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INVERTEBRATE DIVERSITY
Animal diversity is very intense!
Blue-ringed
octopus – one of
the deadliest
animals in the
ocean.
Lives in shallow
reefs and tide
pools from Japan
to Australia.
• Octopi are incredibly intelligent.
• They are masters of disguise, using
camouflage as a defense mechanism.
• The blue-ringed octopus injects
poison into its prey or into the
vicinity of its prey.
• It also uses a different substance for
self-defense that is 10,000 times
more lethal than cyanide.
MIMIC OCTOPUS
Can look like a
venomous sea snake, a
toxic flatfish, a sea
anemone, or a jellyfish!
Only a mimic octopus
can mimic multiple toxic
animals.
Characteristics of Animals
• Eukaryotic
• Multicellular (eliminates the protists)
• Moveable (at least one time in it’s life
cycle)
• Heterotrophs that ingest their
food within their bodies after
ingesting organisms, dead or
alive, whole or by the piece.
The animal way of life
• Animal cells lack cell walls that provide
support to plants and fungi.
• Animals are held together by
extracellular proteins.
• Most have muscle cells for movement
and nerve cells for conducting impulses.
• Most animals are diploid and reproduce
sexually.
• Egg and sperm are the only haploid cells.
• (Ants, bees, and wasps have some males
that develop from unfertilized eggs that
are haploid)
• Sperm and egg join to form a zygote.
• The zygote develops into a multicellular
adult.
• The zygote divides repeatedly in half until
there is a ball of cells called a blastula.
• One side of the ball of cells folds inwards
forming a gastrula.
• If the gastrula becomes an anus, the
animal is a deuterostome
(echinoderms and chordates). A
mouth develops from a second
opening later.
•
If the gastrula becomes a mouth, the
animal is a protostome.
Larva
• After gastrulation, many animals develop
directly into adults.
• Others develop into one or more larva
stages first.
• Larva undergo metamorphosis (major
body change) in developing into an
sexually reproducing adult.
• Animals have been
around for roughly a
billion years.
• The fossil record
shows a giant
explosion of animal
diversity in the
Cambrian era
(approx. 542 million
years ago).
THERE IS NO “ONE” BEST ANIMAL
Each form, each adaptation, and
each body plan has advantages and
disadvantages.
Phylogeny
• The evolutionary
history of animals
(where they come
from).
• The phylums are on
the far right.
• The branch points
indicate a common
ancestor between
the two branches.
• Animal body plans vary in
symmetry, body cavity, and
number of germ layers.
• First branch: true
tissues or no true
tissues.
• If there are no true
tissues, then the
animal is a sponge.
• If there are true
tissues, then the
animal is a
eumetazoan.
Next Division – Body Symmetry
Radial Symmetry
Bilateral Symmetry
Radial Symmetry
• Example: Sea
Anemone
• No matter where
you cut through it ,
it will be the same
on either side.
• Exampe:
Cnidarians.
Radial Symmetry
• The animal has a top and a bottom
but lacks front and back or right and
left sides.
• Radial animals are sedentary or
passive drifting.
Bilateral Symmetry
• If you cut the
organism down
the middle,
there is a
definite right
side and a
definite left side.
Bilateral Symmetry
• These animals have mirror-image right
and left sides, a distinct head and tail,
and a back (dorsal) and belly (ventral)
surface.
• They also have a brain, sense organs and
mouth located in the head.
• Facilitates mobility; the animals meets its
environment head-first.
What does the gastrula become?
• If the gastrula
becomes an anus,
the animal is a
deuterostome.
• If the gastrula
becomes a mouth,
the animal is a
protostome.
Tissues
• Outer Layer –
Ectoderm
• These are the outer
coverings that
become your skin
or in some
organisms becomes
nerves and the
brain
Endoderm
• The endoderm is
in the middle and
becomes the
linings of the
organs.
Mesoderm
• The mesoderm becomes the muscle and bones.
Animals body plans vary in
organization of tissues.
Phylum Porifera
means “pores”
flagella on the
Inside driving he
water through
which is
full of
particulates.
water moves
through the pores
Purple
Tube
Sponge
Porifera - Sponges
• Sponges lack true tissues.
• In other animals, cell layers formed during
gastrulation give rise to tissues and organs.
• Some animals have only ectoderm and
endoderm, but most animals also have
mesoderm.
Glass Sponge – Venus Flowering Basket
Silica Spicules
Cnidarians
Cnidarians – True Animals
• Sea anemones
• Jelly fish
• Sea anemone – tentacles up and are fixed on
the bottom
• “hydra” stage
• Tentacles containing “stinging cells.”
• In the jellies, the
tentacles are facing
downward.
• They have a mouth
that also serves as an
anus.
• Also have stinging
cells.
• Called the “medusa
stage.”
Body cavities of animals vary.
Flatworms
• Example: Planaria
• Have simple eyespots.
• Mouth is located on
their stomach.
• Can cut their head in
half and it will
generate two heads.
Tapeworms
• Tapeworm parasites are found in beef and
pork and other animals.
• Tapeworm infections in humans are caused
by eating raw or undercooked infected meat.
• The tapeworm larva develops in the human
intestine and can grow up to 12 feet.
Tapeworms
Tapeworm (cont’d)
• Scolex on the anterior end to attach to their host.
• They do not have a “true” digestive system.
• They absorb nutrients through their flat-bodied
skin.
• THEY CAN BE DOZENS OF FEET LONG.
Nematode Worms
• Longitudinal muscles
• Over 500,000
species, many are
parasitic.
• They have a true
digestive system.
• Example:
Heartworms in dogs.
Nematodes parasitic on Humans
• Ascarids (roundworms)
• Hookworms
• Pinworms
Heartworms in a Dog
Molluscs
• All have a
muscular foot.
• All have a visceral
mass containing
most of the
internal organs.
• Their mantle may
secrete a shell to
enclose the
visceral mass.
• Gastropods – largest groups of
mollusks and include snails and slugs.
• Most snails are protected by a single, spiral
shell.
• In land snails, the lining of the mantle cavity
functions as a lung.
• Slugs have lost their mantel and shell and
have long colorful projections that function as
gills.
Sea Slug
Bivalves
• Shells divided into
halves that are
hinged together.
• Examples: clams,
oysters, mussels, and
scallops
• Most are sedentary
suspension feeders.
Cephalopods
• Octopi, squid, cuttlefish.
• Means “head-feet”
• They are found in all oceans and cannot live in
fresh water.
• Agile predators!
• Large brains
• Beak-like jaws
Annelids – Segmented Worms
• Repeated parts – segments
• Example: earthworms and leeches
• They have an closed circulatory system.
Squid
Medicinal Leech
Arthropods
• Over a million species.
• Crayfish, lobsters, crabs,
spiders, ticks, and
insects.
• Success is due to
segmentation, a hard
skeleton, and jointed
appendages
Structure of an Arthropod
Insects
Most successful of all animals!
• More than a million species of insects have
been identified.
• Many can fly.
• Waterproof coating on the cuticle.
Protective Color Patterns
Mimicry