Differences between Acraniata and Craniata


S.N Acraniata Craniata
1. They are exclusively marine. They are aquatic or terrestrial.
2. They are small sized chordates. They are mostly large sized vertebrates.
3. Appendages, cephalization and exoskeleton are absent.  Appendages are two pairs usually, well developed head and exoskeleton present.
4. Coelom is enterocoelic, budding off from embryonic archenteron. Coelom is schizocoelic, arising by splitting of mesoderm.
5. Notochord persistent. Notochord is not persistent i.e. covered or replaced by vertebral column.
6. Skull, cranium and vertebral column are absent. Skull and cranium well developed.
7. Pharynx with permanent gill clefts. Pharyngeal gill clefts persist or disappear.
8. Endostyle is present. Endostyle is absent.
9. Heart chambers less when present. Heart made of 2, 3, or 4 chambers.
10. Red blood corpuscles in blood are absent. Blood contains RBC.
11. Kidneys are protonephridia. Kidneys are meso or metanephridia.
12. Sexes are separate or united, reproduction asexual. Sexes are separate. Only sexual reproduction.
13. Gonoducts usually absent. Gonoducts always present.
14. Development is indirect with a free swimming larval stage. Development is indirect or direct, with or without a larvae stage.

Differences between Acraniata and Craniata

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