Transcript Porifera, Cnidarians, and Ctenophores

Rupp
Bio II
Invertebrates
 No backbone
 No shared characteristics
 12 phyla
 One million species
 97% of all animals
Porifera Background
 Sponges
 No gastrula stage
 No true tissues or
organs
 Approx. 10,000 species,
only 150 are freshwater
 Sessile
 1cm long to 2m in
diameter
Porifera Body Plan
 Two layers
 Closed at bottom, open at top, and hollow
 Collar cells, pores, osculum
Porifera Body Plan Continued
Three Types of Sponges
 Those made with spongin, which is a support fiber
 Those made with spicules, which are hard particles of
calcium carbonate and silicon dioxide
 Combination of spongin and spicules
Feeding
 Filter feeders
 Food sources
 Bacteria
 Protozoans
 Algae
 Organic matter
 Collar cells to
amoebocytes to water to
osculum
Reproduction—asexual
Budding
Gemmulation
 Offspring forms as an
 A cyst-like reproductive unit
outgrowth of the parent
 If the bud does not separate a
colony will form
formed in freshwater sponges
 Formed in summer or fall and
can overwinter
 Like a seed or spore
Reproduction—asexual con’t.
Reproduction—asexual con’t.
 Regeneration—
restoration or new
growth of tissue that
may have been injured or
lost
Reproduction—sexual
 Sperm are pulled in by the collar cells
 Collar cells give the sperm to the amoebocytes
 Amoebocytes deliver sperm to the eggs
 Fertilization
 Larva form
 Larva are releases into the environment through the
osculum
 Larva will develop into adults after cellular
reorganization—metamorphosis
Reproduction—sexual con’t.
 Some sponges are hermaphrodites
 Self-fertilization is rare
 Cross-fertilization is productive for genetic variety
 All can produce eggs, therefore greater offspring
numbers
 Some species maintain gender
Cnidarians and Ctenophores
 Radially symmetrical invertebrates
 Have tissues and a few simple organs
 Aquatic and most are marine
Cnidarians and Ctenophores—
structure and function
 Two shapes
 Vase or polyp which is
sessile
 Bell or medusa which is
mobile
 Two layer construction
 Epidermis
 Gastrodermis
 Mesoglea—jelly-like layer
between epidermis and
gastrodermis
 Gastrovascular cavity
 Tentacles around mouth
Hydra
Which type of body structure
does this organism exhibit?
Jellyfish
Which type of body structure
does this organism exhibit?
Nay Nay’s
Handywork
National Zoo, Washington D. C.
Coral
Which type of body structure
does this organism exhibit?
Cnidarian and Ctenophore—
feeding and defense
 Cnidocytes—specialized
defense and prey capture cells
 Nematocysts—stinging cell
within the cnidocyte
 Located on tentacles
 Trigger present
 When triggered a filament
extends to deliver the sting,
poison, or wrap the intruder
 Prey captured, moved into
mouth, nutrients absorbed,
prey expelled through mouth
Cnidarians and Ctenophores—
nervous system
 Nerve net
 Stimulus-response
action—no thinking
 Entire body contracts
 Feeding and swimming
are coordinated by the
nerve net
 Stimulus to nerve net to
epidermis to contraction
Cnidarian classification
 Three classes
 Hydrozoans
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Only polyps
Only medusas
Alternate generations
Mixed colonies
 Scyphozoans
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Medusa
 Anthozoans

Polyps
Hydrozoans
 3700 species
 Typically marine and colonial
 Obelia
 Polyps on stalks
 Some feed, others reproduce
 Physalia
 Portuguese man-of-war
 Colony of medusas and polyps
 Gas-filled float
 Polyps


Feeding and digestions
Reproduction
 Huge numbers of cnidocytes
Hydrozoans—Hydra



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Very unique
Only polyps
Freshwater
Not colonial
Can be green due to
symbiotic relationship
with algae
 Capable of movement
 Gas bubble float
 Somersaulting
 Asexual reproduction—
budding in warm
weather
 Sexual reproduction—
cool fall weather triggers
gamete formation
 Hermaphroditic
 Male
 Female
Scyphozoans
 Name means “cup animals”
 Dominant form is the medusa
 Jellyfish
 2cm to 4 m in size
 Aurelia
 Alternation of generations
Anthozoans
 Name means “flower
animals”
 6100 marine species
 Anemones and corals
 Anemones
 Polyps
 Feed on fish
 Symbiotic relationship
with clown fish
 Corals
 Small colonial polyps
 Connect to each other
with CaCO3 skeletons
 Form reefs
 Tropical dwelling
 Symbiotic with algae for
extraction of calcium
from sea water,
therefore shallow living
Anthozoans
Anemones
Corals
Ctenophores
 Approximately 100 species
 Marine dwelling
 Colloblasts instead of
cnidocytes
 Comb-like rows of cilia
 Secrete a sticky substance
 Often called comb jellies
 Binds prey
 Cilia are used for
movement as opposed to
contractile swimming—
largest organisms to move
this way
 Located on two tentacles
 Apical organ at one end of
body allows a sense of
orientation in water—
nerves in apical organ
coordinate cilia
 Bioluminescent