porifera and cnidaria

Question 1

what group are the phylum porifera in?

Answer 1

the basil group (earlier lineage to break away from the common ancestor)

Question 2

what animal does the phylum porifera refer to?

Answer 2

sponges!

Question 3

what are some characteristics of sponges?

Answer 3

1. they have pores
2. most abundant animal in the ocean
3. most are sessile (do not move around), only the larvae move

Question 4

what is the morphology of a sponge?

Answer 4

1. no tissues or organs (no gut, muscles, nerves)
2. some cells have specialized functions
3. spicules (their version of a skeleton) give them structural support
4. some sponges have only tough collagen-protein network for support

Question 5

why are sponges considered to not have tissue even though some cells have a specialized function?

Answer 5

their ‘tissue’ is just a collection of cells, there is no separation from a membrane

Question 6

in sponges, water gets pumped into _________ and it traps food

Answer 6

coenocytes

Question 7

what are the two cells of the porifera?

Answer 7

choanocyte and mesophyll

Question 8

what feeding process do sponges undergo?

Answer 8

filter feeding - suspension feeding

Question 9

at the base of the choanocyte, food particles are engulfed by?

Answer 9

phagocytosis!

Question 10

what is the function of the amoebocytes in filter feeding?

Answer 10

amoebocytes are fixed, and can move throughout the mesophyll taking food wherever is needed

Question 11

what are some reproductive qualities of sponges?

Answer 11

1. most sponges are hermaphroditic (possess male and female organs)
2. sequential - can be simultaneously male and female, or switch from male to female
3. they do not have ovaries or testes

Question 12

how do egg cells arise in sponges?

Answer 12

from modified amoebocytes

Question 13

how do sperm cells arise in sponges?

Answer 13

from modified choanocytes

Question 14

do they use external or internal fertilization?

Answer 14

mostly internal

Question 15

how do sponges reproduce?

Answer 15

1. release of flagellated modified choanocyte (sperm)
2. fertilizes amoebocytes in the mesophyll
3. becomes a free-swimming larva

Question 16

adult sponges are sessile, except for which stage?

Answer 16

ciliated larval stage

Question 17

why are sponges important?

Answer 17

1. they are filter feeders that clean the water
2. many sponges have symbiotic relationships with single-celled algae and other organisms - mutualistic

Question 18

what are some characteristics of animals in the phylum cnidaria?

Answer 18

1. eumetazoa - true, differentiated tissues
2. most have radial symmetry
3. diploblastic - endoderm and ectoderm
4. organs - collection of tissues specialized for different tasks

Question 19

what animals does the phylum cnidaria encompass?

Answer 19

jellyfish, hydra, sea anemones, coral

Question 20

what are the twos forms of cnidaria?

Answer 20

medusa and polyp

Question 21

what are some characteristic of the medusa?

Answer 21

motile form
oral end downwards (mouth/anus)
moves freely through water through the hydrostatic skeleton (compressed muscles against cavity provides mobility)
have tentacles

Question 22

what are some characteristics of the polyp?

Answer 22

sedentary (sessile)
oral end upwards (mouth/anus)
attached to a substrate (rock, coral)
have tentacles

Question 23

the polyp and medusa body forms have a gastrovascular cavity, not a?

Answer 23

coelom!

Question 24

are cnidarians omnivores, carnivores or herbivores?

Answer 24

carnivores

Question 25

cnidarians have specialized cells called?

Answer 25

cnidocyte

Question 26

what is the function of the cnidocyte?

Answer 26

a specialized cell for capturing prey

Question 27

each cnidocyte contains?

Answer 27

a very complex endocellular structure

Question 28

what is the most common type of endocellular structure?

Answer 28

nematocyst

Question 29

how do cnidarian and cnidocytes capture prey?

Answer 29

1. trigger spine of cnidocyte is touch-sensitive 2. nematocyst shoots out 3. others may be sticky, stabbing or poison tipped 4. the prey is digested in the gastrovascular cavity 5. nutrients is absorbed by nearby cells

Question 30

what are reefs constructed by?

Answer 30

corals that provide shelter and food for many marine species

Question 31

what are zooplankton?

Answer 31

tiny animals drifting in the water

Question 32

what is the life cycle of hydrozoan obelia?

Answer 32

1. polyp (feeding stage) turns into reproductive stage (medusa) 2. medusa buds off and sometimes forms a motile medusa stage 3. within the medusa there are gonads that make gametes through meiosis 4. produce egg and sperm, fertilized, becomes a zygote and then larva 5. once larva settles down somewhere, it returns to the polyp stage (NOTE: not all form medusa)