lec 11 Flashcards
turbellarians
Nervous system?
Tissues?
Epidermis?
flatworms
-have extensively cilliated, glandular epidermis
-multiciliated epithelial cells produces mucus
-acoelomate
-solidly packed w tissues
-ladder-like nervous
systems w anterior ganglion(brain)
-eyes at anterior end
-clusters of
chemoreceptors in extensions of head
how do the epithelial cells produce mucus in turbs?
via rod-shaped crystalline rhabdites
Turbellaria gut
gut may be simple and sac-like
or three-branched
or multibranched
excretion of metabolic wastes is via
turbs
protonephridia
how do turbellia digest
start digestion externally by secreting enzymes
on the food
how do turbellia egest
through the mouth
Turbellaria fertilizatoin
Sexes?
-typically hermaphroditic
- transfer is via copulation
-intromittent organ penis to vagina
- or traumatic insemination in
which sperm is introduced through the
epiderms
- penis-
fencing
Turbellaria reproduction
Turbellaria cleavage
only some turbellarians show classic spiral cleavage
Parasitic platyhelminths groups
Monogenea Trematoda (flukes) and Cestoda
(tapeworms
Parasitic platyhelminths differences from turbellarians
lack eyes, epidermis lacks cilia in adults, syncytial epithelium
syncytial epithelium
protect them from the host’s
digestive system
is a synapomorphy of the neodermata
Parasitic platyhelminths life cycle
produce lots of eggs
-final (= definitive) host is the site of sexual
reproduction
-one or more intermediate hosts
intermediate host in neodermata
-main function is
to enhance transmission to definitive host
-amplification of infective stages via asexual
reproduction
-altering behaviour of
intermediate hosts
Cohort Trematoda
Definitive features?
What gut?
Common name?
flukes
-oral sucker
-2-branched gut
trematoda nervous system
simplified
ladder-like nervous system
nervous system common
in parasites
reduced
Class/Cohort Cestoda
Hosts?
Gut?
Definitive features??
-tapeworms
-typically >2 hosts with final host being a vertebrate
-no mouth or gut
-adult has scolex
Trematoda definitive host and intermediate hosts
-definitive host typically a vertebrate
-intermediate hosts usually include a mollusc
how do trematoda feed
-taking it into the mouth
with the help of the pumping
pharynx
nutrients are taken
in by
Cestoda
pinocytosis
Cell drinking
Cestoda
segments
what do they contain
proglottids
-packed with
fertilized eggs
-eggs and sometimes proglottids leave host with feces
Nemertea
Circ system?
Common name?
Gut?
-ribbon worms
-share many traits with turbellarian flatworms
-complete gut with anus
-closed circulatory system that is eucoelomic
what is that wack ass tongue thing in nemertea
eversible
proboscis that is kept in a
rhynchocoel
rhynchocoel
is a eucoelomic
cavity
nemerteans method of catching prey
predatory and capture prey by
shooting out their proboscis via hydrostatic pressure
special proboscis
proboscis is tipped with one or more stylets that puncture the prey like a harpoon and may inject toxin
nemertea reproduction
external fertilizatoin
in some cases, sperm released outside female body in gelatinous mucus, then taken in by female and boom internal fertilization
nemertea development
Weirdness?
direct or indirect also pilidium larva
pilidium larva
in some taxa part of the larva pinches off internally and grows into the juvenile. juvenile then breaks out of larva and eats it, and takes up a benthic life
importance of parasitic platyhelminths
affect human and livestock health
Echinococcus canadensis(tapeworm)
cause hydatid cysts in many
organs in humans
invasive terrestrial flatworm
caused the decline and extinction of land snails
nemertean genus Carcinonemertes
live on the undersides of female crabs and prey on their eggs
-implicated in collapse of crab fisheries
Medical nemerteans
-produce defensive chemicals,
including a tetrodotoxin
-can be lethal if eaten
