ANIMALIA
PLATYHELMINTHES LAB
References: Chapter 26.3 in Glencoe “Biology” and Chapter 27.3 in Addison-Wesley “Biology”
Purpose:
To observe the differences between the three (3) classes of phylum platyhelminthes.
Procedure:
1. Sketch Planaria, digestive system stained, under low power. Label the pharynx,
mouth, digestive cavity, and eye spots.
2. Sketch the anterior end of Fasciola hepatica (liver fluke). Label the oral sucker,
ventral sucker, uterus, testes, yolk gland, and intestines.
3. Sketch each of the four (4) sections of Taena pisiformis (beef tapeworm). Label
the scolex, hooks, suckers, immature proglottids, mature proglottid(ovaries,
testes, genital pore, yolk gland)and ripe section.
Observations:
The six (6) diagrams listed in the procedure. Include all parts mentioned above and the
apparent magnification.
Discussion:
Answer the following questions in full sentences.
1. a)Describe flatworm symmetry. Compare the flatworm symmetry to that of the sponges
and cnidarians. (3 marks)
b) What are the advantages of the flatworm’s symmetry? (2 marks)
2 a) Describe ingestion and digestion in the Planaria. (4 marks)
b) Why do you think the digestive system is so highly branched? (1 mark)
3. The flame cells belong to which system? Describe this system. (2 marks)
4. Planaria are hermaphrodites. What does this mean? Describe two advantages? (3 marks)
5. What role do Planaria play in a healthy ecosystem? (1 marks)
6. Describe precautions humans can take to disrupt the life cycle of the beef tapeworm. (2 m)
7. Describe precautions humans can take to disrupt the life cycle of the liver fluke. (2 marks)
** See back for Conclusion**
Conclusion:
Answer the following questions together in paragraph form. Be sure to begin your
conclusion with a restatement of the purpose in your own words.
i)
ii)
Why do most parasites not kill their hosts?
Even though Planaria and tapeworms are in the same phylum, they are very
different. Give four (4) functional or structural differences between the two
organisms, and give reasons for these differences.