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Echinoderms: Spiny-skinned animals

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Echinoderms: Spiny-skinned animals Section 31.1 Animal Development Echinoderms are related to vertebrates due to their early development The gastrula is the early ... – PowerPoint PPT presentation

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Title: Echinoderms: Spiny-skinned animals


1
Echinoderms Spiny-skinned animals
  • Section 31.1

2
Animal Development
  • Echinoderms are related to vertebrates due to
    their early development
  • The gastrula is the early embryo a hollow ball
    of cells with an opening called a blastopore
  • Other animals are protostomes their mouth
    develops first from or near the blastopore
  • Echinoderms and chordates (vertebrates) are
    deuterostomes their anus develops from the
    blastopore their mouth develops second from
    another part of the gastrula

3
Development, continued
  • First deuterostomes were marine echinoderms
  • Also the first animals to develop endoskeletons
  • Chordates (including all vertebrates) are
    deuterostomes

4
Features of Modern Echinoderms
  • Endoskeleton
  • Calcium-rich
  • Composed of plates called ossicles
  • In adults the plates may fuse and hold spines
    that protrude through the skin
  • Five-part radial symmetry
  • Bilateral symmetry as larvae develop radial
    symmetry as adults
  • Have no head or brain, only a central ring of
    nerves with branches into each arm

5
Features, continued
  • 3. Water-vascular system
  • Made of interconnected canals and hollow tube
    feet
  • The tube feet extend through the ossicles
  • They are used for locomotion and feeding, as well
    as some gas exchange and waste excretion
  • 4. Coelomic circulation respiration
  • The body cavity acts as a simple circulatory and
    respiratory system
  • Skin gills may grow along the spines to increase
    surface area

6
Echinoderm Diversity
  • Sea Stars
  • Mostly carnivores
  • Brittle Stars
  • The largest class of echinoderms
  • Have slender, branched arms
  • Most are filter feeders
  • Sea Lilies and Feather Stars
  • Most primitive echinoderms
  • Their mouth is located on their upper surface
  • Usually sessile

7
Sea Stars
8
Brittle Stars
9
Sea Lilies
10
Feather Star
11
Diversity, continued
  • Sea Urchins and Sand Dollars
  • Lack distinct arms
  • Flattened bodies with protruding spines that may
    have poison
  • Sea Cucumbers
  • Soft and slug-like
  • Ossicles are not fused
  • Sea Daisies
  • Small group, discovered in deep water

12
Sea Urchin
13
Sand Dollar
14
Sea Cucumber
15
Sea Daisy
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