Quiz 6- poriferans, cnidarians, annelids, molluscs Flashcards
Use your understanding of poriferan biology to assemble a marine sponge, and identify the major cells, structures and forms.
pinacocytes
mesenchyme
archeocyte cells
choanocytes
flagellum and microvilli collar
pinacocytes
exterior “skin” cells of sponges- some become porocytes
mesenchyme
jelly-like middle layer of sponges
***made of archeocyte cells: move around in mesohyl- reproduce, transport + store food, secrete spicules
spicules
mesenchyme/ archeocyte cells called SCLEROCYTES secrete skeletal elements called spicules that can be made of CaCO3, silica, or spongin
variable shapes
choanocytes
in sponges
flagellum and microvilli collar
line inner layer of sponges
drive water movement in thru pores for filter feeding
Explain how water & nutrients move through, and are utilized by, poriferans.
water flows in thru porocytes + out thru osculum opening
brings in food + o2, removes wastes
3 major porifera body forms
ascon
sycon
leucon
all have pores, choanocytes, and at least one osculum
major difference btwn ascon + sycon sponges
sycon has folds called radial canals that are lined with choanocytes
ascon are simplest, LEAST common
porocytes called ostia
Differentiate between sexual and asexual reproduction in Poriferans.
most monoecious- (both sexes on 1 individual)
do NOT self fertilize bc eggs and sperm are ready at different times
sperm cell is a modified choanocyte- engulfed by a choanocyte on egg, fertilized, planktonic larva, settles/attaches to substrate + develops
leucon sponge
no spongocoel cavity
pores lead water thru choanocyte chambers
several osculi openings
four major classes of Cnidarians.
anthozoans
scyphozoans
cubazoans
hydrozoans
gen chars of cnidarians
nettles!
have 2 tissue layers:
epidermis and gastrodermis
mesoglea
radial symmetry
blind gut
well formed digestive system
often dioecious
nervous system
mesoglea
in cnidarians
jelly-like substance btwn 2 tissue layers (epidermis + gastrodermis)
cnidarian digestion
extracellular
dioecious
separate sexes
like cnidarians (generally)
cnidarian excretion
diffusion
cnidarian nervous system
network of nerve cells
major cnidarian stages
sessile polyp
stinging medusa
both have stinging cells + tentacles
anthozoans
anemones, corals, + sea fans
CARNIVOROUS
(may have symbiotic zooxanthellae)- supplement diet
no medusa stage
solitary or colonial
stony corals excrete calcium carbonate
anthozoan stages
polyps produce gametes that develop into swimming planular larvae that then settle + develop
scyphozoans
true jellies!
carnivorous
outside of body covered in sensory structures
move via muscle contraction (rings)
scyphozoan stages + life cycle
short benthic polyp stage, long planktonic stage
medusae shed gametes that develop into (planular) larvae then develop benthic stage
benthic stage undergoes STROBILATION
strobilation
in true jellies (scyphozoans)
during benthic stage
little developing ephyra pop off the end + swim off!
smaller ephyra develop into larger medusae
cubozoans
box jellies!!
carnivorous
well developed eyes
unusually strong swimmers compared to other cnidarians
chironex fleckeri
australian box jelly/sea wasp
weirdly do not develop benthic stages in reefs- only in estuaries of rivers on undersides of stones
cubozoan life cycle stages
benthic polyp stage, medusae
hydrozoans
simplest cnidarians
benthic colony + medusa stages
planktonic hydrozoa- eg: velella velella + portuguese man’o’war (spend most of life in medusa stage)
also hydrozoans that spend most of their life in benthic stage
hydrozoan benthic colony stage
polymorphic- feeding and reproductive cells all attached to one another
***called gastrozooids and gonozooids
Explain how cnidocytes function, and be able to label their major structures (nematocysts, thread, barb, cnidocil).
nematocysts- actual stinging systems (organelles)
barb holds thread
cnidocil- hair-like projection
How does scyphozoan reproduction differ from hydrozoan reproduction?
scyphozoans have individual benthic polyps while hydrozoans have colonies
hydrozoan colonies have specialized gastro- + gonozooids
benthic scyphozoan polyps undergo strobilation
both have medusae