phylum platyhelminthes Flashcards
(18 cards)
What is the phylum that includes flatworms such as tapeworms, planarians, and flukes?
Phylum Platyhelminthes
Includes organisms that live in marine, freshwater, and damp land habitats.
What type of symmetry do flatworms exhibit?
Bilateral symmetry
This means they have a symmetrical arrangement of body parts on either side of a central axis.
What is the body structure classification of flatworms?
Triploblastic
This indicates that they have three germ layers: ectoderm, mesoderm, and endoderm.
What type of body cavity do flatworms have?
Acoelomate
This means they do not have a body cavity; organs are encased in solid mesoderm.
How do flatworms process information?
CNS processes info from nerve ladders
The central nervous system coordinates responses to stimuli.
What is the significance of flatworms being dorso-ventrally flattened?
Increases surface area for exchange and nutrient distribution
This adaptation allows all cells to be close to water or the digestive cavity.
How does gas exchange occur in flatworms?
By simple diffusion
All cells are close to water or the digestive cavity, facilitating this process.
What is the function of protonephridia in flatworms?
network of tubules that maintain osmotic balance by pulling fluid through branched ducts
What is unique about the digestive cavity of flatworms?
Only one opening
gastrovascular cavity serves both digestive and circulatory functions.
What type of feeding behavior do planarians exhibit?
They prey on smaller or dead animals
Planarians pour digestive juices onto their prey and then suck up the liquefied nutrients.
What are auricles in planarians used for?
Detecting chemicals in the water
This helps them locate food sources.
How do planarians move?
Via cilia that line the belly along a film of mucous
This allows for smooth movement across surfaces.
What are trematodes?
Parasitic flatworms like the human liver fluke
What are the reproductive characteristics of trematodes?
Alternating sexual/asexual stages
They require an immediate host for larvae development before infecting the final host.
What feature allows trematodes to attach to their host?
Oral sucker
This structure aids in their parasitic lifestyle.
What is a defining characteristic of tapeworms?
Lack a mouth and gastrovascular cavity
They absorb nutrients directly from the host’s intestines.
What is a scolex?
The head of a tapeworm armed with suckers and hooks
This structure is essential for attachment to the host.
What are proglottids in tapeworms?
Sacs of sex organs
They contain both male and female reproductive structures.
