Friday, October 23, 2020

Animal Kingdom - Notes | Class 11 | Part 11: Hemichordata

4. ANIMAL KINGDOM

PHYLUM HEMICHORDATA: GENERAL CHARACTERS

Hemichordata was earlier considered as a sub-phylum of Chordata. Like chordates, it has pharyngeal gill slits.
  • Grades of organization:
    • Organ system.
  • Symmetry:
    • Bilateral.
  • Germ layers:
    • Triploblastic.
  • Coelom:
    • Coelomate.
  • Habit and habitat:
    • Exclusively marine.
  • Digestive system:
    • Complete.
  • Respiratory system:
    • Gills.
  • Circulatory system:
    • Open type.
  • Reproduction:
    • Dioecious.
    • External fertilization.
    • Development is indirect.
  • Unique features:
    • Worm-like cylindrical body formed of anterior proboscis, a collar and a long trunk.
    • Collar bears stomochord (a rudimentary structure similar to notochord).
    • Excretion by Proboscis gland.
  • Examples:
    • Balanoglossus (Tongue worm), Saccoglossus.
============

👇 Select Your Topic Here 👇

No comments:

Post a Comment