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Trends in Animal Evolution

Trends in Animal Evolution. Body cavity. Coelomate. Pseudocoelomate. Acoelomate. endoderm mesoderm ectoderm. Trends in Coelomate Evolution. Deuterostomes  Radial Cleavage. Protostomes  Spiral Cleavage. Cleavage. Trends in Coelomate Evolution. coelom. Coelom Formation.

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Trends in Animal Evolution

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  1. Trends in Animal Evolution Body cavity Coelomate Pseudocoelomate Acoelomate endodermmesodermectoderm

  2. Trends in Coelomate Evolution Deuterostomes  RadialCleavage Protostomes  SpiralCleavage Cleavage

  3. Trends in Coelomate Evolution coelom Coelom Formation Deuterostomes Mesoderm forms from outpockets of endoderm; anus forms from opening Gastrula stage ectoderm endoderm Cells migrate from existing cell layers, forming a solid tissue layer which splits; mouth forms from opening Protostomes

  4. 66 - 245 m.y.b.p. The Coelomates Internal body cavities Skeletons (internal and external) 66 m.y.b.p. - present 245 - 540 m.y.b.p. Coeloms & external skeletons The Cambrian Explosion!

  5. The Coelomates Advantages of External Shells/Skeletons Secretion of mineral shell (stores minerals) Protection from desiccation Protection from predators Muscle attachment (locomotion & strength)

  6. Phylum Mollusca

  7. The Cambrian Explosion

  8. Class Caudofoveata Class Solenogastres Subphylum Aculifera Class Polyplacophora Subphylum Conchifera Class Monoplacophora Class Scaphopoda Class Gastropoda Class Bivalvia Class Cephalopoda

  9. coelomates Key Characteristics protostomates mosaic/determinant development mantle head foot

  10. Key Characteristics Cephalization • head is well developed, with one or two pairs of antennae and, in some species, eyes

  11. Key Characteristics radula

  12. Key Characteristics Trocophore and Veliger Larvae

  13. Class Caudofoveata Class Solenogastres (nee Class Aplacophora)

  14. Class Polyplacophora The Chitons • 8 shell plates • mantle “girdle”

  15. Class Monoplacophora

  16. Class Scaphopoda

  17. Class Gastropoda • marine, freshwater, terrestrial • well developed head with eyes and tentacles • torsion

  18. RESPIRATORY SYSTEM Gills Diffusion across skin “Lung”

  19. TORSION BEFORE AFTER dorsal view side view

  20. Class Bivalvia • second largest class of molluscs • mainly marine, with a few freshwater species • no head, no radula, reduced cephalization

  21. Locomotion hydraulics

  22. Bivalve Gills used in feeding and oxygen uptake

  23. Glochidia Dispersal stage unique to freshwater mussels video

  24. Class Cephalopoda squids cuttlefish octopus nautiloids

  25. Key Characteristics • mantle surrounds viscera and forms siphon • ink gland • beak-like jaws • large, circumoral tentacles/arms formed from foot • image forming eyes & large brain • shell present in all except octopods

  26. Rotation of Body Axis

  27. Nautiloid Shell • shell is divided by a series of internal septa • septa are perforated by body extension (the siphuncle) • the siphuncle regulates buoyancy of the chambers siphuncle septum

  28. Cephalopod Locomotion jet propulsion water is forced out of the mantle cavity through a siphon

  29. Visual Communication

  30. Camouflage

  31. mass of squid egg capsules close-up of egg capsules eggs in early stages of development

  32. fertilized eggs late development- stage egg freshly hatched squidlet Direct development of the squid

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