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