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Marine Worms

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Marine Worms
Bilateral Symmetry
6 New Things That Add Complexity
1. Mesoderm
2. Central Nervous System
3. Excretory System
4. Complete Digestive System
5. Coelom
6. Circulatory System
2 Worm Phyla
• There are two phyla that have “worms”
• Platyhelminthes
Phylum
Translation
Major Feature
Platyhelminthes
Broad, flat, worm
A flat body
They can move!
• Mesoderm
– An extra
layer of
cells
– Gives rise
to muscles
Digestive System
• Only one
opening
• Pharynx
extends
from body
• Undigested
food leaves
mouth
Central Nervous System
• Brain at anterior
• Nerve cord extended to
posterior
• Sensory cells respond to
light (eyes)
• Auricles are flaps on
head
• Two nerve cords are
connected, so we call it
ladder-like
Excretory System
• Network of tubes that opens through pores in
posterior
• Beating flagella that create water currents
• Removes waste
• Flame Bulbs
No circulatory system
• Get oxygen from body cells easily
• Like Porifera and Cnidaria
Feature
Platyhelminthes
Body Symmetry
Bilateral
Body segmentation
None
Type of skeleton
Hydrostatic
Type of digestive tract
Sac-like
Type of nervous system
Ladderlike
Method of respiration
Skin
Unique feature
Flame Cells
Economic Importance
Some Parasites Damage Livestock
Environmental niche
More Complex Worms
• Annelida
Phylum
Translation
Major Feature
Annelida
Has rings
Body has ringlike
segments
Polychaetes
• Most marine
worms belong to
this class
• They often have
muscular flaps
on their sides
called parapodia
• The parapodia
have bristles
called setae
• Proboscis
Tubeworms
• Sessile
polychaetes
• Excrete tubes
that they live in
• Attached to rocks
• Use feathery
tentacles
to catch food
Digestion
• Mouth, Tube, Anus
• Many new advantages
– Can eat while digesting
– Specialized parts
Mesoderm
• 2 types of muscle
– Circular
– Longitudinal
• While movement occurs, setae hold worm in
place
Nervous System
• Nerve clusters in anterior (brain)
Excretory System
• Each segment has a nephridia
• Filters fluid
Feature
Annelida
Circulatory
System
Body Symmetry
Bilateral
Body segmentation
• Closed
Segmented
of skeleton
Hydrostatic
– HasType
vessels
pumping blood
– Blood
delivers
of body
Type of digestive
tractnutrients to all partsComplete
– Animal
is able
to become bigger Ventral
Type of nervous
system
Method of respiration
Skin
Unique feature
Parapodia; organs repeated in segments
Economic Importance
Fish bait; food for tropical fish
Environmental niche
Food for other reef animals
Phylum Mollusca
Phylum
Translation
Major Feature
Mollusca
A soft shellfish
Soft body; many have shells
3 main characteristics
• Foot
• Mantle
• Radula
Class Gastropoda
•
•
•
•
•
Gastro- stomach
Poda- foot
Stomach Foot
Snails
Some have shells, some don’t
Class Bivalvia
• Clams, Mussels, Oysters, Scallops
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