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SUBPHYLUM: VERTEBRATA
CLASS: CYCLOSTOMATA
GENERAL CHARACTERS
1. The body is an elongated eel-like.
2. Skin is soft, smooth and without the exoskeleton.
3. Mouth is rounded, suctorial devoid of functional jaws.
4. Nostril is single
5. Paired fins or lateral appendages are absent.
6. Cartilaginous endoskeleton
7. The notochord is persistent.
8. The heart is two-chambered and aortic arches are many.
9. Single gonad without duct.
10. Development is direct or indirect.
