Platyhelminthes Flashcards
What is the definition of a platyhelminthes?
A acoelomate triploblast
What advent of the platyhelminthes is a common apomorphy across most living thngs
triploblasty
What is bilateral symmetry a harbinger of?
directive motion
What is undirected swimming
pholagic
Define protostomes
The original blastopore is the mouth
Spiral cleavage
Schizocoely
Define deuterostomes
The original blastopore is the anus
Radial cleavage
Enterocoley
Define Enterocoley
Al little bleb of cell comes off the endoderm, expands, and forms a middle layer called the mesoderm
Define Schizocoely
Little bits of mesoderm start near lip of blastopore, and expands filling the space between endoderm and ectoderm
Why is the mesoderm important? (3 reasons)
- Cavity to contain organs in
- Fluid in mesoderm acts as primitive circulation
- Ability to move digestive system independently of the body
come back to guys who lost the anus
aight
What is unusual about he pharynx of the planaria
extends from planaria on the ventral side
Define diverticulum
Branches of the digestive system that branch throughout entire body
What is unique about the reproduction systems of the planaria
Both female and male parts
What happens once the sperm and egg are united in the planaria
The zygote is released out of the planaria
What is the skeleton of the planaria filled with
squishy mesophil cells
Along with longitudinal muscle, what other muscle groups do planaria have
Dorsoventral muscle
Define a rhabdite
Little gnidocyte like cells that eject when the planaria is bitten into the mouth of the predator. Causes bad taste that causes the predator to spit it out.
Which side of the planaria is covered with giant cilia
The ventral side
Describe planarian nerve system
Two nerve cords that stretch from one end to another, one at either edge of the periphery. The have connectives like ribs connecting them. Congregate near eyespots to form cerebral ganglion.
What is the name of the regions sensitive to touch and the presence of certain chemicals.
auricles
What was the advantage of the pigmented eye cups?
the planaria can finally orient based on where light is coming from.
What is the name of the structure and system that pumps out excess water and waste in the planaria
Protonephrida
Describe how the flame cell and tube cell work.
The two cells are partially joined by a lattice work (which is permeable). The flame cell has cilia that propel the liquid and waste down the tube cell and out through the protonephridia.
What can most be attributed to the success of the platyhelminthes?
they were parasitic, invading the internal cavities of other animals
What is the big secret that allows the planarians to be such good parasites?
they can resist attacks of the immune system
How does the syncytial zone of the planarian help it resist immune attacks?
this zone surrounds the entire planarian, one continuous cell. If the immune system breaches one part, you have a continuous massive cell that can quickly bring reinforcements to fix the damage. It also has connexins to cell bodies in the body, so they can also send up reinforcements.
How do the microtrix help the planarian evade immune attacks
They snag recognition proteins from the host and affix them to themselves, so that the body thinks they are normal.
What is always the intermediate host of the planarian life cycle
the snail
what is the miracidium
The free living form of the fluke that seeks to find a snail host and turn into a sporocyst
What does the sporocyst in the life cycle of the fluke make?
Redia, which then turn into cercaria
What is the goal of the cercaria in the life cycle of the fluke?
To get inside a definitive host, such as a sheep.
