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Phylum Echinodermata

Phylum Echinodermata. There are more than 5000 species of Echinoderms. Echinoderms have spiny skins. Defining Characteristics. A complex series of fluid filled canals with numerous flexible feeding and locomotory appendages 5 pointed radial symmetry in adult Exclusively Marine

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Phylum Echinodermata

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  1. Phylum Echinodermata • There are more than 5000 species of Echinoderms. • Echinoderms have spiny skins.

  2. Defining Characteristics • A complex series of fluid filled canals with numerous flexible feeding and locomotory appendages • 5 pointed radial symmetry in adult • Exclusively Marine • Body unsegmented • Larvae bilaterally symmetrical • With unique water vascular system • Digestive system complete • Respiration by dermal branchae, tube feet, or respiratory tree • No kidneys • Dioecious • Locomotion by tube feet, and/or arms

  3. External Anatomy

  4. Larval Echinoderms showing bilateral symmetry

  5. Echinoderms Skeleton • Have an internalskeleton of calcium carbonate • Ossicles vary in size and structure and are manufactured by specialized cells

  6. Water vascular system • A separate coelom is used with interconnecting fluid filled tubes and canals • A ring canal circles the mouth and gives off 5 radial canals • The radial canal is exposed and runs along the ambulacral groove

  7. Water Vascular System

  8. Water Vascular System

  9. Tube Feet • The ampullae is a small ball that sits above the tube foot • Contraction and expansion of the ampulla accomplishes movement • They also have a water vascular system that enables them to store water in their tube feet so they can survive while the tide is out.

  10. Mutable Connective Tissue • Another unique Echinodermata characteristic is the presence of mutable connective tissue

  11. Higher ClassificationEchinodermata • Class Asteroidea – sea stars • Class Ophiuroidea – brittle stars • Class Echinoidea – sea urchins • Class Holothuroidea – sea cucumbers • Class Crinoidea – sea feathers

  12. Class Asteroidea

  13. Sea Stars • The oral surface of each arm has a single ambulacral groove • Have a large coelom where all the main organs occur

  14. Sea Star Feeding • Feed mainly on slow moving, sedentary, or sessile invertebrates • Some species evert the stomach onto prey and digest externally, others swallow whole

  15. Pedicellariae • Specialized pinchers found on the aboral surface.

  16. Reproduction • Can reproduce asexually by disk division • Sexual Reproduction • Dioecious with sperm or eggs produced in 2 or more gonads in each arm • Larval stage = bipinnaria

  17. Regeneration • Many species autotomize, leaving predators with a nutritious souvenir while they escape • Most spp. can regenerate from fragments that include the disk

  18. Class Echinoidea • Defining characteristics • Ossicles are joined to form a rigid test • Adults possess a feeding structure called Aristotle’s lantern • Two attributes: mobile spines, and hollow skeleton or test

  19. Aristotle’s Lantern

  20. They use these spines for protection against predators. • The spines also act like stilts to keep their bodies up off the ground so the tube feet can pull them around! • They eat mostly algae. • They live mostly attached to rocky crevices, which protect them from waves and tide surges. • They have become a popular item to eat and are being harvested in alarming numbers.

  21. Sea Urchin Structure

  22. Anatomy of a Sea Urchin

  23. Pedicellariae • Pedicellariae prevent fouling of test and are used in defense • More complex than sea stars and are located on tall moveable stalks

  24. Ingestion and Digestion • Feed on alga material, encrusting bryozoans or scavenge • Food is chopped by 5 sharp pointed teeth • The digestive system is long to deal with vegetable manner • The anus is located aborally

  25. Sand Dollars • Irregular: non-spherical variously depressed • Anus is shifted to the oral surface posterior to the mouth creating bilateral symmetry • The star pattern seen on top of the sand dollars is actually caused by special breathing tube feet! • The mouth is found on the under side of the animal.

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