Invertebrates

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Invertebrates

• Packet 77
• Chapters 33 47

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Introduction I
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Introduction II
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Invertebrates- Animals Without Backbones

• Ninety five percent of all known animals species
  are invertebrates.
• Invertebrates have a worldwide distribution
  ranging from deep sea hydrothermal vents to the
  polar deserts of Antartica.

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Invertebrates II

• Invertebrates can be separated into multiple
  categories
• Aceolomates
• The Sponges
• The Cnidarians
• The Flatworm
• Protostomes (Blastopore Mouth)
• The Roundworms
• The Segmented Worms
• The Mollusks
• The Arthropods
• Deuterostomes (Blastopore Anus)
• The Echinoderms
• The Chordates
• Tunicates
• Lancelets

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ACEOLOMATES
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The Sponges

• Phylum Porifera
• The Sponges
• Hermaphrodite, sessile animals
• They have no nerve or muscle tissue but
  individual cells can react to environmental
  changes.

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The Cnidarians

• Phylum Cnidaria
• There are four classes of this phylum
• HydrozoaHydra
• CubozoaSea worms
• ScyphozoaJelly fish
• AnthozoaSea anemones
• Organisms have cnidocytes
• Organelles with stinging abilities
• Organisms have nerve cells that are irregular and
  non-directional.
• Occurs in two forms
• Polyps
• Medusa

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The Flatworms

• Phylum Platyheminthes
• Most are hermaphrodites that are free living or
  parasitic.
• Organisms have sense organs and a simple brain
• Include tapeworms

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PROTOSTOMES
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The Roundworms

• Phylum Nematoda
• These organisms are normally associated with
  being parasitic or pests.
• Parasites
• Hookworms
• Pinworms
• Agricultural pests
• Attacking plant roots

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The Segmented Worms

• Phylum Annelida
• Organisms have large compartmentalized coelom
  that serves as a hydrostatic skeleton.
• Includes the leeches and earthworms.
• Earthworms have setae which are bristles composed
  of chitin.

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The Mollusks

• Phylum Mollusca
• Soft bodied animals usually covered by a shell
• Organisms have a ventral foot, which is necessary
  for locomotion, and have rasplike radula which
  functions as a scraper in feeding.
• Include squids, octopus, snails and slugs.

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The Arthropods

• Phylum Arthropoda
• These organisms are segmented animals with
  jointed specialized appendages.
• The organisms have exoskeletons that are composed
  of protein and chitin.
• Include the centipedes, millipedes, lobsters,
  crabs and insects.

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DEUTEROSTOMES
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The Echinoderms

• Phylum Echinodermata
• These are sessile slow moving animals that have
  spiny skin.
• Included are the sea lilies, sea stars, sea
  urchins, brittle stars and sea cucumbers.

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Phylum ChordataSubphylum Urochordata

• Tunicates
• Suspension feeding, marine animals with tunics
• Larvae have typical chordate characteristics
• Free swimming
• Adults of most groups are sessile suspension
  feeders

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Phylum ChordataSubphylum Cephalochordata

• Lancelets
• Small segmented, fishlike animals that exhibit
  chordate characteristics

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Characteristics of Common Animal Phyla
Phylum Sample Animal Acoelomate Pseudo-coelomate Coelomate Symmetry Number of Germ Layers
Porifera Sponge X Radial 2
Cnidaria Hydra X Radial 2
Platyhelminthes Planaria X Bilateral 3
Nematoda Roundworm Pinworm X Bilateral 3
Annelida Earthworm X Bilateral 3
Mollusca Slug Clam X Bilateral 3
Arthropoda Insect Spider X Bilateral 3
Echinodermata Starfish Sea urchin X Bilateral 3
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REVIEW
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Review I