LAS 9.pdf - BIO044: General Zoology (LAB) Module #9 Name: _...

BIO044: General Zoology (LAB)
Module #9
Name: __________________________________________
Section: _________ Schedule: ______________________
Class number: _________________
Date: _________________________
1
FLM 1.0
PLATYHELMINTHES (FLATWORMS)
Lesson Objectives:
At the end of the day, you will be able to:
1. Describe the characteristics of flatworms;
2. Identify the structures in the anatomy of a different
classes of flatworms and their functions
Materials:
Ballpens, erasers, pencils, colored
pencils, dissection kit, masks, disposable
gloves, petri dish, preserved specimens,
reference books, and module
References:
• Reece, J.B., et al. (2014). Campbell
Biology: Concepts and Connections,
9 th edition. Pearson Publication.
•
Hickman C.P., et al. (2008). Integrated
Principles of Zoology, 14 th Edition.
The McGraw-Hill Companies, Inc.
New York.
A. LESSON PREVIEW/REVIEW
Introduction (2 mins)
Phylum Platyhelminthes are known as the flatworms. Among them are both free-living (living
principally in fresh or salt water) and parasitic species (mostly endoparasites). Parasitic flatworms are known as
flukes and tapeworms , and they are widely distributed amount human beings and other vertebrates; they are
often pathogenic, and sometimes bring about the death of the host.
Activity 1: What I Know Chart, part 1 (3 mins)
(For this part, only answer the first column. Please leave the 3 rd column blank until you reach Activity 4 of this module.)
What I Know Questions: What I Learned (Activity 4)
1) What are the defining
characteristics of a flatworm?
2) What are the structural
adaptations found in
parasitic forms of flatworms?
Productivity Tip: Even though laboratory activities only focus on the morphology of the specimens, always
keep in mind who are the hosts of these parasites and the pathogens they carry.

BIO044: General Zoology (LAB)
Module #9
Name: __________________________________________
Section: _________ Schedule: ______________________
Class number: _________________
Date: _________________________
2
FLM 1.0
B. MAIN LESSON
Activity 2: Content Notes
Flatworms of Phylum Platyhelminthes exhibit many advances over the cnidarians. They are
triphoblastic , hence their structures are derived from ectoderm , endoderm , and mesoderm . The mesoderm
gives rise to all tissue between the epidermis and intestines (except the nervous tissue, which is from the
ectoderm).
They are best characterized by having a dorsoventrally flattened body . They are also bilaterally
symmetrical . Internally, they do not have a body cavity ( acoelomate ). The only space inside their body is the
lumen of their intestinal canal.
The Platyhelminthes is the simplest phylum of animals that has now developed an organ-system level
of complexity, but it still classified under tissue-organ level as most of its organ-systems are still in its
primitive state:
• Digestive system is incomplete , with only 1 orifice where food is taken in and waste is
released.
o An exception to this is the parasitic tapeworms of Class Cestoda, which do not have
digestive systems at all and only absorbs nutrients through their epidermis.