NameMarine Biology--Mr. Nelson
LAB: SPONGES AND COELENTERATES
Introduction:
Sponges and coelenterates are simple invertebrate animals. Sponges make up the
phylumPorifera, which means “pore-bearing”. The phylum is named for the many pores that cover the body of a sponge. Coelenterates are members of phylum Coelenterata (phylum Cnidaria is also used). Hydras, jellyfish, and sea corals are types of coelenterates.
Sponges have no true tissues or organs, no digestive tract, and no nervous system. Their bodies are loosely organized into two cell layers; the ectoderm and the endoderm. Support comes from hard structures called spicules or from flexible protein called spongin. Spicules are made of either calcium carbonate or silicon dioxide. Some sponges have both spicules and spongin.
Coelenterates have true tissues. Their bodies consist of two layers; an outer ectoderm and an inner endoderm. Between these layers is mesoglea, a jellylike material in which cells are embedded. Each coelenterate has a body cavity, or gastrovascular cavity, where food is digested. Coelenterates also have simple nervous systems that allow them to respond to stimuli.
In this investigation you will examine the characteristics of sponges and
coelenterates.
PHYLUM PORIFERA:
The sponges are among the simplest of the multicellular marine animals. Their well-known ability to absorb water is the result of numerous holes, pores, and chambers that perforate their bodies. Sponges are sessile and are usually attached to hard substrates such as rocks, pilings, or docks. Sponges are sometimes radially symmetrical but more commonly occur as asymmetrical growths or encrusting masses (symmetry will be discussed in class this week).
Sponges consist of several types of loosely aggregated cells that lack the organization and coordination found in higher multicellular animals. Water is circulated through the
central cavity, the spongocoel, to obtain suspended food and dissolved oxygen.
Procedure: All your sketches on this lab will have color and shading.
1. Sponge Structure: On the hard copy, DRAWINGS for Lab: Sponges and Coelenterates, there is a coloring sheet showing generalized sponge structure. Add the appropriate colors to this sponge structure coloring sheet.
2. Sponge Skeletons: Some sponge skeletons, such as those of the commercial bath sponge, consist of a flexible protein material known as spongin. Others have a mixture of spongin and spicules. The spicules of sponges are composed of calcium carbonate (CaCO3) or silicon dioxide (SiO2). Spicules are often difficult to see in a live sponge preparation, but they can easily be isolated for better observation.
3. Obtain a prepared slide of sponge spicules. On the hard copy, DRAWINGS for Lab: Sponges and Coelenterates, draw a few spicules under high power.
4. Using a regular (non-depression) slide and cover slip, obtain a sample of sponge spicules from Mr. Nelson. No air bubbles! Use the microscope (lower light is best, I think) and on the hard copy, DRAWINGS for Lab: Sponges and Coelenterates, draw a few of the spicules, under high power.
5. Wash and dry your preserved spicule slide. Leave it where you found itin your green tray.
Phylum Coelenterata (or Cnidaria):
The phylum Coelenterata includes a great diversity of uncomplicated yet versatile, marine animals. Corals, hydras, sea anemones, jellyfish, and all other coelenterates are characterized by radial body symmetry. Each possesses a centrally located mouth that leads to a dead end digestive sac, the gastrovascular cavity. The mouth and surrounding tentacles are capable of successfully capturing and ingesting a wide variety of marine animals for food. They capture their prey with stinging cells, called cnidocytes, cnidoblasts, or nematocysts, which are located all along each tentacle.
Coelenterates exist either as a free-swimming medusa (bell shaped) or as a sessile benthic polyp (vase shaped). The oral end of the polyp, bearing the mouth and tentacles, is directed upward. But in the medusa, the mouth and tentacles are oriented downward. Between the inner and outer layers of the body wall is a gelatinous mesoglea. The mesoglea of most medusae is thick and well developed, with a jellylike consistency that has earned them the descriptive, if misleading, common name of jellyfish. Many species of coelenterates alternate between a free swimming medusa generation and an attached polyp generation. In the life cycle of a generalized coelenterate, polyps can produce medusae or additional polyps by asexual budding. The medusae in turn produce eggs and sperm which, after fertilization, develop into a new polyp generation.
The phylum Coelenterata consists of three classes;
Hydrozoa(Hydra and siphonophores which include the Portuguese man-of-war, Physalia)
Scyphozoa (the true jellyfish)
Anthozoa (sea anemones, corals, and sea fans)
Each of these classes is characterized by its own variation of the basic coelenterate life cycle. Organisms in the class Hydrozoa usually have well-developed polyp and medusa generations. The polyp generation is often colonial, with various individuals of the colony specialized for a particular function. In the class Scyphozoa, the polyp stage is reduced or even completely absent. This class includes most of the larger and better knownmedusoid jellyfish. In the third class, the Anthozoa, it is the medusoid generation that is absent, and the sessile polyp form dominates. Many anthozoans, such as corals and sea fans, are colonial, but some anemones exist as large solitary individuals.
Class Anthozoa:
We will be looking at living representatives of this class. Anthozoan corals are much like the fresh water hydra we will looking at today. The difference is that coral secrete a skeleton house in which the polyps grow and they live in colonies. Corals are found in all seas, but the reef-building corals are limited to tropical and subtropical waters that remain warmer than 200C. Other types of corals are found at moderate depths throughout the world ocean. The calcareous skeletons of reef-building corals assume many growth forms depending on the pattern of polyp associations.
Procedure: All your sketches on this lab will have color and shading.
6. Get a depression slide and have Mr. Nelson place a living Hydra on your slide. You will not use a cover slip and you will be very gentle, as I will be using these Hydra with all my classes over the next few days.
7. On the hard copy, DRAWINGS for Lab: Sponges and Coelenterates,use medium power (low power if it doesn’t fit) to sketch your Hydra. Inside your sketch, include a measurement of the height of the hydra (in um).
8. As your watching through the microscope, gently take a toothpick and touch the Hydra. Be careful not to get the hydra stuck on the toothpick. BE GENTLE!
How does the Hydras body react?
9. Is this reaction an indication that Hydra have both nerve cells and muscle cells? Explain
10.Use high power to focus in on a tentacle. On the hard copy, DRAWINGS for Lab: Sponges and Coelenterates, sketch a tentacle to include the cells that you see.
11. Return your living, undamaged Hydra to Mr. Nelson. Get a prepared PhyasaIiatentacle from the lab cart. Use high power and, On the hard copy, DRAWINGS for Lab: Sponges and Coelenterates,sketch an area of the tentacle and include a cnidoblast (stinging cell). Label the cnidoblast (s) on your sketch.
12. Now you will take a depression slide and ask Mr. Nelson for a Hydra viridissima. On the hard copy, DRAWINGS for Lab: Sponges and Coelenterates, sketch this organism under low power.
13. Clean your slide and organize your area. When everything is ready, have Mr. Nelson check your group out. This way you avoid being the “official class cleaner-uppers”
Analysis: Use your textbook, notes, research and information in this packet to answer the questions.
1. Sponges were originally classified into the Kingdom Plantae. What characteristicsnecessitated that the Phylum Porifera be classified in the Animal Kingdom and not the Plant Kingdom.
2. What is the function of spicules?
3. What substances can the spicules be made of?
4. Sponges are an example of a “filter feeder”. What is a filter feeder and what role do the collar cells (choanocytes) play in this process.
5. Sponges can reproduce both sexually and asexually . Describe an example of each type of reproduction as it occurs in sponges.
* Sexual Reproduction Example:
* Asexual Reproduction Example:
6. On the hard copy, DRAWINGS for Lab: Sponges and Coelenterates, label the three body parts indicated on the Hydra diagram, as either Digestive Cavity, Tentacles, or Mouth/Anus.
DID YOU KNOW?: The Coelenterates only have 1 opening in their digestive tract located at the base of the tentacles. Therefore, food enters through the same opening as wastes are expelled (I call it the mouth/anus)....YUK!!!!
7. Use Figure 8-5 to answer the questions below.
8. Name two functions of a cnidocyte (a.k.a. cnidoblast or nematocyte) cell?
9. Unlike the solitary Hydra, the coral are colonial organisms. What does this term mean?
10. Which body type do the following Coelenterates exhibit as adults; Polyp or Medusa
a. Coral and Hydra?
b. Jellyfish?
11. Coral are organisms that produce an external house to live in. What is this skeleton house made of?
12. What functions does this skeleton adaptation provide to coral?
13. During our BFR Field Study, we saw that oceans naturally have an alkaline pH. As humans continue to pump CO2 into the atmosphere, on of the concerns is the affect of increased CO2 on the pH of oceans. Research this ocean acidification issue and find out what effects are being seen on coral reefs.
14. A symbiotic relationship is a close relationship between two different species in which one species lives on, inside, or close to the other species and at least one species benefits from the relationship. Review your drawing of Hydra viridissima. This species of hydra is a heterotroph but it has the ability to utilize an additional source of nourishment. Living symbiotically within the exterior tissues of this hydra are numerous unicellular, photosynthetic Protists (called zooxanthellae). What type of benefit(s) does this symbiosis provide to the Hydra?
--What benefit(s) does this symbiosis provide to the zooxanthellae?
15. There are three types of symbiotic relationships seen in nature:
*parasitism- one species benefits, the other is harmed by the relationship
*mutualism- both species benefit from the relationship
*commensalism- one species benefits, the other neither benefits nor is
harmed by the relationship
Based on your answer to the previous question, into which of the three types of symbiosis would you classify the relationship between H. viridissimaand zooxanthellae. Explain.