Ch 8: Platyhelminthes Flashcards
all bilateral animals are ? blastic
triplo
how did the need for cephalization and centralization arise?
- evolved when radial animals began moving along a surface to inc probability of finding food
- anterior end adapted to sense the oncoming env
bilateral guts
- usually a complete tube
- foregut and hindgut developfrom ectoderm
- midgut from endoderm
do all bilateral animals have an excretory system?
almost, yes, except the teeny tiny ones
are most bilateral animals proto or deuterostomes?
protostomes
5 characteristics of platyhelminthes
- bilateral
- dorso-ventrally flattened
- triploblastic but acoelomate
- digestive system is a gv cavity
- no separate circ system
2 features that help make platys good endoparasites
- small size, small eaters
- flat; can live in tight spaces
are turbellaria free-living or parasites?
free-living
trematoda/flukes are endoparasites with ? hosts
several
monogenea are ectoparasites with? hosts
1
cestoda/tapeworms are endoparasites with ? hosts
1-2
how do Turbellaria move?
use cilia, muscular creeping, swimming, slime for locomotion
what do the epidermal glands in Turbellaria prod and why?
abundant mucus for locomotion, and perhaps as predator repellant
a variety of other glands in Turb prod other substances like
adhesive substances
what is Turbs epidermus like?
ciliated, mono-layered
6 features of Turbs
- mostly free-living
- mostly bottom dwellers
- extendable pharynx usually near middle of ventral side
- relatively well-developed head and sense organs
- a true CNS and a “brain”
- 2 interconnected ventral nerve cords
what do Turbs eat?
bacteria, single celled algae, small animals, corals
how is prey captured? (5)
- by wrapping around it
- entangling in mucus
- pinning down with adhesive glands
- stabbing with penis
- secreting enzymes
how is food swallowed?
whole, or in pieces via muscular waves of pharynx
3 types of gut shapes
- many branches
- unbranched
- triclad (most common)
what are 3 ways a Turb can sense their env?
- tactile receptors
- chemo-receptors (turn towards food)
- ocelli (detect light and move away)
how do Turbs excrete?
via protonephiridia
protonephiridia
tubules that run the length of the body with periodic exit pores
what are flame bulbs made of
interstitial fluid drawn into tubes via ciliated side pockets in the protonephridia
how small can you cut a Turb where it can still regenerate?
1/300th of a body
asexual repro in Turbs
some spp pinch transversely
how do Turbs usually repro?
hermaphrodites with internal fert penis fence to determine who acquires the sperm and whose eggs get fertilized
marine species of Turbs have what kind of larvae?
planktonic Mullers larvae
how else can offspring be sprung in Turbs?
hatch into small versions of adults
2 characteristics of Monogenea
- ectoparasites of fish/amphibians
- have a single host
where do adult flukes live?
in definitive host, usually a vert
where do larvae flukes live?
intermediate host; invert - may have more than 1 int host
cellular epidermis is partially/completely shed during embryonic development and replaced with
syncytial tegument
syncytial tegument is (5)
- unciliated
- no intercellular spaces
- protects against host enzymes
- may help deal w/ changing osmotic env
- can act as absorbing surface
how many liver flukes actually find a host
very few
due to their lifestyle, flukes must be ? selected
r (prod a huge # of tiny offspring)
what diseases can liver flukes cause? (2)
anemia, liver disease
life cycle of liver fluke (6 stages)
- eggs in feces
- miracidium
(asexual repro) - sporocyst and redia
- cercaria
- metacercaria
- adults in liver
4 ailments blood flukes can cause
- weakness
- swollen spleen/liver
- small stature
- inc 2ndary illnesses
blood flukes and sex
- separate sexes
- odds of meeting are low, so when they meet the female lives in a groove in the male until they mate
life cycle of human blood fluke (6)
- mature flukes in blood vessels of intestine repro sexually
- fert eggs exit host in feces
- eggs develop in water into ciliated larvae
- larvae infect snails
- asexual repro in snail results in another type of motile larvae
- larvae penetrate skin and blood vessels of humans
4 ways to control blood flukes
- keep excretion away from w
- remove snail habitat
- remove snails
- medicine
6 features of cestoda
- specialized gut parasites
- adults lack many sense organs
- no mouth or gut
- absorb food directly via tegument
- attach to a hosts gut via scolex
- body is an assembly line of proglottids
how are proglottids formed
by strobilization at scolex end; fall off posterior end
each bag of gonads becomes
a bag of eggs
lifecycle of a tapeworm (5)
- onsosphere larva
- ingested by intermediate host
- metamorphs into juvenile metacestode
- eaten; adult in gut of definitive host
- eggs expelled with hosts feces
humans can be ? ? ? hosts
primary, int, and definitive
how are tapeworms fertilized?
internally via penis of adjacent worms, or themselves
