Other Invertebrates

1
Other Invertebrates

• No external skeleton
• Are they arthropods?

2
Earthworms

• Swallow soil
• Decayed plant animal stuff is digested
• The rest just passes through (castings)
• Enriches soil
• Keeps soil loose so rain can soak in
• Breathes through skin
• 8 setae on each segment to move through soil
• Egg case

3
Parasitic Worms

• Leeches
• Fasten on skin and drink hosts blood
• Tapeworms
• Found in hosts intestines
• Take nutrients
• Roundworms
• Found in lymph nodes, intestines, muscles
• Take nutrients

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Mollusks

• New phylum!
• Mollusca
• Hard coverings called shells for protection
• Made of calcium carbonate (minerals from food)
• Starts as liquid in the mantle (tissue)
• Three types
• Univalveone shell
• Bivalvetwo shells
• Cephalopodhead-foot

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Snails Slugs

• Gastropods (stomach-foot)
• One muscular foot
• Looks like theyre sliding on their stomach
• Small gland coats foot with slime
• Without the slime, they couldnt move!

6

• Snails
• Eat young plants
• Foot contracts and expands to move
• In front of the footmouth, eyes, antennae
• Shell protects heart, stomach, other organs
• When in danger, pulls everything but the foot
  into the shell
• Other univalves
• Salt water snails
• Cowrie
• Conch

7

• Slugs
• Close relative of snail
• But no shell!
• Moves in the same way (gastropod)
• Sea slug or nudibranch
• Fringe of gills that look like feathers

8
Bivalves

• Two shells joined by hinges
• Mussels, oysters, clams, scallops
• When attacked, shell shuts tight!
• Some have a foot for movement
• Digs in sand
• Swells to make an anchor
• Pulls itself forward

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Cephalopods

• Foot head together
• All the vital organs are found there
• At base, two eyes and several tentacles
• Swim by jet propulsion!
• Suck air into body, then push it out

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Some Cephalopods

• Octopus
• 8 tentacles, each with 2 rows of muscles
• No shell
• Ink for defense
• Squid cuttlefish
• 10 tentacles with suction cups
• Internal shells to support protect head
• Ink or attack
• Nautilus
• External shell to protect inside when danger
• Up to 94 tentacles, but no suction cups

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Homework

• Comprehension Check
• Page 147
• Dont forget to give two examples!!