Lab 07 Lower Inverts
Questions
EXAMINATION OF SPONGES
1. Examine the sponge specimens on display. Note the variety of sponge types and forms.
2. Examine the sponge model illustrating a single choanocyte chamber. Note the location of the choanocytes. Can you recognize other cell types?
3. Examine the commercially-prepared sponge skeleton (w.m.) slide. Compare it to the whole bath sponges provided. Draw a diagram of the spongin fibers observed under the microscope.
4. Examine the commercially-prepared Grantia spicules slide. Draw a diagram of these spicules.
CNIDARIAN ANATOMY AND DIVERSITY
1. Examine the model of Hydra illustrating its anatomy and morphology. Draw a simplified diagram that labels the following features: body column, mouth, tentacles, epidermis, gastrodermis, gastrovascular cavity, ovary, testis, and asexual bud.
2. Examine the slide labeled Hydra nematocysts. Identify some nematocysts and draw them.
3. Examine the Obelia hydroid colony w.m. slide preparation to identify both feeding and reproductive polyps. Then examine the Obelia medusa w.m. slide preparation. From your observations draw a detailed labeled diagram that illustrates the life cycle of Obelia.
4. Examine a preserved specimen of Gonionemus in a small dish of water under the dissecting microscope. Draw a labelled diagram of this animal that illustrates the following features: mouth, manubrium, tentacles, and gonads.
5. Examine the following slides illustrating different stages in the life cycle of the moon jelly Aurelia: planula, scyphistoma, strobila, and ephyra. Also examine a preserved specimen of an adult moon jelly, noting the following features: oral armrs, tentacles, rhopalia, gonads, and radial canals (drawing a labeled diagram would be useful). Draw a diagram that illustrates all of these stages as components in the life cycle of Aurelia.
6. Cut open one of the preserved sea anemones and identify the following features if present: mouth, pharynx, tentacles, gastrovascular cavity, mesenteries, and acontia. Also examine the commercially prepared Metridium (a small sea anemone species) slide. This slide illustrates both transverse and
longitudinal section through the anemone. It would be useful to sketch diagrams that illustrate the anatomy of a typical sea anemone. What are the functions of the mesenteries? Compare your observations to the sea anemone and Hydra models.
FLATWORM ANATOMY AND DIVERSITY
1. Examine the commercially-prepared slide illustrating stained whole mounts of planaria (Planaria Plain and Digestive Tract). Note the eye spots. Are these eyespots image-forming eyes? Also note the branched digestive tract. What type of gut do flatworms have?
2. Examine the commercially-prepared slide of the Chinese liver fluke, Clonorchis sinensis. Identify the following structures: oral sucker, ventral sucker, gut, excretory pore, testis, ovary, yolk gland, uterus, and seminal vesicle.
3. Examine the commercially-prepared slide of the human blood fluke, Schistosoma mansoni. Note the relationship between the male and female worms.
4. Examine the commercially-prepared slide illustrating different regions of the dog tapeworm, Diplylidium caninum. Indetify the following structures: scolex, mature proglottid, gravid proglottid, testis, ovary, uterus, vas deferens, vitelline gland, vagina, and genital pore.
5. Examine the slides that present different stages of fluke life cycles: sporocyst, rediae, and cercariae. Note how these stages fit into the life cycle of the Chinese liver fluke, Clonorchis sinensis.
STUDY QUESTIONS
1. Describe filter feeding in sponges. Be sure to mention the path of water through the sponge, the type food, and the role of the choanocytes.
2. List and describe the skeletal components of sponges. How would you distinguish between calcareous and siliceous spicules.
3. List and describe the functions of the various cell types of sponges.
4. Diagram a typical cnidarian life cycle such as that exhibited by Obelia. Be sure to indicate the following stages: polyp, medusa, sperm, egg, zygote, planula. Also point out where asexual reproduction, sexual reproduction, and growth occurs in this cycle.
5. Describe, with the aid of labeled diagrams, the structure and discharging of nematocysts. What kinds of stimuli are necessary for this discharge? What is the mechanism for discharge?
6. Describe polymorphism as it occurs in the Portuguese man-of-war. In your answer, list and define the function of each type of individual within the colony.
7. Compare and contrast flatworms to cnidarians in the following features: symmetry, gut plan, tissue layers, grade of organization, cephalization, nervous system, sense organs, excertion and water balance.
8. Describe the adaptations for a parasitic way of life exhibited by ecto- and endo parasitic flatworms. Be sure to give examples and compare them to free-living forms.
Vocabulary (Define)
ostium/ostia
osculum/oscula
choanocyte
pinacocyte
porocyte
archaeocyte
spicule
calcareous
siliceous
collagen
spongin
gemmule
medusa
polyp
oral/aboral
nematocyst
cnidocyst
cnidocyte
nerve net
diploblastic
radial symmetry
blind-sac gut
mesentery
gastrodermis
epidermis
mesoglea
ectoderm
endoderm
planula
bud
polymorphism
zooxanthellae
scyohistoma
strobilization
ephyra
velum
tetramerous
hexamerous
octamerous
pharynx
acoelomate
bilateral
cephalization
triploblastic
tegument
scolex
proglottid
rhabdite
endoparasite
ectoparasite