porifera and cnidaria Flashcards
what group are the phylum porifera in?
the basil group (earlier lineage to break away from the common ancestor)
what animal does the phylum porifera refer to?
sponges!
what are some characteristics of sponges?
- they have pores
- most abundant animal in the ocean
- most are sessile (do not move around), only the larvae move
what is the morphology of a sponge?
- no tissues or organs (no gut, muscles, nerves)
- some cells have specialized functions
- spicules (their version of a skeleton) give them structural support
- some sponges have only tough collagen-protein network for support
why are sponges considered to not have tissue even though some cells have a specialized function?
their ‘tissue’ is just a collection of cells, there is no separation from a membrane
in sponges, water gets pumped into _________ and it traps food
coenocytes
what are the two cells of the porifera?
choanocyte and mesophyll
what feeding process do sponges undergo?
filter feeding - suspension feeding
at the base of the choanocyte, food particles are engulfed by?
phagocytosis!
what is the function of the amoebocytes in filter feeding?
amoebocytes are fixed, and can move throughout the mesophyll taking food wherever is needed
what are some reproductive qualities of sponges?
- most sponges are hermaphroditic (possess male and female organs)
- sequential - can be simultaneously male and female, or switch from male to female
- they do not have ovaries or testes
how do egg cells arise in sponges?
from modified amoebocytes
how do sperm cells arise in sponges?
from modified choanocytes
do they use external or internal fertilization?
mostly internal
how do sponges reproduce?
- release of flagellated modified choanocyte (sperm)
- fertilizes amoebocytes in the mesophyll
- becomes a free-swimming larva
adult sponges are sessile, except for which stage?
ciliated larval stage
why are sponges important?
- they are filter feeders that clean the water
- many sponges have symbiotic relationships with single-celled algae and other organisms - mutualistic
what are some characteristics of animals in the phylum cnidaria?
- eumetazoa - true, differentiated tissues
- most have radial symmetry
- diploblastic - endoderm and ectoderm
- organs - collection of tissues specialized for different tasks
what animals does the phylum cnidaria encompass?
jellyfish, hydra, sea anemones, coral
what are the twos forms of cnidaria?
medusa and polyp
what are some characteristic of the medusa?
motile form
oral end downwards (mouth/anus)
moves freely through water through the hydrostatic skeleton (compressed muscles against cavity provides mobility)
have tentacles
what are some characteristics of the polyp?
sedentary (sessile)
oral end upwards (mouth/anus)
attached to a substrate (rock, coral)
have tentacles
the polyp and medusa body forms have a gastrovascular cavity, not a?
coelom!
are cnidarians omnivores, carnivores or herbivores?
carnivores
cnidarians have specialized cells called?
cnidocyte
what is the function of the cnidocyte?
a specialized cell for capturing prey
each cnidocyte contains?
a very complex endocellular structure
what is the most common type of endocellular structure?
nematocyst
how do cnidarian and cnidocytes capture prey?
- trigger spine of cnidocyte is touch-sensitive
- nematocyst shoots out
- others may be sticky, stabbing or poison tipped
- the prey is digested in the gastrovascular cavity
- nutrients is absorbed by nearby cells
what are reefs constructed by?
corals that provide shelter and food for many marine species
what are zooplankton?
tiny animals drifting in the water
what is the life cycle of hydrozoan obelia?
- polyp (feeding stage) turns into reproductive stage (medusa)
- medusa buds off and sometimes forms a motile medusa stage
- within the medusa there are gonads that make gametes through meiosis
- produce egg and sperm, fertilized, becomes a zygote and then larva
- once larva settles down somewhere, it returns to the polyp stage
(NOTE: not all form medusa)
