Transcript Major Divisions of Life - FSU Biology

How does Cnidaria fit in?
Cnidaria
3 classes:Hydrozoa, Scyphozoa, Anthozoa
Porifera
2 body types: polyp, medusa
diploblastic
3 body types
tissue level
choanocytes
of organization
cellular level
of organization
Blastula stage
heterotrophic
multicellular
eukaryote
unknown
common ancestor
How do the Acoelomates fit
in?
the acoelomates
Platyhelminthes
Porifera
Cnidaria
unknown
common ancestor
Nemertea
The Acoelomates
Acoelomate Characteristics
Organ level of organization
Tissues are organized to for
organs which are used to
accomplish physiological
functions
Acoelomate Characteristics
Triploblastic
3 Embryonic Germ Layers
3 Tissue Layers
endoderm
gastrodermis
mesoderm
mesoderm
ectoderm
epidermis
Acoelomate Characteristics
No body cavity
ectoderm
ectoderm
mesoderm
mesoderm
Gut
endoderm
endoderm
Acoelomate Characteristics
Mesoderm
(mesenchyme,
parenchyma)
Triploblastic
Gut
Ectoderm
Endoderm
Acoelomate Characteristics
Bilateral Symmetry
Anterior: toward the front of the
body
Posterior: toward the rear of the
body
Acoelomate Characteristics
Cephalization
the concentration of sensory
organs in the head of the
animal
Eye spots
Auricles
Phylum Platyhelminthes
the flatworms
Physiology
Feeding
– Free-living, carnivorous
– parasitic
Digestion
– intestine is simple or branched
– incomplete system (no anus)
– digestive system reduced or absent
in parasitic species
Physiology
Osmoregulation and excretion
– Protonephridia and flame cells
– much excretion is via diffusion
protonephridia
flame cell
Physiology
Nervous system
-ladder-like
-cephalization
-nervous system is
reduced in parasitic
species
Skeletal and circulatory
systems
– absent
Cerebral ganglia
Lateral nerve
cords
Physiology
Reproduction
Asexual
Sexual
– usually monoecious, but most must cross
fertilize
– Internal fertilization (usually reciprocal)
Phylum Platyhelminthes
Class Turbellaria
Class Trematoda
Class Cestoda
Class Turbellaria
Free-living flatworms
• move on slime trails
using cilia
Class Turbellaria
• predatory
• use a pharynx to capture
prey
pharynx
Class Turbellaria
• have a branched (or lobed) gut
ClassTurbellaria
Reproduction
Asexual
– Fission
ClassTurbellaria
Reproduction
Sexual
– internal fertilization
– simple life cycle
Adaptations for Parasitism
• increased reproductive potential
• monoecious
• presence of adhesion organs (suckers, hooks)
• poorly developed sensory systems
• reduced, or absent, digestive system
• resistant cuticle
• complex life cycles with more than 1 host
Class Trematoda
Parasitic Flukes
• endoparasitic
Trematoda Life Cycle
• have at least two hosts in their life cycle
• final host = vertebrate
Vertebrate
host #1
infective stage
in host muscle
Vertebrate
host #2
Invertebrate
host eats eggs
adult fluke
(in host liver)
Class Cestoda
Parasitic tapeworms
Class Cestoda
2 body regions: scolex and proglottids
scolex
proglottids
Class Cestoda
Scolex
suckers
rostellum
Class Cestoda
Proglottids
• repeating segments containing
reproductive organs
• may be immature, mature, or
gravid
Class Cestoda
Immature proglottids
• found at the anterior
end of the tapeworm
• contain no noticeable
sex organs
Class Cestoda
Mature proglottids
• found in the middle of
the tapeworm
• contain noticeable
sex organs
• sperm must come
from either a different
proglottid or a different
individual
Class Cestoda
Mature proglottids
genital pore
sperm duct
vagina
uterus
ovary
testes
Class Cestoda
Gravid proglottids
• found at the posterior
end of the tapeworm
• contain fertilized eggs
• entire proglottid is
shed in the host’s feces
uterus
eggs
Cestoda Life Cycle
Adult tapeworm
(in host intestine)
Gravid
proglottids
Vertebrate
host #2
Infective
stage in host
muscle
eggs
Vertebrate host #1
Ecology
•Parasitic flatworms infect many people in some
parts of the world (for example, the Chinese liver
fluke infects approx. 30 million people in Asia)
•Some Trematodes have display polyembyony: a
single larvae can have up to 4 younger larvae
developing within it
•Trematodes are a model system for studying host
parasite coevolution
Phylum Nemertea
the ribbonworms
Physiology
Feeding
– Free-living, carnivorous
– have an eversible proboscis that is
not connected to the digestive
system
– Proboscis is used to stab prey and
may have a poisonous tip (or stylet)
Physiology
rhynchocoel
proboscis
mouth
rhynchocoel
Physiology
Digestion
– intestine is unbranched
– complete system (mouth and anus)
This is the first animal to have an anus!!!
Physiology
Reproduction
Asexual
– Some species are capable of reproducing
asexually through fragmentation and
regeneration
Sexual
– usually dioecious
– internal fertilization
Physiology
Osmoregulation and excretion
– same as Platyhelminthes
Nervous system
– same as Platyhelminthes
Skeletal system
same as Platyhelminthes
Physiology
Circulation
– closed circulatory system
consisting of contractile blood
vessels
This is the first animal to have a closed circulatory system!!!
Ecology
•Nemerteans are mostly marine, although there
are a few species found in freshwater (and even a
few on land!)
•They range in size from a few millimeters to 30
meters
•Their biology is little known in part because they
are extremely fragile and fragment easily
How do the acoelomates fit in?
Nemertea
Platyhelminthes
acoelomate
Complete digestive system
acoelomate
Cnidaria
Porifera
Closed circ. system
Ladder-like
nervous
system
proboscis
cephalization
protonephridia
organ level of organization
triploblastic
unknown
common ancestor