Sponges, Cnidarians

This laboratory exercise covers the following animals. You should learn this classification scheme and be able to classify the animals into these categories.

Phylums: Calcarea and Silicea (Sponges)

Phylum: Cnidaria

Class: Hydrozoa (Hydra and relatives)

Class: Anthozoa (Sea Anemones and Corals)

Class: Scyphozoa (Jellyfishes)

Sponges

Read “Sponges” in the lecture notes.

Preserved Specimens

1. Examine preserved sponges on display. Identify the osculum. Can you see pores?

Some of these specimens are shown below.

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Chalina	Spongila	Commercial Sponge

Structure of Sponges

The photographs below are of Grantia. The body of this species is highly folded producing many chambers. In the last two photographs, the living cells have been removed to reveal the spicules.

2. Examine the following prepared slides: Grantia c.s.and Grantia l.s. Find collar cells, epidermal cells, and pores. What is the function of the collar cells? What is the function of the pores?

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Grantia c.s. X 400	Grantia l.s. X 40

3. Examine a slide of Grantia spicules. What is the function of the spicules?

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Grantia spicules X 40	Grantia spicules X 100

Information to learn:

1. Be able to identify the phylum of any of the slides or preserved specimens. (Answer: They are all sponges.)

2. Be able to identify the osculum, pores, epidermal cells, choanocytes (collar cells), and spicules.

3. Be able to state the function of the osculum, pores, choanocytes, amoeboid cells, spicules, and spongin.

Cnidarians

Read the Cnidarians section of the lecture notes.

Hydrozoa

Hydra

1. Use a dropper to place a live Hydra on a slide. Examine the Hydra using a dissection microscope.

Hydra (Live) X 40
Hydra (Live) tentacle X 100

Click here: VIDEO - Hydra movement, X40, X100 (3.59 MB)

2. Hydra reproduce both sexually and asexually by budding. Try to find a live Hydra with buds. If you cannot find a live Hydra budding, look for budding in a prepared slide of Hydra.

Hydra budding This is a form of  asexual reproduction.	Hydra budding

3. Add a drop of vinegar to the slide containing Hydra. Describe what happened to the cnidocytes.

Hydra (Live) Exposed to 5% Vinegar Solution X 100	Hydra (Live) Exposed to 5% Vinegar Solution X 200

3. Examine microscope slides of hydra l.s. and hydra c.s. Look for the presence of two tissue layers. Identify a stinging cell (Cnidocyte).

Hydra l.s. X 100	Hydra c.s. X 100	Hydra c.s. X 200

 

Hydra l.s. X 40	Hydra l.s. with ingested food X 40

Obelia

1. Examine a preserved specimen of Obelia in a jar.

2. Examine a microscope slide of Obelia. Find feeding polyps and reproductive polyps.

3. Examine a microscope slide of an Obelia medusa. What reproductive cells are produced by Obelia medusae?

Obelia, preserved specimen	Obelia Colony X 40	Obelia medusa X 100
Obelia medusa in feeding position X 100

Other Hydrozoans

1. Examine preserved specimens of Gonionemius, Polyorchis, and Physalia.

Gonionemus, preserved	Polyorchis, preserved	Portuguese Man-Of-War

Sea Anemones and Coral (Class Anthozoa)

1. Examine a sea anemone and coral.

Sea anemone, preserved
Astrangia (Northern Coral) Skeleton	Coral Skeleton	Coral Skeleton

Jellyfish (Class Schyphozoa)

Examine preserved jellyfish on display.

Aurelia

Information to learn:

1. If you are shown any of the slides or preserved specimens, be able to classify them as being in the phylum Cnidaria. It may be helpful to use the photographs above when studying.
2. Be able to identify which are feeding polyps and which are reproductive polyps in Obelia.
3. Be able to recognize a slide of an Obelia medussa.
4. Tell how many tissue layers, the type of symmetry, and the type of gut found in cnidarians.
5. Be able to identify the mouth and tentacles in Hydra and sea anemones.