Chemical Defense in the Marine Sponge

Lesson plan

Lesson Plan {Based on a 55min lecture/30 min lab class}

Phylum Porifera (Sponges)


Rationale Statement:

Students are expected to examine the members of the Phylum Porifera, describe their characteristics and demonstrate knowledge of their ecological roles.

Learning Objectives:

Students will be able to:

  • Appreciate the ecological roles of sponges.

  • List and describe the general features and characteristics seen in members of the Porifera phylum.

  • Relate sponge form to its functions.

  • Explain the process of filter feeding.


Materials:

  • 4-5 examples of sponges, including the common household sponge

  • Overhead projector, pens, and acetate sheets for the interactive note sharing

  • 1 sheet of plain white paper per student

  • Markers, crayons, or colored pencils


Introduction: (15 minutes) (see lesson notes [attached] ).

Four to five different examples of sponges will be presented to the class. Pass them around. Have students decide if sponges are animals or plants. Students must justify their position. Have students list those characteristics most similar to plants and those most similar to animals.

Characteristics similar to plants Characteristics similar to animals

  • Physical texture and appearance Do not have roots

  • Sessile Cannot perform photosynthesis

  • Lack muscles, nerves, organs Have reproduction

Discuss the phylum Porifera and explain that sponges are animals.

Interactive notes: (30 minutes) (see lesson notes [attached] ).

While sponge samples are circulating students will observe their characteristics the ecological uses of the sponge will be examined. The characteristics form and function will be addressed in a question and answer format style. Critical thinking and active learning will be utilized.

 

Laboratory exercise: (25 minutes)

 

Activity: (15 minutes) (will complete as homework).

The students will create a one page advertisement for selling a sponge. Included must be the attributes of a sponge, the ecological importance, and why the consumer wants to buy their sponge.


Assessment:

The teacher will circulate through the classroom monitoring the outcome of the students understanding of the lesson and topic. Query the students about the functions of the sponge, what each part of the sponge is, and what would happen if those parts were missing. Success will be based on the submission of the advertisement project.

 

LESSON NOTES (accompanies Lesson for Porifera-Sponges)

Phylum Porifera (Sponges)

 

General Characteristics

  • "pore bearers"

  • radial symmetry

  • among the most ancient of all animals

  • most are salt-water

  • inhabit sea (polar, tropic, low-tide and deep water)

  • adults are sessile

  • multicellular

  • heterotropic

  • three body plans (asconoid, syconoid, leuconoid)


 

     Form and function

  • body of sponge forms a wall around a hollow cavity

  • body has openings or pores which water moves through

  • water propelled by flagella (collar cells)

  • water delivers food and oxygen to the cells and removes wastes out the top opening (osculum).

  • gametes are transported through the water

  • spiney spicules interlock forming the skeleton

  • amebocytes produce spicules from calcium carbonate or silica

  • softer sponges are made up of a protein called sponging

  • are filter feeders

  • ameobocytes digest food

  • digestion is intracellular

  • chemical defenses

     

    Ecological importance

  • many marine animals are symbiotic with sponges

  • sponges are important to the diet of snails, starfish and protists

  • sponges help clean the ocean floor

  • used by humans hygienically

  • produce powerful antibiotics

  • other uses of chemical secretions