Embryonic Development and Symmetry Flashcards
a zygote is a
multicellular organism
A zygote cell is a diploid cell resulting from the union of two what?
two haploid gametes
an embryo is a young animal or plant while..
it is still contained within a protective structure
the embryoe is NOT exposed to…
the environment
what are the two major processes occurring during embryonic development
cleavage and gastrulation
what is cleavage
first cell divisions in the embryo
what is gastrulation
in-folding, invagination
- the process forms embryonic tissue layers (2-3) from the first layer of cells
Gastrula
layers of embryonic cells are formed = germ layers
the ectoderm is the
outer skin
- epidermis
- nervous system
the endoderm is the
inner skin
- lining of digestive AND respiratory system
organisms with 2 germ layers are
diploblastic (with two buds)
Mesoderm is the
middle skin
- most internal organs: muscles, skeletal system, heart, stomach
Organisms with 3 germ layers are
triploblastic - three buds
Archenteron =
old gut
- digestive spaces (gut cavity)
blastopore is the
mouth or anus
what do tissues enable?
complex body organization
what does the gut enable?
extracellular digestion - large food items possible
cnidaria are
diplobasltic, blind gut, radial symmetry, multicellular
flatwroms are
triploblastic, blind gut, bilaterally symetrical
3 types of symmetry
asymmetrical
radially symmetrical
bilaterally symmetrical
asymmetrical
no axis divides body into equal halves
radially symmetrical
along one axis - as long as one cuts through centre- body can be divided into equal halves from many angles
bilaterally symmetrical
-single axis divides body in equal hlaves
examples of cnidarians
-jellyfish, sea anemones, corals, hydrozoans
how many species of cnidarians are there
11,000
cnidarians are…
diploblastic
cnidarians have what kind of tissues?
nervous and muscular
most life cycles include both of these body forms
polyp - sessile
medusa - motile
how do cnidarians obtain energy
- carnivorous
- using cnidocytes to caputre prey, inject prey with venom and stick to prey
another way cnidarians obtain energy?
extracellular digestion in gastrovascular cavity
- corals can obtain a large proportion of their energy from symbiotic algae
How do cnidarians reproduce?
budding
do cnidarians have simple nervous systems or complicated ones?
simple.
which direction can sensory information come from (cnidarians)
ANY!
Hydra
simple nerve net
what do cnidarians have instead of brains?
Hydra connecting everything together
Hydrozoa
- polyp dominate phase
- most species alternate between polyp and medusa
Scyphozoa
jellyfish!
- medusa is dominate
- polyp is reduced
This type of cnidarians is polyp dominate with no medusa
anothozoa
Hydra live in
freshwater
do Hydra have a medusa stage?
no.
how do hydra move?
by gliding, somersaulting or floating
what do the tentacles of hydra contain?
cnidocytes
how long are the hydra tenatcles?
supa long
example of scyphozoa
JELLYFISH
what do jellyfish feed on?
larvae and zooplankton
who eats jellyfish?
leatherback turtle
Cassiopeia is known as the
upside down ejlly
what can cassiopeia tolerate?
low O2 conditions
where do cassiopeia get its o2 and nutrients?
from symbionts
anthozoa are known as
flower animals
example of anthozoa
sea anemones
how do sea anemones protect themselves?
retracting their tentacles
what animal do sea anemones have a (+/+) relationship with?
anemone fish and shrimp
coral bleaching
stress response is due to a variety of factors
- incresaing water temperature
- increasing UV Radiation
- pollution
- disease (bacteria)
Platyhelminthes
bilateria
what does the blastopore develop into in Platyhelminthes
mouths!
Platyhelminthes have
anterior brain
Platyhelminthes have
ventral nere cord
Platyhelminthes are
protosomes
Platyhelminthes are
triploblastic
How many species of flatworms are there?
25,000
how do flatworms move?
by cilia
where is the mouth in flatworms?
in the middle
how do flatworms get oxygen?
everywhere because their bodies are so flat that oxygen can’t get anywhere through diffusion (same for CO2)
do flatworms have a respiratory system?
no.
do flatworms have a circulatory system?
no.
Do flatworms have a digestive system?
no. they just get nutrients through their skin.
What is cephalization linked to?
directed movement
what is cephalization
concentration of neurons and sensory structures at the anterior end
what kind of symmetry do cephalization have?
bilateral symmetry
Turbellaria’s anterior end will always develop into a …
head
how do turbellaria reproduce?
asexually by fission AND sexually
A species of monogenea is
an ectoparasite
ectoparasites are known as
flat bodies with suckers
- flukes or fish gills
Trematoda cause
diseases that rarely lead to death but can damage internal organs and impair growth and development in children
an example of a cestoda is a
tape worm
where do tapeworms live?
intestines of vertebrates
do tapeworms have mouths?
no
what system do tapeworms not have?
digestive
