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 Spiny
Skinned Animals
 Marine
 Slow moving or sessile
 Starfish, Sea Urchins, Sea
Cucumbers, Sand Dollars,
Feather Star
 Coelom
 One Way
Digestive Tract
 Radial Symmetry
 3 tissue layer
 Tube Feet
• Locomotion, feeding, and gas
exchange
Endoskeleton
•Internal Skeleton
 Nerve ring is centrally
located around the mouth
with radiating nerves
 Asexual
• Regeneration

Sexual Reproduction
• External Fertilization
Starfish
Five
arms that project
from a central disk
Bottom Dwellers
Carnivorous
No
Excretory System
Water Vascular System
 Water
is drawn in through
central disc
 Water passes through canals
 Water goes to bulb of tube
feet
 When
bulbs contract:
•Water is forced into tube
feet
•Creates a suction
 When
the bulbs relax:
•Water is pushed back
into canals
•Relaxes suction
 Marine
or land dwelling
 Have a soft body enclosed
by a shell or shells
• (Slugs have lost their mantle
and shells during evolution)
Bilateral
Symmetry
3 tissue layers
Coelom
Head is well developed
•Exception: clam
 Radula:
Feeding Device
• Rasping organ that scrapes
food in snails
 Muscular
Foot
 Gills for aquatic species
 One way digestive tract
 Visceral
Mass
Digestive, reproductive,
excretory, and circulatory
systems
 Mantel
( folded tissue )
• Forms shell
 Open
Circulatory System



Snails and slugs
Largest group of molluscs
Found in fresh water, salt water, and
terrestrial environments
 Eats plants, meat, or dead organisms
 Terrestrial
Gastropods
• Only mollucs that live on land
• No gills
• Simple lung
 Bivalves
• Valve = shell
 Oysters,
Clams, Mussels,
Scallops
 No Radula
 Gills used for respiration and
feeding
 Some are sessile (mussels)
 Squids
and Octopuses
 Most highly specialized mollusks
 Have a large brain
• Eyes are among the most complex
organs in animal kingdom
 Carnivorous
• Use beak like jaws and a radula to
crush or rip prey apart
 Foot
has evolved into
large arms that project
form the head
 Closed Circulatory
System