INVERTEBRATE LAB. Phylum Protozoa & Porifera

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1 INVERTEBRATE LAB Phylum Protozoa & Porifera... These are single celled animals that are usually microscopic but some are visible to the naked eye. Many marine protozoa build themselves shells or skeletons, and such has been their abundance over the millennia that these have accumulated to form layers of abyssal oozes and contributed to the formation of limestone and chalk. Members of two marine classes of the subphylum Sarcodina are: Radiolarians, which form skeletons or tests of silicon and/or strontium compounds and exhibit many beautiful shapes. They have exquisite siliceous skeletons that are rather like 3 dimensional snowflakes in their symmetrical form. Almost all have spiny processes. They are all planktonic and differ from foraminifera in that their protoplasmic processes are long, thin filaments that project from a central capsule which separates the inner mass of protoplasm (nucleus and oil droplets) from the outer vacuolated "flotation" layer. Radiolarians feed by collecting food on their protoplasmic processes. It is transported toward the center of the animal for digestion just outside the capsule. The radiolarians are among the oldest known protozoa, and their tests are abundant in marine sediment in many parts of the world. Foraminiferans which represent another group of Sarcodines. These are an ancient and important group of marine sarcodines which form tests of calcium carbonate or other materials. They live in these little shells that they secrete. They send out thin branching strands of protoplasm through tiny holes throughout the test. This web catches and digests diatoms and other small planktonic organisms. The shells can be chambered and different species make a great variety of spirals, cones, etc. The majority are either fixed or free bottom-living but some important ones like Globigerina, are planktonic. The shells of foraminiferans accumulate on the sea bottom and contribute to the formation of chalk and limestone. England's White Cliffs of Dover are made up largely of foraminiferan tests, as well as much of the Bedford limestone found in Indiana and Illinois, and some of the limestone that was used to build the Egyptian pyramids. The distribution of certain species of foraminifera is also important to petroleum geologists as an indication of ancient environmental conditions that may have been favorable for the formation of petroleum. Examine the slides/specimens and answer the questions for each station on a separate LABELLED paper. At the stations, Observe and draw: 1. 2 forminiferans 2. 2 radiolarians 3. Write a description of each in a form that you would describe it to a friend over the phone so they could draw it. Include as much minute detail possible.. 4. Draw and label a sponge. Include all parts including how it reproduces. Also observe the sponge spicule slides. 5. Draw 3 different sponge spicule shapes you observe Station 1 What is it? What are the indentations for? What can they represent? Station 2 What is it? What are these made of and what purpose do the spines serve? Station 3 What is it? What are these made of and what purpose do they serve. What organisms are these found in? Station 4 What kind of sponge is this? Calcarea Hexactinellida Demospongia What do people use it for? Station 5 What kind of sponge is this? Calcarea Hexactinellida Demospongia What material does this sponge use to build its structure? silica or calcium carbonate Page 1

2 Station 6. Sketch the slide with the cross section of the sponge. Label the parts. What's a Hexactinellid? spicules The hexactinellids, or glass sponges, are characterized by siliceous spicules consisting of six rays intersecting at right angles, much like a toy jack. Hexactinellids are widely viewed as an early branch within the Porifera because there are major differences between extant hexactinellids and other sponges. In particular, much of their tissues are syncitia, extensive regions of multinucleate cytoplasm. Some discrete cell types do exist, including archaeocytes. Furthermore, whereas other sponges possess the ability to contract, hexactinellids do not. Moreover, hexactinellids possess a unique system for rapidly conducting electrical impulses across their bodies, allowing them to react quickly to external stimuli. Demospongia The Demospongia is by far the most diverse sponge group. Greater than 90 percent of the 5,000 known living sponge species are demosponges. This ratio is not maintained in the fossil record, where less than half of the known genera and families are demosponges. However, the vast majority of living demosponges do not possess skeletons that would easily fossilize, thus their fossil diversity, which peaks in the Cretaceous, is probably an enormous underestimate of their true diversity. As their great number of species would suggest, demosponges are found in many different environments, from warm high-energy intertidal settings to quiet cold abyssal depths. Indeed, all of the known freshwater poriferans are demosponges Demosponge skeletons are composed of spongin fibers and/or siliceous spicules, though one genus (Oscarella) has neither. Demosponge spicules, if present, are siliceous, have one to four rays not at right angles, and have axial canals that are triangular in cross section. Demosponges take on a variety of growth forms from encrusting sheets living beneath stones to branching stalks upright in the water column. They tend to be large and only exhibit the leucon grade of organization Calcarea Memebers of the group Calcarea are the only sponges that possess spicules composed of calcium carbonate. These spicules do not have hollow axial canals. The Calcarea first appears at the base of the Lower Cambrian and has persisted until the present. Greater than 100 fossil genera are known. Like the Hexactinellida and the Demospongia, the calcarean sponges were at their most diverse during the Cretaceous. Today, their diversity is greatest in the tropics, as is the case with most marine groups. They are predominantly found in shallow waters, though at least one species is known from a depth of 4,000 meters. The fossil record of the Calcarea indicates that it has always been more abundant in near-shore shallow water settings. Calcarea Systematics The basal group of the Calcarea is the Heteractinida. The heteractinids are characterized by eight-rayed calcareous spicules, or derivative forms. They are known from the base of the Lower Cambrian. Heteractinids never achieved great diversity and were extinct by the end of the Paleozoic. The other two primary groups of calcarean sponges, the Calcinea and the Calcaronea, share a more recent common ancestor and are characterized by regular three- Page 2

3 rayed and four-rayed spicules. The Calcinea is difficult to characterize and thus may be paraphyletic. The Calcaronea is more likely a monophyletic group of sponges since they share characteristic larvae and choanocytes, presumably due to common ancestry. The Calcinea is known from the Permian, while probable calcaronean fossils have been identified from the Cambrian. Both groups persist with many representatives in today's oceans. HIGHER CLASSIFICATION OF SPONGES there are 4 classes of sponges: Calcarea found in shallow coastal waters all are marine Hexactinellida - glass sponges chiefly live in meter depth are syconoid sponges all are marine Demospongiae spicules are silicious if present otherwise skeleton is made of spongin or both variously shaped some are huge all are leuconoid all but two families are marine- Spongillidae and Metaniidae- are freshwater with about 300 freshwater species; in North America are about 27 species in 11 genera (most belong to Spongillidae) this is the group from which we get our commercial sponges Sclerospongiae have silicious spicules and spongin also have an outer covering composed of calcium carbonate Page 3

4 are leuconoid sponges Sponge Lab 2 Problem: Will a natural sponge or a synthetic sponge absorb more water? Objectives: -to determine if natural sponges or synthetic sponges are more absorbent. -to use statistical methods to compute data. Hypothesis: Complete on your paper What sponge type do you predict will hold more water? Explain why you think that. Materials: Sponge samples: natural and synthetic (man-made), Water, balances, graduated cylinders Procedure: Weigh the dry natural sponge sample to the nearest gram. Record in Table 1. Weigh the dry artificial sponge sample to the nearest gram. Record in Table 1. Place the natural sponge into a beaker of water until fully saturated. Take out, let excess water drip off. Extract the water into the graduated cylinder very carefully, making sure you catch every last drop. Measure the amount of water held by each sponge, make sure you measure from the bottom of the meniscus. Repeat 3 times to find the average amount of water your sponge could hold. Repeat for artificial sponge. Find the average absorbency: Total the 3 trials and divide by 3. Then find the average absorbency per gram, by dividing your Avg. Saturated (ml) by the Dry Weight (g). Record your information for the class Observation Table 1: Percentage of Sponge Absorbency. Dry Weight (g) Amount of water held when Saturated (ml): Trial Avg. Saturated amount (ml) Average ml/g Natural Sponge Artificial Sponge Table 2: Class Percentage of Sponge Absorbency. Page 4

5 INVERTEBRATE LAB Table 2: Class Percentage of Sponge Absorbency. Lab Group Natural Sponge Artificial Sponge Lab Group 1 Lab Group 2 Lab Group 3 Lab Group 4 Lab Group 5 Lab Group 6 Lab Group 7 Lab Group 8 Totals Avg. Absorbency Page 5 Conclusion Questions: 1. Explain if your hypothesis was correct or incorrect. 2. What sponge type is better at absorbing? 3. What do you feel contributed to this outcome? 4. What are some errors you may have made in this activity?