Most Mollusks have shells

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Most Mollusks have shells Echinoderms have
spiny skeleton

• MOLLUSKS ARE SOFT-BODIED ANIMALS
• MOLLUSKS SHOW A RANGE OF ADAPTATIONS
• ECHINODERMS HAVE UNUSUAL ADAPTATIONS

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Mollusks soft-bodied animals

• All mollusks have soft shell many have outer
  protective shell.
• All mollusks have a muscular foot (head is
  actually attached to its foot) and all mollusks
  have a mantle (layer of folded skin that protects
  its internal organs).
• Oyster, clams, snails, mussels are mollusks so
  are squid, octopus, slugs
• Live on land water environments
• Most have well-developed organ systems.
• Reproduce sexually

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Mollusks Bivalves

• Have hard shell of 2 matching halves (clam,
  mussel, oyster)
• Are filter feeders, filter food from surrounding
  water bivalve moves by pushing foot in out.
• Takes in oxygen by pair of gills (organ that
  filters dissolved oxygen from water) in most
  bivalves, gills also filter food.

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Gastropod Mollusks

• Gastropods protect selves by withdrawing into
  shells.
• Head is at end of its foot has eyes tentacles
  for sensing some have a radula(cutting mouth
  part to shred food)
• Some eat animals, most feed on plants algae
• Some have gills ( live in water) some have
  lungs ( live on land)

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Cephalopod Mollusks

• Live in saltwater (octopus, squid, chambered
  nautiluses). Well developed body systems.
• Brain nerves, eyes near mouth, tentacles for
  capturing prey..
• Mantle can push water forcefully thru a siphon to
  move animal.
• Gills take in oxygen, which goes into blood
  pumped (3 hearts)
• Most have no protective shells, but protective
  behavior (may change color, squirt ink, move
  quickly)
• Nautilus has shell, but made of separate chambers
  (inner filled with gas to help float-live in
  outer chamber)

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Mollusks range of adaptations

• Even though clam and octopus seem very different,
  still classified as mollusks.
• Foot of bivalve is simple muscle moving in out
  of shell to help move gastropods have head at
  end of foot muscles in foot let it glide over
  surfaces cephalopods have tentacles on foot to
  pull food into its mouth and to move along the
  ocean floor.

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Echinodermsstrange adaptations

• Invertebrates that live in ocean, have radial
  symmetry as adult (sea star, s.urchin,
  s.cucumber, sand dollars)
• Feed off ocean floor (mouth at center of body
  underneath) some filter food, others prey on
  clams,snails, other echinoderms.
• Means spiny-skinned (some have larger spines
  than others)
• Have skeletons of stiff plates just under their
  skin. Some are loosely connected for more
  movement (sea star), while others grow close
  together for less flexibility (sand dollar)

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Echinodermsstrange adaptations

• Echinoderms have a water vascular system of
  water-filled tubes, radiating out from center
  water comes in from openings on upper surface, to
  feed into tubes
• Muscles attach to top of tube to shut off water,
  causing suction at base of tube where feet are
  tube feet stick to ocean floor to move it around.
• Tube feet can also hunt prey, grab it and pull
  open shells. (sea star then pushes stomach out
  thru mouth into bivalves shell to digest its
  body)
• Not all echinoderms hunt, sea urchin eats algae
  on ocean floor.