Transcript INVERTEBRATE ANIMALS

INVERTEBRATE ANIMALS
• MOST ANIMALS ARE INVERTEBRATES
• CNIDARIANS & WORMS HAVE DIFFERENT
BODY PLANS
• MOST MOLLUSKS HAVE SHELLS, &
ECHINODERMS HAVE SPINY SKELETONS
• ARTHROPODS HAVE EXOSKELETONS &
JOINTS
Most Animals are Invertebrates
• Invertebrates: animals with no backbone or
bone tissue. Some live in water, desserts and
even inside of other organisms.
• Most are small (crickets,oyster,sea star,
earthworm, spider). Giant squid though can be
about 60 feet long and weigh 1000lb.
SIX GROUPS OF INVERTEBRATES:
Sponges (simplest, live in water & filter food out of
water); Cnidarians (live in water, central
opening surrounded by tentacles); Worms (soft,
tube shaped body); Mollusks (muscular foot to
move or get food); Echinoderms (central
opening to take in food); Arthropods (found on
land, water & air, have legs, maybe wings)
SPONGES: Simplest Animals
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Sponges are simplest multicellular animals;
are sessile (live in 1 spot & don’t move);
have no tissue or organs just collection of cells;
feed constantly by filtering out plankton/small
organisms in water surrounding them.
• Sponge pore cells are on body wall leading into
larger canals with other cells. Specialized cells
filter out food particles & oxygen. Other cells
digest food. Some cells have spicules (spines
with calcium to make body hard & give support)
SPONGES
• Can reproduce asexually
by buds breaking off &
floating away, landing
& growing.
• Sexually release sperm
in water to either meet
eggs in other sponges,
or sometimes eggs
floating in water.
Fertilized egg forms
free swimming larva,
that will land, become
sessile again & grow
into adult sponge.