Flashcards in Platyhelminthes and Bryozoans Deck (47)
What evolutionary adaptation do the Phyla Platyhelminthes and Bryozoa have?
Lophophore or Trocophore larva
Give the Taxonomy of Platyhelminthes.
Clade: Bilateria - Protosmia
Phylum: Platyhelminthes (flatworms)
What kind of Symmetry does Platyhelminthes exhibit?
First appearance of Bilateral symmetry
What is significant about the nervous system of Platyhelminthes?
Evolution of Cephalization
How many germ layers does Platyhelminthes have?
3 Germ Layers: Endoderm, Ectoderm, Mesoderm
Does Platyhelminthes have a Coelem?
No. Just a gut lumen (cavity)
What is the parenchyma?
Mesodermal cells that fill the space between gut and ectoderm
What advances did the Platyhelminthes make evolutionarily?
Nervous coordination and appearance of an excretory system
What kind of body plan do Platyhelminthes have?
Acoelomate Body Plan
-Gut lumen and two intestines (one on each side) running the length of the body
-Mesodermally derived Parenchyma fills up all other space between endoderm and epithilium
-The Pharynx (mouth) is in the center of the body
What Organ Systems does the Platyhelminthes have?
-Pharynx and intestine, no anus
-Nervous system connected to brain, Cerebral Ganglia
-Excretory System with flame cells
-Advanced reproductive system
Explain the excretory system of Platyhelminthes.
Uses Flame Cells
-Cilia within flame cells beat back and forth (Pressure gradient)
-Causes water to come in through openings
-Water absorbs solutes
-Excess water and waste exit body through protonephridia
Is excretion pooping? What is it?
Excretion is not pooping. It is osmoregulation and the elimination of nitrogenous wastes.
What are the two types of parasites?
Ectoparasites - outside the body
Endoparasites - in the gut lumen or in bloodstream
What are the life stages of parasites?
Adult: lives in final host, uses sexual reproduction
Larva: lives in intermediate host
-Can be active or encysted
-If active, larva may use asexual reproduction
How do parasites make up for complex life history and low probability of survival?
Gigantic reproductive effort (asexual or sexual)
How do parasites evolve over time?
Tend to evolve to become more "perfect."
-Having less of an effect on host
-Converges toward similar life-history and body plan as host
What are the types of symbioses?
Symbiosis - Living together
-Mutualism: both benefit
-Commensalism: one benefits and other unaffected
-Parasitism: one benefits and other harmed
How are Platyhelminthes modified for parasitism?
-modified epidermis that protects parasite from host and absorbs nutrition
Hooks and Suckers
What is the life history of the Class Trematoda (flukes) of Phylum Platyhelminthes?
-Adult Fluke lives in human liver
-Human poops out eggs which end up in water
-Snails eat poop and ingest eggs
-Eggs hatch and miracidium turns into redia in snail
-Redia leaves snail as Cercaria which is eaten by fish
-lives in fish muscle as cyst
-Fish is eaten by human
What is the life history of the Class Cestoda (tapeworms) of Phylum Platyhelminthes?
Tapeworms live in human intestine
-Humans poop on grass or open area
-larva in poop eaten by cow
-larva live in cow as cysts in the muscle
-undercooked cow meat eaten by humans
How can we prevent Platyhelminth parasites?
1. Use toilet with primary sewage treatment
-prevents eggs from reaching intermediate host
2. Cook food thoroughly
-kills the larval cyst living in the intermediate host
3. Drain pond and kill snails
-kills important intermediate host (disrupts ecology)
How many germ layers does Phyla Platyhelminthes have?
Triploblastic - ectoderm, endoderm, mesoderm
Is Platyhelminthes protostome or deuterostome?
What is the habitat that platyhelminthes lives in?
Marine, freshwater, and terrestrial
Does Platyhelminthes have a skeletal system?
How does Platyhelminthes feed?
Free living species feeds using gut
Parasitic species feed using tegument
How do Platyhelminthes move?
Gliding on cilia and mucus
What is the circulatory system of Platyhelminthes?
No circulatory system. Uses diffusion.
What is the mode of excretion for Platyhelminthes?
Protonephridia with flame cells