Download (jellies), Flatworms, Roundworms and Segmented Worms

3/15/2016
Invertebrates Part II
Invertebrates are animals without a
backbone.
Mollusks – Soft sea animals
• Soft bodied aquatic animals with a shell
• 4 Part body plan
– Foot- Muscular, used for movement
– Mantle- Tissue that makes shell
– Shell- Hard protective structure
– Viseral Mass- Internal organs
• Radula- feeding structure; can be specialized
• 3 Classes
– Gastropod- 1 shell
– Bivalve- 2 shell
– Cephalopods- foot divided into many
tentacles
(Still on Mollusks page)
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Body type- Bilateral Symmetry
Body Cavity- Coelom
Nervous System- developed; brain
Digestion- Extracellular, two opening tract
Circulatory- Closed system with a true
heart
• Respiratory- Gills or gill-like structures
• Reproduction- Sexual, very little asexual
• Skeleton- Exoskeleton; hydrostatic
Examples – Snail (top left), slug,
scallop (bottom left), clam, oyster,
octopus (right), squid
Annelida – Segmented Worms
• Bodies are soft but more complex than
other worms
• Segmented body, most with 1 nerve and 1
blood vessel
• Well developed sense organs and internal
organs compared to first few groups we
studied
• Most are aquatic
• First group with a true body cavity
(coelom)
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(Still on Segmented Worms page)
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Body type- Bilateral Symmetry
Body Cavity- Coelom
Nervous System- Moderately developed; brain
Digestion- Extracellular, two opening tract
Circulatory- Small heart-like structures
Closed System
• Respiratory- Gas exchange by diffusion
• Reproduction- Asexual or Sexual;
hermaphrodites who pair up and fertilize each
other
• Skeleton- Hydrostatic
Examples–Earthworms, leeches (right),
spaghetti worm, pompeii worm (left)
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Arthropods – Jointed appendages
Have jointed legs and chitin exoskeletons
Segmented bodies
Molt as they grow
4 Classes alive today
– Chelicerata (arachnids, horseshoe crabs)- 8
legs 2 segments
– Myriapoda- Many segments; either 1 leg pair
(centipedes) or 2 (millipedes) per segment
– Hexapods- Insects; 6 legs, 3 segments
– Crustaceans- 2 pairs of antennae; hard
exoskeleton
(Still on Arthopod page)
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Body type- Bilateral Symmetry
Body Cavity- Coelom
Nervous System- developed; brain
Digestion- Extracellular, two opening tract
Circulatory- Open system with a true heart
Respiratory- Simple lungs or air tubes
Reproduction- Sexual, very little asexual
Skeleton- Exoskeleton (hard shell of
chitin)
Examples – Ants (left) and other
insects, lobster (center), shrimp, crabs,
millipedes (right), spiders, scorpions
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Echinoderms – Spiny skin
• Advanced embryo development, similar to
vertebrates
• Have 5 or more arms
• Found in marine biomes
• Eats by pushing stomach out of the mouth
• 5 Classes: Starfish, Brittle stars, Sea
urchins and Sand dollars, Sea Cucumber,
Sea Lillies and Feather stars
• Amazing powers of regeneration
(Still on Echinoderm page)
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Body type- Radial Symmetry
Body Cavity- Coelom
Nervous System- Simple; no brain
Digestion- Extracellular, two opening tract
Circulatory- Unique water vascular system
Respiratory- Gills or gill-like structures
Reproduction- Sexual, asexual when
regenerating
• Skeleton- Endoskeleton
Examples – Starfish (top left),
Brittle star (right), Sea urchins
(bottoms left), Sea cucumbers
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