Flashcards in Lecture 3 DA Deck (128)
How many cell layers do worms have?
How are worms classified regarding their coelom?
What are blastocoelomates and acoelomates?
Blastocoelomates - gut isn't mesodermally derived, but has a body cavity. Only the outer wall is mesodermally derived.
Acoelomates - has a solid mesoderm, so no body cavity.
Which phyla of worms are coelomates, acoelomates and blastocoelomates?
Coelomates - Annelida
Blastocoelomates - Nematoda
Acoelomates - Platyhelminthes
Are Platyhelminthes free living or parasitic?
Has both parasitic and free living.
What kind of symmetry do Platyhelminthes have?
Are Platyhelminthes segmented?
What kind of gut do Platyhelminthes have?
Either a blind gut, or no gut.
What kind of shape do Platyhelminthes have?
What is the parenchyma?
Is the cellular filling between the epidermis and gastrodermis.
What kind of muscles do Platyhelminthes have (4)?
Longitudinal, circular, oblique and dorsoventral.
What kind of circulatory and respiratory system do Platyhelminthes have?
None, they rely on diffusion.
Are Platyhelminthes hermaphrodites?
What fills the blastocoele in Platyhelminthes?
What structure do Platyhelminthes have for locomotion?
Cilia on their ventral surface.
What is a protonephridia, and how does it work?
Tubule that runs from the parenchyma to pores on the outside of the body.
Is a blind ended tube, with a flame cell on the end, pore side.
Flame cell has cilia that beat to draw water down the tubule, where its filtered.
An excretory duct removes waste.
What are the classes of Platyhelminthes (4)?
What is the class tubellia considered?
What kind of worm are class turbellia classified as?
Which class are parasitic worms believed to be derived from?
What water environment do class tubellia live in?
Both fresh and salt water, land as well, if moist enough.
How much nerve development do class turbellia have?
They are cephalised with a complex nervous system.
What kind of sensory organs do turbellia have?
Light receptors and statocysts, as well as chemo and mechanoreceptors.
How do turbellia feed?
Has a muscular pharynx that extends out of the gut and can wrap around prey.
Can also be sticky.
What is the gut of turbellia like?
Can have numerous branches (up to 4), are classified on this basis.
How do turbellia move (3)?
Ciliary gliding - has ventral cilia, and secretes mucus onto substratum, glides across it.
Pedal waves - undulates one side of their body at a time.
Looping - loops head over heels, cartwheels across.
What is the most common mode of locomotion for turbellia?
How do turbellia have temporary attachment to substrata (3)?
Can have adhesive cilia, excrete adhesive or use pharynx as a sucker.
What is the duo-gland adhesive system?
Used by turbellia for temporary attachment.
Two types of glands ar eburied in the parenchyma, and extend to the epidermis.
One is the viscid gland which secretes sticky mucus.
The other is the releasing gland, which releases a chemical that liquefies it, typically acid.
What are rhabdites?
Capsules are secreted by glandular cells embedded in the parenchyma, and extend to the epidermis.
Absorb water, expand and secrete mucus.
How do turbellia reproduce?
Are monoecious, so to spread sperm, has a penis that is like a stylet, and will fence with another worm to inject sperm. Can have multiple penises.
When a turbellia egg is fertilised, what does it form?
What proportion of the phylum Platyhelminthes are parasitic?
What is the ancestral form of parasitic worms?
Free living worms
What have parasitic Platyhelminthes worms lost vs free living ones?
Lost complexity in the nervous system, is uncephalised and reduced.
Are parasitic worms cephalised?
What is a syncytial tegument?
Thick layer with microvilli on the surface.
Are the epidermis of parasitic Platyhelminthes ciliated?
How are epidermal cells attached to one another in parasitic Platyhelminthes?
They are multinucleated, embedded in the parenchyma, but cytoplasm extends out and fuses with each other.
What is the purpose of a multinucleated epidermal cells in parasitic Platyhelminthes (3)?
Thought to defend againt immune cells and digestion, and aid in nutrient transfer.
What are the three parasitic classes of Platyhelminthes, and are they ecto or endoparasites?
Monogenea - ectoparasite
Trematode - endoparasite
Cestoda - endoparasite
How do class monogenea feed?
Are very small, and suck out nutrients from outside the host.
How do monogenea spread?
Reproduce sexually, only produce 1 larva, which swims away to find another host.
How do monogenea hold onto their host?
Hooks on their mouth.
What are the primary hosts of class trematode?
What happens in a primary host vs an intermediary one?
They reach sexual maturity in a primary host, whereas an intermediary one is used to spread and reach the primary host.
In the liver fluke (trematode), how many hosts does it have?
3, humans - primary, with fish and snails as an intermediary.
What is digenea?
Having 2 or more hosts.
In the liver fluke, where are ferilised eggs released, what are they eaten by, and what do they develop into?
Released in humans, eaten by snails and develops into larva called miracidium.
What happens to miracidium in snails?
They produce sporocysts via asexual reproduction.
what do sporocysts contain, and what do they contain in them?
They have redia in them.
Redia have cercaria in them, which swim out and infect fish.
How do cercaria infect humans?
Humans eat infected, uncooked fish.
How can liver fluke be beneficial?
Reduces inflammation in coeliacs.
Of the parasitic Platyhelminthes classes, which is the most reduced?
What systems have the cestoda lost?
Nervous, digestive and sensory systems.
How do class cestoda attach?
Via a scolex on their mouth.
Aside from the scolex, what are cestoda made of?
Segment like strucutres called proglottids.
How do cestoda absorb?
Through syncytial teguments.
What can be found in proglottids?
Many ovaries and testis.
What is an oncosphere?
Shelled fertilised egg of cestoda.
What is the primary host of cestoda, and how does this host spread it?
Dogs are primary host, poops contaminated faeces everywhere.
What is a secondary host of cestoda?
A grazer will eat contaminated grass.
In a secondary host, where do cestoda migrate?
After infecting, they migrate to muscle mass and develop into hyatid cysts.
What do hyatid cysts have, and what is its purpose?
Inverted scolex, which pops out when eaten to attach to guts.
Aside from the gut, where can cestoda migrate to?
To the brain, where it becomes calcified, called hyatidosis.
Are phylum Nematoda free living or parasitic?
What kind of coelomates are Nematoda?
Do Nematoda have an incomplete gut?
No, its complete.
What is the body cavity of Nematoda like?
Small, filled with organs, called blastocoelom.
What is the blastocoelom thought to be a remnant of in Nematoda?
What are the key features of Nematoda (3)?
Round, but tapered on the ends.
Do Nematoda have a soft cuticle?
No, has a layered rigid one of collagen.
What is the purpose of the Nematoda's cuticle?
Reduces permeability to survive in harsh environments.
Do Nematoda molt?
Yes, they molt their cuticle..
How do Nematoda move? Do they use peristalsis?
They move by writhing, no peristalsis.
Do Nematoda have syncytial teguments?
Do Nematoda have locomotory or feeding cilia?
Are Nematoda cephalised?
Yes, complex brain with central ganglia.
Are Nematoda mono or diecious?
Do the free living Nematoda have larvae? What about parasitic?
Free living have no larvae, parasitic do.
Are Nematoda eutely?
Yes, they have constant cell numbers in adults.
What kind of habitat do free living Nematoda inhabit?
All habitats, fresh water, salt water, and land.
What are the parasitic classes of Nematoda parasites to?
Nearly all plant and animal groups, including invertebrates.
How does the hookworm (Nematoda) infect humans?
Burrows through feet.
How does the hookworm (Nematoda) spread?
Spreads by faeces.
Where do hookworms migrate to? How do they reach the intestines from there?
Lungs. Get coughed up, then swallowed to go to the intestine.
How do hookworms reproduce?
Aside from poo, how else can hookworms spread?
What is the coelom of phylum Annelida like?
Has a true coelom.
Are Annelida unsegmented?
No, theyre segmented.
How does the coelom affect the digestive system?
Cushions it, doesnt allow it to deform.
What is meant by metameric segmentation?
What is serial homology?
Body is divided into segments with serially repeating organs. Annelida are serially homologous.
What is an advantage of serial homology (3)?
Improves peristaltic movement.
Can have segmental polymorphism, each segment specialised for a specific function.
Can easily grow or regenerate by adding more segments.
How do Annelida move?
At one end, circular muscles contract, elongating it. Longitudinal muscles then contract, anchoring it. Happens along the body in a wave.
What are setae?
Hooks, used for traction. Found in Annelida.
What seperates the segments?
Peritoneum, via septa.
What kind of cuticle do Annelida have?
How do Annelida remove waste?
How many metanephridia do Annelida have, and how do they drain segments?
Each segment has one.
Each opens to the segment before it, via a ciliated funnel called nephrostome. Filtering happens here. Other end opens to the epidermis, called nephridiopore. Waste is expelled here.
Each drains the segment before it.
What are the classes of Annelida (3)?
Where do polychaeta live?
Mostly marine worms.
What is characteristic of polychaeta?
Has numerous setae, protruding out of fleshy lobes called parapodia.
What do polychaeta use setae for?
Locomotion, burrowing and traction.
Do worms have gills?
Polychaetes can have them.
What is a polychaeta larva called?
Do trochophores have cilia?
Yes, in bands.
Do trochophores have a gut and coelom?
They have a complete gut, but no coelom yet.
Can worms be sedentary?
Yes, class polychaeta of Annelida can burrow and extend tentacles or evert their pharynx.
How do some burrowing polychaeta feed?
Use fan like structures to pump water into the burrow, are specialised parapodia. Also secretes mucus to act as a net, which filters food. will periodically roll it up and eat it.
What are siboglonoid polychaeta?
Tube like worms, no gut, mouth or anus, and symbiotic with bacteria in an organ evolved from their gut that holds them. They are chemosynthetic, and it cultures them in return for nutrients.
Where do class oligochaeta live?
Mostly terrestrial, can be freshwater.
Do oligochaeta have parapodia or setae?
No parapodia, few setae.
Are oligochaeta hermaphroditic?
Do oligochaeta have larva?
How do oligochaeta reproduce?
Fill with sperm after copulating. The cliteelum creates a sheathe of mucus, which eggs are released into. Gets scrubbed off. Eggs form a cocoon.
What is the clitellum?
Patch like structure that secretes mucus.
Do class hirudinea have a clitellum?
Yes, but only visible during breeding season.
Are hirudinea segmented?
No, they have incomplete septa.
Do hirudinea have cedae?
What is seconary annulation?
Segments not visible outward, due to false rings, which doesnt correspond to actual segments.
How do hirudinea attach?
Do hirudinea have larva?
What is direct development?
No larval stage.
Where do hirudinea live?
Do hirudinea have suckers?
Yes, anterior and posterior.
How do hirudinea move?
Undulates its body.