Week 3 Flashcards
opisthokonta
single posterior flagellum (when present)
fungi, choanoflagellates, animals
choanoflagellates
sister group to animals, very similar to collar cells in sponges
what surrounds the flagellum in opisthokonta
collar of microvilli
what does the beating of flagellum in opisthokonta do?
moves water through collar where food particles are filtered and collected
who shares a more recent common ancestor with the metazoa than the rest of the opisthokonta
choanoflagellates
what confirmed sponges are the earliest branch of the animal tree?
molecular phylogenetics
what happened when sponge genome was sequenced?
they are very similar t o other animals
what does sponge genome show evidence of?
all animals are descended from common ancestor of sponges and humans
what are the core building blocks of multicellular organisms?
cell specification
cell adhesion
self recognition
what is present in sponges?
all the core building blocks for complex multicellular organisms
what can sponges be used to study?
the origin of cancer
what does multicellularity go hand in hand with
cancer
what genes lead to cancer by their disruption
genes that regulate cell cooperation and division
where are the same genes that lead to cancer found?
sponges
Metazoa
waht makes something an animal?
motile, multicellular, heterotrophic eukaryotes ingest nutrient lack cell walls store carbs as glycogen characteristic development
glycogen
storage of glucose in animals
characteristic development in animals
generally go through blastula stage, with few characteristics development patterns that lead to different animal body plans
2 major early evolutionary branches of metazoa (animals)
1- parazoans
2- eumetazoans
parazoans
“beside animals”
no true tissues
collection of cells, no tissue-level organization
example of parazoans
sponges
eumetazoans
“true animals” have distinct, specialized tissues
example of eumetazoans
anything else
what sets parazoans from colonial protists
differentiated cells (true mulicellularity)
sponges
assemblege of cells in extracellular matrix
what evidence showed that sponges were animals
moleular evedience, tells us we share a common ancestor with other animals
what clade has the most of the major animal groups
eumetazoa
Phylum Porifera
9,000 species, all aquatic "pore bearing" cellular level of organization no stomach adults are sessile, larva is motile generally asymmetric
cellular organization
cells suspended in matrix, somewhat independent, collection of cells embedded in mesohyl
how does digestion occur in Phylum Porifera?
digestion is intracellular
what does Porifera rely on water currents for?
to bring food and oxygen, and to remove waste
can porifera form relationships?
yest with other species such at crabs and corals
does porifera have natural enemies?
no have few
3 advantages of multicellular organisms
allows cell specialization, can function more efficiently
allows increase in size, can escape predation
allows for more elaborate shapes
3 disadvantages of multicellular organisms
with specialized cells, how to tell self from non-self?
can’t fit in smaller places
as you get bigger diffusion becomes less efficient to transport nutrients and waste
what is something sponges can only do?
be split apart and reform together
what are cells suspended in sponges
mesohyl
4 cells in sponges
pinacocytes
porocytes
choanocytes
archaeocytes
pinacocytes
similar to epithelial cell, thin and flat, cover surface
are pinococytes considered true tissue?
no because they do not rest on basal membrane
porocytes
flagellum surrounded by collar of microvilli
choanocytes
flagellum by collar of microvilli
achaeocyctes
main function is to receive food particles and digest
what can archaeocytes do?
differentiate into other types
sclerocytes
spongocytes
collencytes
sclerocytes
spicules
spongocytes
spongin
collencytes
collagen
3 organization shcemes of sponges
1- asconoid
2- syconoid
3- leuconoid
asconoid
flaggellated spongocoel, only found in Calcarea
scaling is limited
syconoid
flagellated canals, only in Calcarea
more efficient but still can’t get very big
leuconoid
flagellated chambers
can get fairly large
what is most common orginizational scheme of sponges
leuconoid
what happens to number of choanocytes when volume increases
increases
what kind a feeder are sponges?
filter feeders
how does filter feeding work?
ostia and oscula
pumps huge volumes of water through chambers in bodies to catch food particles (and carry waste away)
food acqusition in porifera
water flows through canals/chambers, causes by choanocytes, water flows through mesh and food particles get stuck, moved down to cell body and phagocytized
do sponges have organs?
no
how does respiration and excretion occur?
diffusion
what do sponges rely on for all life processes
movement of water
how much water do sponges filter each day?
thousands of liters
sponge symbioses
form relationships with other species such as crabs and corals
sponge reproduction
can be sexual or asexual
sexual reproduction in sponges
monoecious, release sperm into water
free-swimming paranchymula larvae changes into sessile adult
flagellated ball of cells settles down and forms a sac, flagellated cells migrate to interior to form choanocytes
asexual reproduction in sponges
fragmentation or budding, or gremmules
gemmules
dormant masses of archaeocytes, (like a spore)
are marine sponges a rich source of bioactive compounds?
yes
4 classes of sponges
homoscleromorpha
calcarea
demospongiae
hexactinellida
homoscleromorpha
thin encrusting sponges with simple silaceous spicules (or none), cells have true basement membrane (incipient tissue)
tend to live in cyrptic habitats so often over looked
more common near shore, can live in deeper water
calcarea
spicules made of calcium carbonate, tend to be small, simpler (tube or vase shaped)
can be any body shape
demospongiae
silica (glass like substance) or organic spongin (collagen) or both, bath sponges only have spongin
larger species, relatively complex body types
some freshwater species
what class of sponges makes up 80% of all sponges
demospongia
hexactinellida
silica spicules, “glass sponges”, more open shape, tend to live in deep ocean
may have syncytial bodes
how many rays foes a hexactinellida spicules have?
6
synctyial body
many nuclei within a single very large cell
what do spicules often do in Class Hexactinellida
fuse together, giving more rigidity
protoplasmic
single celled eukaryote
developmental biology
study of irreversible events from zygote to death
what do all animals share
the same fundamental development pattern for the first several divisions only
what divisions do all animals have
fertilization
zygote
cleavage
what are the cleavage patterns
no cleavage, spiral, radial
blastula
hollow mass of cells
blastoderm
gives rise to other tissue types
“first tissue”
blastocoel
cavity of blastula
“first cavity”
gastrulation
some surface cells move inward
induced cell differentiate
cell differentiation
acquire new characters via differential gene expression
what does the movement of cell inwards create
gastrocoel
what is the gastrocoel
future gut cavity
during gastrulation what occurs
new embryonic tissues form
diploblast
endoderm
ectoderm
triploblast
endoderm
mesoderm
ectoderm
1st major branch within metazoa
parazoa and eumetazoa
when does cleavages stop
until there is a hollow ball of cells
what happens first during gastrulation
1st endoderm and ectoderm differentiate
2nd major branch of metazoa
diploblastic and triploblastic bilateria
symmetry in animals
spherical
radial
bilateral
spherical symmetry
protozoa
radial
radiata (sea stars, urchins)
diploblast
good for sessile and free-floating animals because you encounter your environment from all directions
bilateral
most animal groups
triploblasts
what type of secondarily can some animals become
radially symmetric
radiate characteristics
Cnidaria and Ctenophora
primary radial or biradial symmetry
tissue level of organization
diploblastic
what does ectoderm develop into
epidermis
what does endoderm develop into
gastrodermis
eumetazoa
true tissue cells, connected by junctions and bound to basal lumina, leads to effective subcompartmentalizaiton
cnido
nettle
Phylum Cnidaria
10,000 species mostly marine solitary or colonial lifestyle planula larva tentacles comtaining cnidocytes with cnidae
planula larva
ciliated, flattened, free swimming
cnidocytes
cell
cnidae
organelle within cnidocytes
most common cnidae
nematocysts
nematocysts
stinging organelle
what have Cnidarians got on poriferans
true germ layers (diploblasitc)
nervous system (nerve net)
gastrovascular cavity with one opening (extracellular digestion)
primitive muscular system with locomotion
sense organs
statocysts
ocelli
statocysts
sense balance/ equilibrium
do Cnidarians have true muscles
no, they don’t have mesoderm
what can contract body/tentacles
myofibrils in epitheliomuscular cells
what does the Cnidarian primitive muscular system allow
for them to be more active can search for food
complexity of Cnidarians
true tissues gastrovascular cavity epidermis endodermal gastrodermis mesoglea mostly water
2 body forms of Cnidaria
medusa
polyp
medusa
motile
polyp
sessile
can form colonies
what came first polyp or medusa
believed polyp then medusa
circular myofibrils in gastrodermis
longitudinal myofibrils in epidermis, permits expansion and contraction with hydrostatic skeleton
what does extra mesoglea do in medusa
stiffens body and provides resistance
where is a nematocysts housed
in a cnidocyte
what covers a nematocyts
by an operculum
operculum
cover/flap
what triggers a nematocysts
cnidocil
cnidocil
modified cilium
when a nematocyt is fired can it be reloaded
no, cell is reabsorbed and replaced
what happens when a nematocyt contacts with prey/threat
threadlike filament injects venom
volvents
like a lasso that wrap around and grab
glutinants
sticky stuff
nematocyst firing
high osmotic pressure inside cnidocyte, when triggered permeability changes, water rushes in and forces nematocyst out
nematocyst everted in spiral fahsion
spins like a rifle bullet; barbs may hold it in prey’s tissue
gastrovascular cavity
a single opening cavity
capture prey and insert into mouth, start digestion extracellularly with enzymes, finish with intracellular digestion
shortcomings of gastrovascular cavity in cnidarians
sequential breakdown not possible
can’t start a new meal
what else does the gastrovascular cavity serve for
respiratory, circulatory, and excretory functions
how do cnidarians respond to stimulus
nerve net
how do nerve nets work in cnidarians
they have 2 nets that are interconnected (gastrodermal, epidermal)
it has 2 way transmission
synapses with sensory cells, epitheliomuscular cells, and nematocysts
why is a nerve net advantageous to a cnidarian?
they can sense their environment
Class Hydrozoa characteristics
3600 species
freshwater & marine
solitary or colonial
generally asexual polyps with sexual medusae
how do the 2 body forms of medusa and polyp work in the class Hydrozoa
they can have both, they can have just one body form, but most are polyp dominated
what can a group of class hydrozoa do when only polyp form
reproduce asexually and sexually
what can a group of class hydrozoa do when they are medusa form only
generally only reproduce sexually
what is a common genus of class hydrozoa
hydra
where do fresh water species of genus hydra live
underneath lily pads and leaves
what do freshwater species of genus hydra feed on
small crustaceans and worms
what body form is the genus hydra of class hydrozoa
they are polyp only
how do the genus hydra of class hydrozoa move
mostly sessile but can move by somersaulting
how does the genus hydra of class hydrozoa reproduce
asexual reproduction via budding
sexual reproduction in autumn
gonads form on surface of body, produce tough encapsulated embryo that hatches in spring
genus hydratinia what do they do with their buds
they do not detach but form a interconnected colony in only polyp form
what does some genus hydratinia have
specialized polyps
gastrozooids
dactylozooids
gonozooids
gastrozooids
for feeding
dactylozooids
defense
gonozooids
reproduction
what does a colonial form of genus hydratinia share
a gastrovascular cavity
stolon
root for attachment to substrate
hydranth
gastrozooid
gonangium
gonozooid
what is a good example of colonial hydrozoan
genus obelia
what is the life cycle of genus obelia of class hydrozoan
alternates between medusa and polyp stages
how does reproduction occur in genus obelia
asexual in polyp- buds don’t detach and form part of colony
can differentiate into different types
sexual reproduction in medusa- release egg and sperm, develops planula larva
what is the genus physalia
not a jellyfish
are siphonophore
siphonophore
floating colonial polyps, made up of different zooids
are the stings of the genus physalia painful
yes but not deadly
how do you combat a sting from the genus physalia
vinegar and heat
class scyphozoa characteristics
“true jellies”
200 species
marine, solitary, polyp stage reduced
mesoglea
what body form is class scyphozoa mostly
medusa
mesoglea in class scyphozoa
sometimes has cells and usually has elastic fibers used to provide resistance when swimming
genus aurelia of class scyphozoa
“moon jellies”
polyp medusa alternation but medusa dominated
seperate sexes
extumbrella
dome part of genus aurelia
medusa form of genus aurelia
extumbrella and 4 oral lobes/arms with mouth in center
what is it like inside of the medusa form of genus aurelia
4 gastric pouches which connect to radial/ring canal system for circulating nutrients, pouches also contain gonads
how does reproduction occur in genus aurelia
planula develops into scyphistoma, then strobila, then strobilation to produce more medusae
class Cubozoa characteristics
“box jellies”
40 species
medusa form dominant
active predators
what helps class cubozoa be active predators
strong swimmers and potent venom
twitch tentacles to attract fish and actively attack them
what does class cubozoa have
photoreceptors
rhopalium
cluster of sensory structures with statocysts, ocelli and lensed eyes
do some complex, image forming”true” eyes found in rhopalium of some cubozoans
yes
where does good images form
behind the retina
what do the eye of cubozoans have
underfocused and will miss fine details
focused on large scale features of environment
class Anthozoa characteristics
6,000 species all marine polyp only, medusa absent reproduce sexually or asexually anemones and corals
what is the largest group that contains most of the species of phylum cnidaria
class anthozoa
what forms of the coral surface in class anthozoa
sheet of living tissue that connects all the gastrovascular cavities
how does eating occur in class anthozoa
during day photosynthesis by symbiotic algae
at night feeding of polyps on suspended plankton
what are sea anemones compared to other polyp forms
larger and heavier
are sea anemones carnivorous
yes, eat things like fish
what strengthens body walls and increases surface area for digestion and absorption
septae
siphonglyph
in corners of mouth create water currents directed into the pharynx to bring in oxygen and remove waste
do sea anemones move
no mostly sedentary but can close mouth and use hydrostatic skeleton to “swim”
class antozoa and mutualism
mucus produced on clownfish allows them to live in sea anemones without getting stung
fish get protection and some food, anemone gets protection and nutrients form waste
pom-pom crabs carries anemones around in its claws for defense and possibly to stun prey, anemone gets transported and can capture more food
similar on hermit crabs shells, will remove sea anemone from old shell and put it on their new shells
coral reefs
large structures made of the calcium carbonate secretions of some anthozoans
how are coral reefs built
corals convert calcium and carbonate ions form seawater into limestone
what layer of coral reefs is living
only the top/outer layer
the rest of the layers are calcium carbonate secretions
hexamerous
6 fold body symmetry
essential mutualism in coral reefs
reef building coral and endosymbiotic zooxanthellae
zooxanthellae gives food and O2 to host, recycle P&N, and enhance CaCO3 depostion, provide color
coral gives nutrients and shelter, get enough energy to secrete calcium carbonate skeleton
are zooxathellae picky
yes they need it warm but not too warm, low turbidity, and just right salinity
coral bleaching and global warming
increased temperatures damages photosynthetic pathway, releasing harmful oxidants.
diffuse into coral tissue, harm mutualism, and algae leave or are expelled by immune response of coral
can coral survive bleaching
yes, but not for long
also makes it harder to outcompete algae
what is leading to coral bleaching
increased co2
overfishing
eutophication
eutophication
adds nutrients
