Lab 4 Flashcards
What are the primary characteristics of the platyhelminthes?
Bilaterally symmetrical, dorsoventrally flattened, lack a coelom, do not have organs or a circulatory system
Briefly describe class Turbellaria
Small flatworms, less than 1cm in length. Found in marine and freshwater (usually free living). Epidermis is ciliated and contains many secretory cells
Why must turbellarians live in water?
High surface area to volume ratio means they can dry out easily
Dugesia sp. belongs to a group of turbellarians often referred to as ______
planarians
Name the phylum, class, and genus of this organism. Name the structures indicated. Describe the branched intestine. How are wastes expelled?
Phylum - Platyhelminthes
Class - Turbellaria
Genus - Dugesia
A - Eyes
B - Pharynx, Protrusible, can spit it out to eat. It is at the posterior end.
The intestine of dugesia is highly branched so nutrients can be absorbed into coelom. wastes are expelled through pharynx or small wastes through thin body wall
how is the nervous system of Dugesia sp. arranged?
Longitudinal, compact near anterior (almost has distinct brain). Have distinct eyes, and cells for sensing pressure changes and chemicals.
How do Dugesia sp. move?
Via circular muscle contraction, squeezing and thrusting the body forward (similar to snake locomotion). Longitudinal muscles are used in a movement called “looping”, attaching the flatworm to a substrate with the anterior end, and inching forward the posterior end.
Why is Dugesia sp. considered more “advanced” than hydra?
Have a true mesoderm and are triploblastic.
The Cestoda are otherwise known as the _____
Tapeworms
Describe the characteristics of the Cestoda of the Platyhelminthes
Tapeworms are endoparasites, divided into a scolex, neck, and a series of segments called proglottids. Outer body layer called tegument is nonciliated, specialized for nutrient uptake
A _____ is a section of a tapeworm
Proglottid
What is seen on this slide? Name the phylum, class, genus and species to which this organism belongs. Name the structures indicated. What is the purpose of this structure?
The scolex (anterior end) of a Cestode (tapeworm).
Phylum - Platyhelminthes
Class - Cestoda
Genus - Taenia
Species - solium
A - hooks
B - Suckers
Purpose of scolex is to hook onto intestine
What is seen on this slide? Name the phylum, class, genus and species to which this organism belongs. Name the structures indicated.
A mature proglottid (body segment) of a Cestode (tapeworm).
Phylum - Platyhelminthes
Class - Cestoda
Genus - Taenia
Species - Solium
A - Ovary
B - Genital pore
C - Testes
Describe the basic features of Class Trematoda
Have suckers located ventrally in the region of the mouth, with a nonciliated tegument
What is the phylum, class, genus, and species of this organism? Describe structure A. Is there another structure similar to A? Name the other structures indicated. Does this organism have an anus?
Phylum - PLatyhelminthes
Class - Trematoda
Genus - Opisthorichis
Species - sinensis
A is the mouth, with a small oral sucker. There is a ventral sucker as well, and both are used to attach to surfaces in the bodies of those they are parasitizing.
B - Pharynx
C - Intestine
No anus.
What are the characteristics of the generalized mollusc?
- Head poorly developed (sometimes there is not a distinct anterior end) 2. Flat, muscular foot forms ventral body surface 3. Visceral mass is present 4. A shall covers the dorsal body surface 5. Mantle (dorsal epithelium) responsible for secreting the shell
To what phylum does this organism belong? Briefly describe this group.
Phylum Mollusca.
Molluscs live in marine, freshwater, terrestrial. Have a head, muscular foot, visceral massand calcareous shell secreted by the mantle. Mantle cavity usually contains gills. Digestive tract has a toother radula (in all groups but bivalves). Vascular system includes blood, hemocoel, heart.
What is the phylum, class, genus and species of this organism? Name the structures indicated. How is “C” adapted for its environment? Does this organism have eyes? What is the purpose of A?
Why are the shells of this organism divided into several pieces?
Phylum - Mollusca
Class - Polyplacophora
Genus - Katherina
Species - tunicata
A - Mantle (girdle), can create a vacuum to anchor Katherina to the flat substrate
B - Gills (in mantle cavity)
C - Foot, moves along bottom in water.
Eyes on shell, very small and primitive.
Divided to allow organism to withstand waves
