3: Porifera, Cnidaria, and Ctenophora Flashcards
phylum:
- sessile, aquatic filter feeders
- rely on water for feeding, gas exchange, excretion
sponges
large chamber in center of sponge
spongocoel
large opening where water exits the spongocoel
osculum
jelly-like substance that separates the outer layer of cells from the choanocytes
mesohyl
mineralized structures that make up sponge’s “skeleton”
spongin & spicules
important in distinguishing different classes of sponge
spicules
- flagellated cells surrounded by a collar
- used for feeding and reproduction
choanocytes
- solitary or colonial aquatic eukaryotes
- similar in structure to choanocytes
choanoflagellates
amoeboid cells that move in the mesohyl and perform several functions
archaeocytes
specialized archaeocyte: secrete spicules
sclerocytes
specialized archaeocyte: secrete spongin
spongocytes
- thin, flat cells that form the pinacoderm
- closest in form to true tissues
- can ingest particles through phagocytosis and regulate the sponge’s SA
pinacocytes
sponge digestion occurs…
intracellularly
4 classes of sponge
- calcarea
- hexactinellida
- demospongiae
- homoscleromorpha
sponge class:
- spicules made up of calcium carbonate; usually needle shaped; 3-4 rays
- small
- entirely marine
calcarea
sponge class:
- glass sponges
- skeleton composed of 6-rayed siliceous spicules
- often cylindrical or funnel shaped
- all marine; prefer deep water
hexactinellida
- largest group of sponges
- spicules siliceous but not 6-rayed
- majority marine; one freshwater family
- varied shapes
demospongiae
sponge class:
- pinacoderm has a basal lamina
- some lack spicules entirely
homoscleromorpha
phylum:
- radially symmetric animals
- nearly all marine
- contains cnidocytes
- have true tissue; diploblastic; don’t contain true organs
- reproduce sexually/asexually
cnidaria
specialized stinging cells in cnidarians
cnidocytes
cnidarian body plan:
- adapted for sedentary life
- most have tubular bodies
- may reproduce asexually
polyp
polyp in colonial cnidarians for feeding
gastrozooids
polyp in colonial cnidarians for reproduction
gonozooids
Cnidaria dimorphism:
- usually free-swimming
- bell/umbrella shaped bodies
- have sensory structures for orientation & light reception
medusa
Body plan:
- larva that cnidaria zygote develops into
- attaches to a substrate and then metamorphoses into a polyp
planula
- stinging cells concentrated around the mouth and tentacles
- produce organelles known as cnidae
cnidocytes
cnidae that administer toxins for feeding and defense
nematocysts
serves as trigger in all cnidarians excepts anthozoa
cnidocil
- incomplete gut
- often branched/ divided w septa
- opening surrounded by tentacles
- shared in colonial cnidarians
gastrovascular cavity
outer epidermis and inner gastrodermis w mesoglea in between (cnidarians)
body wall
jelly-like extracellular matrix in cnidarians
mesoglea
scattered network where nerve cells are organized in cnidarian simple nervous system
nerve net
groups of nerves that house sensory receptors
rhopalia
6 classes of cnidarians
- hydrozoa
- scyphozoa
- staurozoa
- myxozoa
- cubozoa
- anthozoa
cnidaria class:
- solitary or colonial organisms w a dominant polyp form
- ex: hydra, portuguese man o’ war
hydrozoa (hydras)
hydra; can revert back to polyp stage of their development in response to damage or starvation (transdifferentiation)
turritopsis
cnidaria class:
- true jellyfishes
- dominant medusa form w a bell-like shape
- margin of bell has 8 notches w rhopalia
- “cup animals”
scyphozoa
cnidaria class:
- ex: box jellyfish
- dominant medusa stage that is box-shaped rather than bell-shaped
- each corner of umbrella has a tentacle/s hanging from a pedalium
- “box animals”
cubozoa
small and highly venomous box jellyfish
irukandji jellyfish
cnidaria class:
- flower-like polyps
- don’t have medusa stage
- can be solitary or colonial
- “flower animals”
anthozoa
3 subclasses of anthozoa
- hexacorallia
- ceriantipatharia
- octocorallia
anthozoa subclass:
- contains sea anemones and hard/true corals
- hexamerous body plan
hexacorallia
From hexacorallia:
- large polyps
- gastrovascular cavity is divided into 6 chambers by 6 pairs of mesenteries
- form mutualistic relationships w several organisms
sea anemonies (actinaria)
From hexacorallia:
- anemone-like polyps living in a calcium carbonate exoskeleton
- epidermis at base secretes exoskeleton
true corals (scleractinia)
anthozoa subclass:
- unpaired mesenteries
- can be solitary (tube anemones) or colonial (black corals)
subclass ceriantipatharia
anthozoa subclass:
- soft and gorgonian corals
- octomerous body plan
- all colonial
octocorallia
series of tubes that connect gastrovascular cavities of each polyp
solenia
- reef-building corals
- require warm temps, light, high salinity
hermatypic
large formations of limestone in shallow, tropical seas deposited by organisms over thousands of years
coral reefs
mutualistic dinoflagellates that need light
zooxanthellae
occurs when the loss of zooxanthellae turns corals white and brittle
coral bleaching
phylum:
- comb jellies
- have 8 rows of comblike plates of cilia for movement
- complete gut
- entirely marine
- mostly monoecious
- similar nerve network to cnidarians
cteneophores
