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How does Cnidaria fit in? - PowerPoint PPT Presentation
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How does Cnidaria fit in?. Cnidaria. 3 classes:Hydrozoa, Scyphozoa, Anthozoa . Porifera. 2 body types: polyp, medusa. diploblastic. 3 body types . tissue level of organization. choanocytes. cellular level of organization. Blastula stage. heterotrophic. multicellular. unknown
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How does Cnidaria fit in?
Cnidaria
3 classes:Hydrozoa, Scyphozoa, Anthozoa
Porifera
2 body types: polyp, medusa
diploblastic
3 body types
tissue level
of organization
choanocytes
cellular level
of organization
Blastula stage
heterotrophic
multicellular
unknown
common ancestor
eukaryote
How do the Acoelomates fit in?
the acoelomates
Platyhelminthes
Nemertea
Cnidaria
Porifera
unknown
common ancestor
Acoelomate Characteristics
Organ level of organization
Tissues are organized to for organs which are used to accomplish physiological functions
Acoelomate Characteristics
Triploblastic
3 Tissue Layers
gastrodermis
mesoderm
epidermis
3 Embryonic Germ Layers
endoderm
mesoderm
ectoderm
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
Cerebral ganglia
Nervous system
-ladder-like
-cephalization
-nervous system is
reduced in parasitic
species
Lateral nerve cords
Skeletal and circulatory systems
- absent
Physiology
Reproduction
Asexual
Sexual
- usually monoecious, but most must cross fertilize
- Internal fertilization (usually reciprocal)
Class Turbellaria
- Free-living flatworms
- move on slime trails using cilia
Class Turbellaria
- have a branched (or lobed) gut
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
adult fluke
(in host liver)
Invertebrate
host eats eggs
Class Cestoda
Parasitic tapeworms
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
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
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
Closed circ. system
Ladder-like nervous system
Cnidaria
proboscis
Porifera
cephalization
protonephridia
organ level of organization
triploblastic
unknown
common ancestor
