lec 3 metazoa key characters Flashcards
metazoa
a phylogeny of kingdom animalia
what cellularity are protists?
almost always unicellular
what cellularity are fungi?
multicellular
what cellularity are plants and aimals
always multicellular
why is it hard to distinguish multicellular vs single celled
because of the continuum between them
how many times has multicellularity evolved
as many as 25 to as few as 13
what are the 5 criteria of multicellilarity
1) not viable as single cell
2) cells are interdependent
3)morphologically differentiated for different tasks
4) 2 or more cells work in a coordinated fashion on a common task
5) 2 or more layers of cells are present in organisms body
cillia vs flagella
cillia: shorted beat stiffly
flagella: long and beat undulating- more than one curve
symmetrical
animals can be split into similar halves along at least one axis of their body
asymmetrical
lack plane of symmetry
spherical symmetry
completely spherical shape and many planes of symmetry
where is spherical symmetry seen
a few protists
radial symmetry
body parts arranged radially around a central oral- aboral axis
where is radial symmetry seen most
some sponges, and some cnidarian polyps
Biradial symmetry
aboral axis but differentiation on the body. Means two planes of symmetry
where is biradial symmetry seen
most ctenophores
quadriradial symmetry
there are four planes of symmetry
where is quadriradial symmetry seen
cnidarian medusae
pentaradial symmetry
oral/ aboral axis and 5 planes of symmetry
where is pentaradial symmetry seen
echinoderms
bilateral symmetry
single anterior posterior plane divides body into mirrored left and right halves
where is bilateral symmetry seen
bilateria clade
mitotic binary fission
asexual reproduction
protists not metazoans
fragmentation
Where does it occur??
worm mfs splitting
sponges, many worm phyla
asexual
budding
where a bud results in independent individual or it remains attached.
asexual
attached buds result in
colony
animal colonies
multicellular organisms physically connected and are genetically identical.
sexual reproduction
involves fusion of two meiotically produced haploid cells (gametes) to form diploid zygote
egg
larger, non motile, made by females
sperm
smaller and motile, usually flagellated, made by males
yolk
nutritive material inside egg
isolecithal
egg have yolk particles distributed evenly through the cytoplasm
telolecithal
yolk concentrated towards one end of the egg
centrolecithal
yolk concentrated at centre of the cell
hermaphroditism
single individual can make both eggs and sperm
type of hermaphroditism where individual makes both ehhs and sperm at same time
simultaneous hermaphroditism
hermodaphroditism where eggs and sperm at seperate times in animals life
sequential hermaphroditism
parthenogenesis
females produce eggs that develop into offspring without being fertilized
word for when unfertilized haploid eggs develop into males and the fertilized ones develop to females
haplodiploid parthenogenesis
word for unfertilized diploids eggs develop to females and no males are produced
all-female parthenogenesis
ontogeny
process when individual transforms from single celled zygote to multi celled embryo and from that to reproductive adult
embryogenesis
patterns in the early stages of development
cleavage
the initial cell divisions of a zygote
how thoroughly blastomeres separate from eachother depends on the distribution of:
yolk in the egg
initial products of cleavage
blastomeres
holoblastic cleavage
involves complete separation of the blastomeres and occurs in isolecithal and lightly telolecithal eggs
meroblastic cleavage
involves incomplete separation of the blastomares and occurs in strongly telolecithal eggs bc cell membranes cant penetrate the dense yolk
radial cleavage
early cell divisions after the 5 cell stage stack the new blastomeres directly above the previous ones
spiral cleavage
new row of blastomeres is twisted slightly off centre
holoblastic cleavage results in
a hollow ball of cells
what does meroblastic cleavage result in?
a cap of cells lying on top of the yolk
true tissues
collection of simmilar cells, and a extracellular matrix, that arise from the same embryonic origin that together carry out a specific function
organs
formed by the same functional grouping together of multiple tissue samples
germ layers
embryonic tissue layers
diploblastic
taxa have only endoderm and ectoderm
triploblastic
have endoderm, ectoderm, and mesoderm
gastrulation
-initial formation of the embryonic tissue layers
-also forms the embryonic gut
embryo is a
gastrula
blind gut
incomplete gut
a mouth but no anus
what does the blastospore become
the mouth
protostome style development
mouth develops first
deuterostome style
mouth develops second
coelom
body cavity filled with fluid created by animal
are coeloms present in all triploblastic animals
no
aoelomate
no fluid filled body cavity
pseudocoelomate
fluid filled cavity is lined with mesoderm only on one side
schizocoely
hollowing out of soluid masses of mesoderm to form one or more coelomic cavities
enterocoely
out pocketing of mesoderm tissue associated with the gut walls
skeleton
array of elements that support the body of an organism and may also play role in movement
hydrostatic skeleton
fluid based skeleton
rigid internal skeleton
endoskeleton
rigid external skeleton
exoskeleton
what is oxygen used for?
respiration to get rid of CO2 and other wastes,
transport nutrients
how do extremely flat or small organism’s circulatory systems work?
diffusion
how do large organism’s circulatory systems work?
move water through their bodies
how do pseidocoelomates circulatory systems work
use fluid in their body cavities for internal transport
closed circulatory system
blood kept seperate from coelomic fluid in closed vessels
open circulatory system
blood and fluid in same cavity
fluid in open circ system called what
haemolymph
haemolymph flows through the
haemocoel
