Invertebrates
Invertebrate Characteristics
 Domain Eukarya; Kingdom Animalia
 Lack Backbone (vertebrae)
 Multi-cellular
 No cell wall
 Most have tissues- except for sponges
 Most are Symmetric
Phylum Porifera
 Porifera means: “Pore bearing”
 Symmetry:
Asymmetric
 Members: Sponges
Phylum Porifer

Skeleton:



Most made of flexible
protein called spongin
Some have a brittle
skeleton (needles)
called spicules
Flagellated cells
called choanocytes
that line the inside
Phylum Porifer

Method of Feeding (filter feeders):
Water enters by passing through
pores on the body wall (ostia).
Choanocytes trap tiny organisms
(algae & bacteria) in the water
1.
2.
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
3.
Choanocyte’s flagella draws water
down through the choanocytes
Food is ingested through
endocytosis
Waste is expelled from osculum
(opening at top)
Phylum Porifer

Physical Characteristics:



Sessile- attached & stay in
one place
Structures- Lack a nervous
system, circulatory system,
respiratory system, &
excretory organs
Reproduction:



Hermaphrodite
Budding and fragmentation
Can regenerate
Phylum Cnidaria
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

Cnidaria means: “Stinging Cells”
Symmetry: Radial
Members: Jelly fish, anemone, urchins, freshwater
hydra, flowerlike coral
Phylum Cnidaria

Method of Feeding:



Have stinging tentacles arranged
in circles around their mouths
(one body opening)
Cells have nematocysts
barbed harpoon that spears prey
Prey is brought to the cnidarian
mouth into the gut & broken
down
Phylum Cnidaria

Skeleton:

Two Shapes:

Vase shaped polyps &Umbrella shaped medusa
Phylum Cnidaria

Characteristics:


Sessile or floating
Systems:
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Reproduction:

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Have a simple nervous system (nerve net)
Lack blood vessels, respiratory system, & excretory organs
Hermaphrodite
Polyps can reproduce by budding
Can regenerate
Bell Work
How do organisms that belong
to Phylum Porifera differ from
those that belong to Phylum
Cnidaria?
Phylum Mollusca



Mollusca means: “soft bodied”
Symmetry: Bilateral
Members: three classes



Gastropods snails, slugs, conks
Bivalves clams, muscles, oysters
Cephalapods octopus, squid, nautilus
Phylum Mollusca

Method of Feeding



Gastropods tongue w/ curved teeth (scraping)
Bivalves gills (filter plants and bacteria)
Cephalapods tentacles and jaws
Phylum Mollusca
 Skeleton
 Gastropods shell
 Bivalves shell
 Cephalapods large beak with arms
Phylum Mollusca

Characteristics:


Sessile, moving, floating
Systems:

Have some form of nervous system



Have Circulatory system


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All have ganglia (mass of nerve cells)
Cephalopods have brains
Open system- blood not contained in vessels (most mollusks)
Closed system- have a heart & blood vessels (cephalopods)
Reproduction:


Hermaphrodite
External/Internal Fertilization
Phylum Echinodermata


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Echinoderm means: “spiny skinned”
Symmetry: Radial
Members: sea stars, sea cucumbers, sea urchins, sand
dollars
Phylum Echinodermata

Method of Feeding


Turn their stomachs inside out
Triangular feet (ampulla) around mouth scrap/
crush food
Phylum Echinodermata
 Skeleton
Endoskeleton- plates
called ossicles with
plates fused together
 Water vascular
system

Phylum Echinodermata

Characteristics:
 Systems:
 Nervous system (nerve ring with radial nerves in arms)
 Have Water Vascular System
 System of canals for water fluid (movement,
consuming, breathing)
 Reproduction:
 Hemaphrodite
 Ability to regenerate limbs
Sea Star Dissection!
Water Vascular System cont.

Madreporite



Is a opening used to
filter water into the WVS
Small red or yellow
button on the adoral
(near the mouth) surface
of the starfish
Ring Canal

A ring around the
esophogus with
connecting radial canals

Radial Canal


A branch off of the ring
canal that leads to an
arm (ray) and gives rise
to the tube feet
Tube feet

Water leaves ampulla
into the tube feet which
are small tubular
projections found most
on the oral face of the
sea star