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The Primitive Worms
These worms are distinguished from each other by their relative body plans. The flatworms (Phylum Platyhelimenthes) have flat ribbon-like bodies with no body cavity (coelom). The roundworms (Phylum Nematoda) have a primitive body cavity but no segments. The segmented worms (Phylum Annelida) have both a body cavity and segmented bodies.
In this unit, we will examine free living and parasitic worms, their environmental roles, and diseases they cause.
Did you think there could be so much diversity when it came to worms? The answer is yes. Read on ...
Instructions - complete the following
Planarians, Tapeworms, Blood Flukes, Liver Flukes and more exist in Phylum Platyhelimentes. In this group, major body systems come into focus, while there is not any true space made for their arrival. Organizing visual organs and nervous tissue in the head region also marks its arrival in a process known as cephalization.
Lesson
Lesson - Phylum Platyhelimenthes
Notes for Chp 27
As primitive worms evolved, a bodily space was needed to house the internal organs. This partially developed space, a pseudocoelom, arrives in Phylum Nematoda, also known as the Roundworms. If you've heard of the Golden Nematode, you've heard of this group.
Lesson
Watch the following
Video - Meet the Planarian
Video - the Pork Tapeworm
Video - Bloodfluke Lifecycle
Video - Trichinosis
Video - Hookworms
Video - Elephantiasis (Filaria)
Video - the Ascaris Roundworm Infection
Life Cycle Diagrams
Diagram of the Oral - Fecal Lifecycle
Another schisostome - the Swimmer's Itch Lifecycle
Advanced Worms - Phylum Annelida
The Phylum Annelida includes the segmented worms such as the common earthworm, some marine worms, and leeches (Class Hirudinea). These worms are known as the segmented worms because their bodies are segmented, or separated into repeating units. Most segmented worms feed on dead organic matter, while leeches can live in freshwater and suck blood from host organisms. Leeches can also be used medicinally to remove excess blood.
Segmented worms have a well-developed body cavity filled with fluid, which serves as a hydrostatic skeleton, a supportive structure that aids in muscle contraction. Segmented worms also tend to have organ systems that are more developed than the roundworms or flat- worms.
Instructions - complete the following
Lesson
Lesson - Phylum Annelida
Watch the following
How Earthworms Move - Animation
Lab Dissection Video - Dissecting the Earthworm
Lab Dissection Video 2 - Full Version, including external anatomy
Class Hirudinea Video - "Fetch me a Leech" - bloodletting & Physicians
Class Hirudinea Video - Medicinal Leeches & Limb Reattachment
Class Polychaeta Video - a Giant Pile Worm
Meet the World's Largest Earthworm --> video
Phylum Molluska
Perhaps the best example of a wide variety of attainable mollusks is along a walk on the beach. There you can find the calcified shells of many different types of mollusks, most typically clams, mussels, scallops, oysters, and snails. Another reminder of the treasures that mollusks yield up may be as close as a jewelry collection. There glossy pearls, mother of pearl, and abalone shells reveal some of the unique features of mollusks.
As you learn about the different types of mollusks and their characteristics, consider how these features help adapt the mollusks to their living conditions. Then also admire their features and see how people’s ingenuity has used the mollusk’s design and beauty for practical and decorative purposes.
Instructions - complete the following
Lesson
Watch the following
Cephalopod Amazing Camoflage & Defense
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