Invertebrates

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Invertebrates
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Definition

• Sub-Kingdom of Animals
• Animals that do not have a backbone at anytime
  during their development
• There are 8 major phyla of invertebrates

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PoriferaSponges Pore Bearer

• Characteristics
• Two cell layers with one body opening
• Most are asymmetrical
• Sessile (Do not move-Stuck in one place)
• Filter Feeders

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Cnidarians

• Characteristics
• Two cell layers with one body opening
• Most radial symmetry
• Have stinging cells (nematocysts)
• Two life stages, polyp (baby) and medusa
  (adult)
• Examples
• Jellyfish, corals, sea anemones, hydras

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PlatyhelminthesFlatworms

• Characteristics
• Bilateral symmetry
• Flattened bodies
• One body opening
• Slightly developed nervous and sensory systems
• Examples
• Tapeworms, flukes, planarians

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Tapeworms in Body
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NematodaRoundworms

• Characteristics
• Tubelike digestive system with 2 body openings
• Many parasitichurt other organisms
• Sensory eyespots

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HeartwormA Parasitic Roundworm
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MolluscaMollusks

• Characteristics
• Bilateral symmetry
• Body cavity for organs
• 2 Body openings with completed digestive tract
• Mantle (surrounds internal organs secretes
  shell in most mollusks)
• Muscular foot for movement

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Mollusca Continued

• Live in water
• Examples
• Gastropods (1 Shell)
• Snails
• Bivalves (2 Shells)
• Clams
• Cephalopods (head-footed)
• Octopi, Squid

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AnnelidaSegmented Worms

• Characterisitcs
• Bilateral Symmetry
• Coelom and two body openings
• Segmentationprovides for great flexibility
• Examples
• Leeches, earthworms, bristleworms

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Arthropods

• Characteristics
• Bilateral Symmetry
• Exoskeletonstough outer coverings that
  protects and provides support
• Jointed appendages
• Some have fused segments
• Examples
• Insects, spiders, crabs, centipedes

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Echinodermata

• Characteristics
• Radial Symmetry
• (Larvae have radial)
• Endoskeletoninternal skeleton for support
• Rough exterior that looks like a spiny skin
• Water vascular system for movementchanges
  pressure which creates a suction on feet
• Examples
• Sea Stars, Starfish, Sand Dollars

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Invertebrate Chordate

• Characteristics
• ChordatesHave a notochord, dorsal nerve cord,
  gill slits, muscle blocks during all or part of
  life cycle
• Bilateral Symmetry
• Most advanced of invertebrates
• Examples
• Tunicates (Sea squirts), lancets