Ch 6-7: Phylum Cnidaria Flashcards
(67 cards)
1
Q
how many epithelial layers do cnidarians have?
A
2: outer epidermus and inner gastrodermus/endodermus - diploblastic
2
Q
what do the cells in the epithelia do? (5)
A
- communication
- movement
- digestion
- internal transport
- reproduction
3
Q
what is the connective tissue in cnidaria?
A
jellylike mesoglea
4
Q
do cnidarians have distinct muscle and nervous tissue?
A
some do
5
Q
what type of symmetry do cnidarians have?
A
superficially, radial
- aboral and oral sides
6
Q
what are the two types of body forms cnidarians have?
A
- polyp
2. medusa
7
Q
are clonal colonies of medusae and polyps common?
A
yes
8
Q
polyp properties (2)
A
- asexual
- benthic
9
Q
medusa properties (2)
A
- sexual
- free-swimming
10
Q
what type of larva do they have?
A
planktonic (planula)
11
Q
what does cnidarians gv cavity allow for?
A
more extracellular digestion
12
Q
type of diet
A
carniverous
13
Q
what do their tentacles do? (2)
A
catch food and defend
14
Q
what do cnidocytes contain?
A
nematocysts (triggered bags of dischargeable threads)
15
Q
do cnidarians have a brain?
A
no; may have ganglia
16
Q
what do the light sensitive cells on their epithelium do? (2)
A
- gather info
- send out commands
17
Q
where are cnidarians statosysts located?
A
btwn tentacle bases
18
Q
what is the primary function of bell pulsation?
A
food collection
19
Q
how do cnidarians respire and excrete?
A
diffusion
20
Q
4 anthozoan features
A
- no medusa stage
- thick mesoglea with many cells
- gv cavity divided by septa/mesenteries
- have siphonoglyphs
21
Q
anthozoan symmetry
A
bilateral
22
Q
how do anthozoans cnidocytes differ from those of other cnidarians?
A
no operculum and no trigger
23
Q
hexacorallia features (4)
A
- many tentacles
- 6 mesenteries
- 2 siphonoglyphs
- some colonial
24
Q
octacorallia features (4)
A
- tentacles in groups of 8
- 8 primary mesenteries
- 1 siphonoglyph
- almost all colonial
25
4 features of actiniaria (sea anenomes)
- use muscles and internal water as hydrostatic skeleton
- can change shape
- move via basal disc crawl
- some 'swim'
26
how do actiniaria asexually repro?
can cleave in half
27
how do actiniaria sexually repro? (4 steps)
1. gonads along mesenteries prod gametes
2. gametes ejected thru mouth
3. planula larvae
4. settle and turn into polyp
28
acrorhagi
bulges of body wall w/ many nematocysts
29
what is the function of acrorhagi?
territorial fights
30
Scleractinia features (3)
- colonial
- CaCo3 skeleton surrounds each polyp and extends along mesenteries
- some spp combine to form reefs, some are solitary
- mostly in shallow, clear, tropical water
31
how do corals eat?
- hunt at night
- prod mucus to help prey capture
- some purely carnivorous deepwater corals
- 90% of food prod by zooxanthellae
32
how are zooxanthellae acquired?
taken into vesicles via phagocytosis; can be expelled/lost (bleaching)
33
3 features of Octocorallia
- use chemicals to poison/discourage predators
- tentacles have tiny side-branches (pinnules)
- tolerant of enviro extremes than stony corals
34
what are Gorgonacea (sea plumes, fans, whips) skeleton made of?
protein; spicles of CaCO3
35
3 features of Pennatulacea (sea pens)
- colonies of different, specialized polyps
- CaCO3 spicules give support and colour
- usually in deeper water
36
polyp formation and function
- one polyp forms a central stalk and a root-like penduncle, other form side branches
- others collect food and carry nematosysts
37
3 ways sea pens can defend themselves?
- taste bad
- can withdraw into penduncle
- bioluminescence
38
what is unique about medusazoan DNA?
linear mitochondrial DNA
39
5 defining features of Scyphozoa
- thick mesoglea that may contain cells
- medusa most obvious part of life cycle
- medusa may have 4 mouth lobes as well as tentacles that contain nematocysts and extensions of the gv cavity
- 2 neuron networks; one for swimming, one for everything else
- special sensory organs called rhopalia along bell margin
40
what type of symmetry to scyphozoa have?
bilateral
41
what 3 things do rhopalia contain?
- statosysts
- ocelli
- chemosensory cells
42
5 features if Cubozoa
- 4 tentacles/clusters of them
- reduced bell opening for extra propulsion
- well-developed nerve net
- well-developed rhopalia
- potent nematocysts
43
what type of symmetry do Cubozoa have?
bilateral
44
where are Cubozoa most common?
near shore
45
Cubozoan eyes
- up to 6 eyes per rhopalium
- 4 have a lens and can form images
- may help avoid large obstacles
46
in their life history, what do Cubozoans NOT have?
strobilization
47
5 features of Staurozoa
- polyps have a stalk, bearing a 4 sided calyx
- 1-4cm
- no medusa stage
- attach to rocks, seaweed
- known as fossils
48
how many sets of tentacles to Staurozoa have?
8
49
where are Staurozoa most common?
- cold northern seas
| - near shore
50
4 stages of annual life cycle
1. m/f release eggs into water
2. eggs sink to bottom
3. larvae crawl along bottom
4. metamorphose into polyp
51
4 features of Class Hydrozoa
- thin mesoglea with no cells
- alternate btwn polyp and hydromedusa
- mostly small
- most morphologically diverse class
52
Gonionemus features (2)
- hydromedusa most commonly seen
| - nerve net and nerve ring at bell margin
53
life cycle of Gonionemus (5)
1. separate sexes perform open fert
2. planula larva
3. settles to the bottom
4. grows tentacles and mouth and becomes polyp
5. budding forms more polyps or hydromedusae
54
what is unique about Turritopsis?
does not die after sexual repro - can turn back into polyps
55
7 unique features of Hydra
- adapted to freshwater
- no hydromedusa stage
- no statocysts
- can retract into a blob
- has stretch receptors
- somatosensory cells on basal disc and tentacles
- can move towards light
56
what are 3 ways Hydra can move?
- basal disc crawl
- somersaulting
- detaching and being carried by the current
57
how do Hydra asexually repro?
when they are well fed, they bud new polyps
58
how do Hydra sexually repro?
polyps prod free-swimming sperm but hold onto their eggs
| - release a gastrula that 'hatches' into a polyp
59
which stages are usually present in colonial Hydroids?
polyp and hydromedusa stages
60
how are new polyps produced?
via budding
- stay attached to become the colony
- called zooids
61
zooid specialization (2)
- gastrozooids eat
| - gonozooids prod hydromedusae for sexual repro
62
colonial structure of Hydroids
- share gv and food
- zooids connected by stalk
- colony is rooted by a stolon
- stalks and stolons encased by common perisac
63
what is a perisac made of?
polysaccharides and proteins
64
Siphonofore characteristics (2)
- colonies of polyps and medusae
| - medusae may jet propel the colony or may act as sails
65
3 types of zooids in Portuguese man of war polyps
- gastrozooids
- gonozooids
- dactylozooids
66
Port man of war tentacles length
up to 20m
67
Myxozoa characteristics (3)
- much reduced body complexity
- parasites of fish and annelids
- consist of only a few cells
