Name
Marine Biology--Mr. Nelson
LAB: SPONGES AND COELENTERATES
Introduction:
Sponges and coelenterates are simple invertebrate animals. Sponges make up the
phylum Porifera, 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 wellknown 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 it in 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 known medusoid 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
PhyasaIia tentacle 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
characteristics necessitated 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. viridissima and
zooxanthellae. Explain.