Transcript Intro Invertebrates

Intro to the Invertebrates
What is an Animal?
Basic Definitions
• What is an animal?
– a multicellular eukaryotic heterotroph
whose cells lack cell walls.
• What is an invertebrate?
– an animal that does not have a backbone.
What is an Invertebrate?
Simple to more complex
The Phlya of Invertebrates
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Porifera
Cnidaria
Platyhelminthes
Nematoda
Annelida
Arthropoda
Echinodermata
Phylum
Porifera
Cnidaria
Examples
sponges
jellyfish, hydra, coral
Evolutionary
Milestone
multicellularity
tissues
Platyhelmint
flatworms
hes
bilateral symmetry
Nematoda
Mollusca
Annelida
roundworms
clams, squids, snails
earthworms, leeches
pseudocoelom
coelom
segmentation
Arthropoda
insects, spiders,
crustaceans
jointed appendages
Echinoderm
starfish
ata
deuterostomes
Chordata
notochord
vertebrates
Vocabulary
• Radial Symmetry: having body parts
that repeat about an imaginary line
through the center of the body.
• Bilateral Symmetry: having body parts
that repeat on either side of the body.
• Cephalization (cephalo = head): the
gathering of sense organs and nerve
cells into the head region.
• Ganglia- Clusters of nerve tissue
• Hermaphrodite: having both sexes in one animal.
Symmetry
Embryonic Development:
Zygote = fertilized egg
Blastula = a hollow ball of cells
Blastopore = the blastula folds in
creating an opening
Protostome = mouth is formed from
blastopore
Deuterosome = anus is formed from
blastopore
Different Body Plans
• Coelom: body cavity that is completely
lined with mesoderm.
• A coelomate is an animal with a coelom.
• An acoelomate is an animal without a
coelom.
Body Plans
Phylum Porifera
Sponges
Sponges (Phylum Porifera)
• Sponges have no specialized
tissues.
• Many holes called pores, or
ostia.
• Osculum – large opening at the
top. Water is taken into the
sponge through its many pores
and circulated out through the •
osculum. This is how they
‘breathe’
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• They have no muscle or
nervous system.
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Sponges are sesslie –
which means they do not
move.
Sponges filter food out of
the water as it flows
through the ostia. Special
cells called collar cells pick
up the food and start
digestion.
Sponges can regenerate
lost body parts.
Sponge Anatomy
Phylum Cnidaria
Jellyfish, Coral, Hydra, Sea
Anemone, Portuguese-man-of-war
Cnidaria
• “Stinging Cell” animals with raadial
symmetry.
• They have Nematocysts – stinging cells in
the tentacles, activated by touch.
Provides protection and helps capture
food.
• Some are sessile, some can ‘swim’.
• They are hermaphrodites (contain both
male and female reproductive structures
in the same body.
• They have 3 layers
– Ectoderm – outer cell layer
– Endoderm – inner cell layer
– Mesoglea – jelly-like layer separating ectoderm and
endoderm. Within the mesoglea is a nerve net. There is
no brain.
• They contain a central cavity called the gastrovascular
cavity, or enteron. Digestion takes place here and the
contents are absorbed by the endodermal cells. The
undigested food is expelled through the mouth.
2 Body forms in Cnidaria
Polyp Form
Medusa Form
Phylum Platyhelminthes
Planarians, Flukes, and Tapeworms
Platyhelminthes or Flatworms (the
simplest bilateral animals)
• Three classes
• Planarians are mostly free-living, non-parasitic,
and marine
• Flukes are parasites
• Tapeworms are parasites (with hooks and suckers
that anchor the worm inside the intestines of a host
animal)
Anatomy of a Flatworm
Ever see the ALIEN movies?
Phylum Nematoda
Roundworms and Rotifers
Nematodes
• Roundworms can be
parasitic (hookworm,
pinworm, threadworm) or
non-parasitic, they can
also be decomposers.
They have pointed heads
and tapered tails with a
complete digestive tract.
• Rotifers are tiny animals,
with a crown of cilia and a
complete digestive tract.
They are common in
freshwater.
Nematode Anatomy
Phylum
Annelida
Earthworms,
Leeches and
Polychaetes
Christmas Tree Worm
Annelids
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Segmented bodies; Bilateral symmetry
True body cavity (coelom). The organs of the
digestive, nervous, and circulatory systems run
the length of the body.
Complex digestive and circulatory systems.
Earthworms are hermaphrodites.
Small brain located near the pharynx. A ventral
nerve cord extends from the brain and runs the
length of the body. In each segment it swells to
form structures called ganglia.
Their muscular system contains both circular
and longitudinal muscles. As these muscles
contract and relax they shorten and elongate
the body making it move. Setae, small bristlelike hairs, extend from the body walls and act
as anchors as the worm moves.
They have a hydrostatic skeleton (water-filled
tube).
No respiratory organs; worms breathe through
their moist skin.
Earthworm Anatomy
Phylum Mollusca
Can you see the Giant Clam in this photo?
Clams, Squid, Octopus
Mollusks
• Mollusks have bilateral symmetry.
• Their body is covered with a thin membrane called the
mantle. This structure may secrete the shell.
• Three body parts: head, muscular foot, and the visceral
hump (contains the internal organs).
• Breathing occurs through the gills or the lining of the
mantle cavity.
• Squid and octopus are the most intelligent
invertebrates. They are about as smart as a house cat.
• Reproduction is sexual.
• They are true coelomates.
Check out the complex anatomy of a clam
Giant squid- an amazing mollusk
Giant squid
• Head: houses a complex brain.
Eyes: largest in the animal kingdom. They can grow to
25 cm (10 in.) in diameter--about the size of a volleyball.
Fins: relatively small in this species. They help balance
and maneuver the huge animal as it swims.
Mantle: the main body. This muscular sac contains most
of the organ systems.
Arms (8): studded with two rows of suckers.
Feeding tentacles (2)
• Funnel: a multipurpose tube used in breathing, jetting,
squirting ink, laying eggs, and expelling waste.