Name:

Phylum Porifera: Sponges

Domain: Kingdom:

Learning Objectives: *Refer to Kingdom Animalia Unit

Plan

Text page: 370 *This is required reading.

-Sponges belong to Phylum Porifera, which means “pore-

bearing” in Latin. This is an appropriate name as sponges are

very porous.

-Sponges are a very ancient animal. Because they are sessile,

Greek scientists believed they were plants!

Porifera Habitat

-Sponges are found in fresh and salt water.

-If sponges are sessile, how can they defend themselves from

predatory animals in their habitat?

1. Spicules. 2. Contain toxins. 3. Camouflage (colouration)

Porifera Classification

-There are close to 5,000 different species of sponges that are divided into three classes based on

differences in their skeletons.

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-You will explore this in more detail during the lab.

Porifera Structure

-What type of symmetry do sponges have? Assemetry

-Below is a diagram of a sponge (with a section cut

out). Label the following: Water flow, pore cell, incurrent pore, flagellae, choanocyte (collar cell), central

cavity, amoebocyte, skeletal fiber, osculum, epidermal cell, jelly-like layer.

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-Using the terms above, describe the movement of water through a sponge.

Flagella of the choanocytes beat constantly, drawing water through the pore cells, into the central cavity

and pushing it out of the osculum.

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Porifera Nutrition

- Sponges are filter feeders that sift tiny particles from the water that passes through them.

-Digestion in sponges is intracellular (it takes place inside cells). The stages in sponge digestion are:

1. Food is trapped by mucus on the collar cells (choanocytes).

2. Food is passed to the amoebocytes.

3. Amoebocytes digest food in a food vacuole and transport nutrients to other sponge cells.

Porifera Reproduction

-Sponges can reproduce both sexually and

asexually

-Through what asexual process do sponges

reproduce?

Budding or fragmentation.

Many buds lead to colonies of genetically

identical sponges.

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-In sexual reproduction haploid sperm is released to swim to another sponge, where it is collected by the

choanocytes and passed to the egg. A diploid zygote grows into a larva, which swims to the nearest

favourable location, settles and grows into a new sponge.

-Visit http://www.oceanicresearch.org/sponges.html to see images of a

spawning sponge.

-During harsh environmental conditions, freshwater sponges produce

structures called gemmules, which can survive freezing

temperatures/drought. These structures are sphere shaped collections of

amoebocytes surrounded by a tough layer of spicules.

Porifera: The Importance of Sponges

-What roles do sponges have in their habitats?

Filter debris from water

Habitat or food for other organisms

Commensalism (pulling food in water towards other organisms-sea cucumbers)

Boring sponges break down CaCO2 = clean up ocean floor.

-How are sponges useful to humans?

Chemical for medical drugs

Filtering water is ecologically important

Represent first animals for research

Porifera Summary

-Sponges have no tissues, though individual cells can sense and react to changes in their environment.

-Since the cell layers are loose federations of cells, they are not considered true tissues. As such, sponges

have a cellular level of organization

- Biologists hypothesize that the sponge lineage arose very early from the multicellular organisms that

gave rise to the Animal Kingdom. The choanocytes of sponges and the cells of living protists are similar,

supporting the molecular evidence that animals evolved from a flagellated protist ancestor.

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What’s wrong with Sponge Bob?

-Using you new found knowledge of sponges, name three things about Sponge Bob that are inaccurate

with the life of a sponge and one thing that is accurate. Explain your reasoning!

Accurate: Pores

Inaccurate: Bilateral symmetry, sensory organs, mouth, capable of

movement in adult form

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