Each animal phylum has a unique body plan.

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Each animal phylum has a unique body plan.

• Vertebrates have an internal segmented backbone.
• Invertebrates do not have a backbone.
• Invertebrates encompass most animal groups.

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Three criteria are used to categorize animals
Protostomes Deuterostomes

• Body plan symmetry
• Bilateral body divides equally along one plane
  (mirror images)
• Radial body arranged in a circle around a
  central axis
• Tissue layers
• Bilateral have 3 distinct layers
• Radial have 2 distinct layers
• Developmental patterns
• Protostomes mouth first, anus second
• Deuterostomes anus first, mouth second

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• Protostomes and deuterostomes are the two major
  radiations on the animal phylogenetic tree.
• Based on anatomical and molecular evidence

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Porifera

• AKA Sponges
• Most primitive animals
• 570 myo, gt9000 species
• Specialized cells, but no true tissue
• Closely related to protists
• Neither protistomes or deuterostomes

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Shared characteristics

• Sessile
• Filter feeders
• Specialized cells include
• Spicule skeletal like cells spongin, silica,
  or CaCO3
• Pinacocytes outer layer
• Choanocytes inner layer, each has a flagellum
• Amoebocytes middle layer, absorb and digest

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Sponge Reproduction

• Reproduce sexually or asexually
• Sexual
• Hermaphrodites, producing eggs/sperm at different
  times
• Sperm is released, captured by female of same
  species
• Ciliated larvae form from zygote
• Asexual
• Budding small piece breaks off, but can still
  survive

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Cnidaria

• AKA Stinging nettles
• Nematocyst capsule with a poison barb at one end
• gt 9000 aquatic species
• Mobile
• Two body forms
• Polyp
• Medusa
• Gastrovascular cavity

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Cnidarian Reproduction

• Sexually mostly medusa-
• Gametes released in water
• Zygote develops into free-swimming larva, called
  planula
• Asexually mostly polyps-budding

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• The four major cnidarian classes are defined by
  their dominant body form.

• Anthozoans such as sea anemones have a dominant
  polyp stage.
• Hydrozoans such as hydra alternate between forms.
• Scyphozoans are jellyfish with a dominant medusa
  form.
• Cubozoans such as sea wasps have a dominant
  medusa form.