and food particles from water.
gemmule Internal buds found in sponges that are the result of asexual reproduction.
sessile Unable to move.
sponges Ocean-dwelling, sessile invertebrates in the phylum Porifera.

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Difficulty Level:
At Grade

Concept Nodes:

7 , 8
Date Created:
Nov 29, 2012
Last Modified:
Aug 30, 2016
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