Week 4 Flashcards
list of phlya so far
protozoa metazoa parazoa eumetazoa radiata bilateria
two major groups within bilateria
protostomes
deuterostomes
two major groups of protostomes
lophotrochozoa
ecdysozoa
coelum
internal fluid filled body cavity
pseudocoelomates
have fluid filled cavity but mesoderm only lines outside, not gut
acoelomate
the only cavity is the gut tube, mesoderm region is solid tissue
pseudocoelomates
mesoderm inside the ectoderm, but digestive tract is not lined with mesoderm
coelomate
see the tube within a tube
cephalization
concentrate sense organs in one area (head) along with the control of the nervous system (brain)
better to know where one is going than where one has been
triploblastic bilateria
fate of blastopore
cleavage pattern of embryo
origin of coelomic cavity, if present
regulation of embryo development
fate of blastopore
a protostome (blastopore to mouth) b deuterostome (blastopore to anus)
cleavage pattern of embryo
a protostome- sprial
b deuterostome- radial
origin of coelomic activty, if present
a protostome- schizocoely
b deuterostome- enterocoely
regulation of embryo development
a protostome- mosaic (split embryo to death)
b deuterostome- regulative (split embryo to multiple embryo)
can protostome and deuterostome be grouped on evolutionary relationships and make monophyletic clades
yes
are diploblastic organisms acoelmate
no, they are not
are three major body plans make up clades
no
lophotrochozoa
groups with trochopore
ecdysozoa
groups with ecdyse or shed their integument
phylum platyhelminthes characteristics
“flatworms”- body flattened dorso-ventrally
acoelomate
protostome- one opening to digestive tract
bilaterians
mostly aquatic or parasitic
typically posses flame cells (protonephridia)
acoelomate protostome bilaterians
lack a coelom, mesoderm fills in space between ectoderm and endoderm, no fluid filled space
where does phlyum platyhelminthes live
marine and freshwater environments, some on land but require pretty moist environment
aquatic
water
marine
saltwater
what do platyhelminthes have on cnidarians
organ level of organization
cepahlization, some centralization of nervous system
digestive & excretory systems
what do platyhelminthes not have
respiratory system or circulatory system- still rely on diffusion
what makes diffusion possible in platyhelminthes
their flattened body
how does digestion work in turbellarians
they are predators, extracellular digestion via enzymes followed by intracellular digestion
have one opening gut, food waste is just spit out
where is mouth on a turbellarian
not on the head but on end of the pharynx that extends form mid- body
is the pharynx eversible
yes
eversible
can be extended
intestine in turbellarians
may be simple or branched in different species
do tapeworms have a digestive system
no, they absorb nutrients from host intestines through their tegument
parachyma
cellular, mesodermally derived true tissue
ectoderm
epidermis, sensory and nervous structures
mesoderm
musculature, gonads, parachyma
endoderm
gut wall
where is ectoderm seen
free living species
rhabdites
secrete mucus- mostly seen in free living groups
viscid and releasing glands (dual gland adhesive organs)
good for adhering to surfaces and then quickly detaching
anchor cells
two viscid glands and one releasing gland lie in parachyma, attached to a nerve
organism anchors to microvilli to substrate using excretions of viscid glands, then detatches by excretionsof releasing glands
where is ciliated cellular epidermis seen
free living groups
where is ectoderm - syncytial tegument seen
in parasitic forms
what is syncytial tegument
many nuclei occur within a single, continuous cell membrane,
non-ciliated protective layer, involve din host-parasite interactions, serves secretory and absorptive functions
neodermata
new skin, referring to this syncytial tegument
are rhabodites found in neodermata
no
flame cells
protonephridia
primarily for osmoregulation
protonephridia
first kidney
where can seletive reabsorption take place
along tube cell before exiting nephriodiopore
how does excretory system work
flagella beat and create negative pressure to draw water and waste products in through small perforations in weir
ganglion
simple anterior brain
rheoreceptors
detect water currents
statocysts
equilibrium
sense organs
ocelli
auricles
statocysts
rheoreceptors
how does the nervous system work in planaria
longitudinal nerve cords in pairs, carry nerve impulses to muscles, allowing coordinated activity
what does planaria represent with the central nervous system
simplest living animals with a CNS
platyhelminth reproduction
asexual
sexual
sexual reproduction in platyhelminth
most are hermaphroditic (monoecious)- some are dioecious
use cross- fertilzation
direct development in free-living & forms with single host
endoparasites have complicated life cycles & multiple hosts
asexual reproduction in platyhelminth
fission- binary, schizogeny
what do neoblasts allow
for planaria and other turbellarians to reproduce asexually via fission
neoblasts
adult stem cells, can also allow regeneration
pluripotent
cells that can generate any cell type
how much of planarian genes have human counterparts
about half
4 classes of Phylum Platyhelminths
Class Turbellaria
Class Trematoda
Class Monogenea
Class Cestoda
Class turbellaria
free living
Class Trematoda
endoparastic flukes
Class Monogenea
ectoparastic flukes
Class Cestoda
tapeworms (endoparastic)
non- Turbellaria
all parastic, can be grouped together in the Neodermata due to presence of tegument
Class Turbellaria characteristics
4,500 species
mostly free living
5mm-60cm long
most have ciliated epidermis
how does Class Turbellaria move
move by cilia, muscular undulations, or both
utilize mucus slime track and adhesive organs
life cycle of Class Turbellaria
simple, generally no direct development,
no distinct larval stages, juveniles hatch as miniature adults
is it more energetically taxing to maintain both sexes
Class Turbellaria
yes
what is the advantage of maintaining both sexes
Class Turbellaria
if there is not a lot of mates since mating will produce fertilization in both partners
penis fencing in flatworms
Class Turbellaria
one tries to stab the other to inseminate without getting inseminated itself
Class Trematoda Characteristics
20,000 species
flukes, all parastic
what are most Class Trematoda endoparasites of
vertebrates
what are some adaptations Class Trematoda have for parastitism
non-ciliated, synctial tegument- protective
feed by rasping host tissue, feeding on bile
penetration glands
suckers & hooks
glands to produce cyst material
increased reproductive capacity
where are organs involved in penetration of host tissues of Class Trematoda found
in cercaria
attatchment organs in Class Trematoda
two suckers are characteristic
why does Class Trematoda produce cysts
so larvae can encyst in tissues
major features seen in general in parasites
high reproductive output
put out a lot of eggs and embryos
why do parasites ouput a lot of eggs and embryos
not a great chance they will make it to next host so high output helps their chances
what is a sign of a good parasite
high reproductive output
not killing your host
Class Trematoda, Subclass Dignea complex lifecycle
at least 2 hosts
1-3 intermediate hosts (usually includes snails at some point) reproduce asexually
definitive vertebrate host- reproduce sexually
how many stages does Class Trematoda, Subclass Dignea have
can have as many as 7 life stages
how does the Class Trematoda, Subclass Dignea life cycle work
fertilization within vertebrate, eggs excreted( in urine or feces)
eggs hatch and form free living stage of life cycle
miracidium infects intermediate host- snail by active or passive transmission
undergoes asexual reproductin in intermediate host by sporocyst
sporocysts create redia
redia form cercaria
cercaria can infect definitive hosts by several routes- schistosmoa, can invade second intermediate host, form metacercaria, then be eaten by definitive host
miracidium
free living stage of life cycle
active transmission
free swimming miracidium disperse and penetrate intermediate host
passive transmission
eggs with miracidia eaten and hatch within intermediate host
cercaria
free swimming
schistosoma
burrows directly into skin
Class Monogenea characteristics
1,000 species
flukes, all parasitic- mostly ectoparasties on fish, have opisthaptor
simple life cycle
opisthaptor
attatchment organ, posterior
live cycle of Class Monogenea
egg> ciliated larva> attach to host
what do ectoparasites require?
well developed attachment organs
where does Class Monogenea live mostly
on gills or skin of fish
one species does infect mammals by parasitizing the eye of hippopotamus
what does Class Monogenea feed on
blood, mucus, and epithelial cells of host
does Class Monogenea cause a lot of damage
not usually, unless there are excessive parasite loads
Class Cestoda characteristics
tapeworms 3,500 species no digestive system scolex for attachment proglottids (strobilla) at least 2 hosts in life cycle
what kind of definitive host does Class Cestoda have
vertebrate
how does Class Cestoda absorb nutrients without a digestive system
absorb nutrients from host via diffusion, microtriches
what is the most common tapeworm species that infects humans
Taenia
how do you get tapeworms
by eating undercooked meat such as beef and fish
for Taenia who is the definitive and intermediate hosts
definitive host- humans
intermediate host- pigs or cows
life cycle of Taenia
eggs shed in human feces, ingested by pig or cow, larva migrate to muscles and encyst
cysts in undercooked meet or raw meat leads to infection in humans
how can cysticercosis occur in humans
if human ingests eggs and acts as intermediate, or if proglottid ruptures within human host eggs hatch, can lead to painful spot in muscles and also cysts in brain
