Download simple animals

SIMPLE ANIMALS
All Animals
• Heterotrophs that ingest their food
• Multicellar formed from eukaryotic cells that lack
plastids and cell walls
• Move using contractile fibers
• Most reproduce sexually by gametes produced by
gonads: ovaries and testes
Symmetry
• Animals can be categorized according to the symmetry of
their bodies, or lack of it
– None
– Bilateral
– Radial
• Two-sided symmetry is called bilateral symmetry
• Bilaterally symmetrical animals have:
– A dorsal (top) side and a ventral (bottom) side
– A right and left side
– Anterior (head) and posterior (tail) ends
– Cephalization, the development of a head
Fig. 32-7
(a) Radial symmetry
(b) Bilateral symmetry
Level of organization
• Tissue
• Organs
• Organ systems
Embryonic Tissues
• Animal body plans also vary according to the
organization of the animal’s tissues
• Tissues are collections of specialized cells isolated
from other tissues by membranous layers
• During development, three germ layers give rise to
the tissues and organs of the animal embryo
• Ectoderm is the germ layer covering the embryo’s
surface
• Endoderm is the innermost germ layer and lines
the developing digestive tube
• Diploblastic animals have ectoderm and endoderm
• Triploblastic animals also have an intervening
mesoderm layer; these include all bilaterians
Body Plan
• None
• Sac-like: one main opening
• Tube-within-a-tube: mouth at one and end
anus at the other
Body Cavities
• Most triploblastic animals possess a body cavity
• A true body cavity is called a coelom and is derived
from mesoderm
• Coelomates are animals that possess a true coelom
Fig. 32-8
Coelom
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
(a) Coelomate
Body covering
(from ectoderm)
Pseudocoelom
Muscle layer
(from
mesoderm)
Digestive tract
(from endoderm)
(b) Pseudocoelomate
Body covering
(from ectoderm)
Tissuefilled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)
(c) Acoelomate
Fig. 32-8a
Coelom
Body covering
(from ectoderm)
Digestive tract
(from endoderm)
(a) Coelomate
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
• A pseudocoelom is a body cavity derived from the
mesoderm and endoderm
• Triploblastic animals that possess a pseudocoelom
are called pseudocoelomates
Fig. 32-8b
Body covering
(from ectoderm)
Pseudocoelom
Digestive tract
(from endoderm)
(b) Pseudocoelomate
Muscle layer
(from
mesoderm)
• Triploblastic animals that lack a body cavity are
called acoelomates
Fig. 32-8c
Body covering
(from ectoderm)
Tissuefilled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)
(c) Acoelomate
Fate of the Blastopore
• The blastopore forms during gastrulation and
connects the archenteron to the exterior of the
gastrula
• In protostome development, the blastopore
becomes the mouth
• In deuterostome development, the blastopore
becomes the anus
Fig. 32-9c
Protostome development
(examples: molluscs,
annelids)
Deuterostome development
(examples: echinoderms,
chordates)
Anus
Mouth
(c) Fate of the blastopore
Key
Digestive tube
Anus
Mouth
Mouth develops from blastopore. Anus develops from blastopore.
Ectoderm
Mesoderm
Endoderm
Sponges: Porifera
• Sponges are sedentary animals
• They live in both fresh and marine waters
• Sponges lack true tissues and organs
• Sponges are suspension feeders, capturing food
particles suspended in the water that pass through
their body
• Choanocytes, flagellated collar cells, generate a water
current through the sponge and ingest suspended
food
• Water is drawn through pores into a cavity called the
spongocoel, and out through an opening called the
osculum
• Classified by type of Spicule which is the skeltal
element they possess
– Chalk sponges-calcium carbonate
– Glass sponges-siliceous
– Fibrous sponges-protienaceous
Fig. 33-4
Food particles
in mucus
Flagellum
Choanocyte
Collar
Choanocyte
Osculum
Azure vase sponge (Callyspongia
plicifera)
Spongocoel
Phagocytosis of
food particles
Pore
Epidermis
Spicules
Water
flow
Amoebocytes
Mesohyl
Amoebocyte
• Sponges consist of a noncellular mesohyl layer
between two cell layers
• Amoebocytes are found in the mesohyl and play
roles in digestion and structure
• Most sponges are hermaphrodites: Each individual
functions as both male and female
• Some sponges produce asexual reproductive
bodies called gemmules that are release into the
water.
Jellyfish, coral, anemonesPhylum Cnidaria
• Cnidarians have diversified into a wide range of
both sessile and motile forms including jellies,
corals, and hydras
• They exhibit a relatively simple diploblastic, radial
body plan
• The basic body plan of a cnidarian is a sac with a
central digestive compartment, the gastrovascular
cavity
• A single opening functions as mouth and anus
• There are two variations on the body plan: the
sessile polyp and motile medusa
Fig. 33-5
Mouth/anus
Polyp
Tentacle
Medusa
Gastrovascular
cavity
Endoderm
Body
stalk
Mesoglea
Ectoderm
Tentacle
Mouth/anus
• Cnidarians are carnivores that use tentacles to
capture prey
• The tentacles are armed with cnidocytes, unique
cells that function in defense and capture of prey
• Nematocysts are specialized organelles within
cnidocytes that eject a stinging thread
Fig. 33-6
Tentacle
Cuticle
of prey
Thread
Nematocyst
“Trigger”
Thread
discharges
Cnidocyte
Thread
(coiled)
Fig. 33-7
(b) Jellies (class
Scyphozoa)
(a) Colonial polyps (class
Hydrozoa)
(c) Sea wasp (class
Cubozoa)
(d) Sea anemone (class
Anthozoa)
Hydrozoans
• Most hydrozoans alternate between polyp and
medusa forms
Fig. 33-8-3
Feeding
polyp
Reproductive
polyp
Medusa
bud
ASEXUAL
REPRODUCTION
(BUDDING)
Portion of
a colony
of polyps
Haploid (n)
Diploid (2n)
Gonad
Medusa
Egg
SEXUAL
REPRODUCTION
Sperm
FERTILIZATION
Zygote
1 mm
Key
MEIOSIS
Developing
polyp
Mature
polyp
Planula
(larva)
Flatworms- Phylum Platyhelminthes
• Members of phylum Platyhelminthes live in marine,
freshwater, and damp terrestrial habitats
• Although flatworms undergo triploblastic
development, they are acoelomates
• They are flattened dorsoventrally and have a
gastrovascular cavity
• They can be parasites
Turbellarians
• Turbellarians are nearly all free-living and mostly
marine
• The best-known turbellarians are commonly called
planarians
• Planarians have light-sensitive eyespots and
centralized nerve nets
• The planarian nervous system is more complex and
centralized than the nerve nets of cnidarians
• Planarians are hermaphrodites and can reproduce
sexually, or asexually through fission
Fig. 33-10
Pharynx
Gastrovascular
cavity
Mouth
Eyespots
Ganglia
Ventral nerve cords
Tapeworms
• Tapeworms are parasites of vertebrates and lack a
digestive system
• Tapeworms absorb nutrients from the host’s
intestine
• Fertilized eggs, produced by sexual reproduction,
leave the host’s body in feces
• http://www.youtube.com/watch?v=T6pAfQInf2c
Know This
Nematodes
• Nematodes, or roundworms, are found in most aquatic
habitats, in the soil, in moist tissues of plants, and in
body fluids and tissues of animals
• They have an alimentary canal, but lack a circulatory
system
• Reproduction in nematodes is usually sexual, by
internal fertilization
• Pseudocoelmate
• Some parasitic
• http://www.capcvet.org/capcrecommendations/ascarid-roundworm
Know This
Trichinella
Ascaris
Assignments
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Assignment 1-all
Assignment 2-all
Assignment 3-exclude j
Assignment 4
Exclude 5
Make a chart of all key traits describe in lab
book for the phyla discussed