The invertebrates, or invertebrata, are animals that do not contain bony structures, such as the cranium and vertebrae. The simplest of all the invertebrates are the Parazoans, which include only the phylum Porifera: the sponges (Figure). Parazoans (“beside animals”) do not display tissue-level organization, although they do have specialized cells that perform specific functions. Sponge larvae are able to swim; however, adults are non-motile and spend their life attached to a substratum. Since water is vital to sponges for excretion, feeding, and gas exchange, their body structure facilitates the movement of water through the sponge. Structures such as canals, chambers, and cavities enable water to move through the sponge to nearly all body cells.

 Now complete the tasks on the list below:

• Begin by watching Parts of a Sponge 
• Watch Reproduction in Sponges 
• Go to this page, http://cnx.org/contents/GFy_h8cu@10.53:u3LCIpa2@8/Phylum-Porifera, and read the entire page
• The QR codes on the page that link to the following, be sure to take the time to visit each link below, or use the QR codes on the page.
• Filtering Barrel and Chimney Sponges 
• Sponge Animation: Wild Ride Through a Sponge 
• Interactive Sponge Identification Guide 
• The Wonderful World of Sea Sponges 
• Use the Glossary at the bottom of the page to help with the vocabulary for this week
• Use the Review Questions and Free Response questions to check for understanding

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