Question

Explain about hemichordata and chordata phyllum

Answer 1

Answer:

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Phylum Hemichordata. These animals are also called as Acorn Worms. They were initially grouped under Phylum Chordata. But, research has proven that none of these organisms does not have a post-anal tail or even the notochord, which is a distinguishing feature of chordates.

Answer 2

Answer:

Phylum Hemichordata -

• They are billaterally symmetrical.
• They have organ level system of body organisation.
• They are tripoblastic.
• They are ceolomate.
• They are exclusively marine.
• Their digestive system is complete.
• They have gills in their respiratory system.
• The circulatory system is open.
• They are dioceious.
• The fertilization is external.
• The development is Indirect.
• They have a worm like cylindrical body.
• Their body is formed of anterior proboscis a collar and a long trunk.
• Collar bears stomo chord.
• Excretion happens by Proboscis gland.
• Example - Balanglossus and Soccoglossus.

Phylum Chordata -

• The presence of notochord at some stages of life cycle is a special character of chordates.
• In some lower chordates, the notochord can persist throughout the life.
• In some higher chordates, it gets replaced by vertebral column.
• They have the presence of dorsal hollow nerve chord.
• Its enterior part develops into brain.
• The remaining part of dorsal hollow nerve chord develops into spinal cord.
• They have the presence of paired pharyngeal gill slits.
• In embryonic stages, there is a presence of gills and tail.
• The gills remain throughout the life in only fishes whereas it dissapears in other chordates.
• The tail also dissapears in some other adult chordates.