Phylum : Cyclostomata, Notes, Examples & NEET MCQs (Class 11 Biology)
Definition / Introduction
- Cyclostomata are primitive vertebrates and having circular mouth ๐ but absence of jaws.
Hum isse pehle ki post main Protochordata : Urochordata and Cephalochordata ko vast study ke sath complete kar chuke hai.
- These are primitive, aquatic Vertebrata belong to class Agnatha( absence of jaw ).
- They have eel like bodies , without scales but having no paired fin . They have Dorsal and caudal fin.
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General Characters
- All members of cyclostomes are ectoparasite on some fish ๐.
- They have elongated body with six to fifteen pairs of gills slits for respiration ๐ซ.
เคตिเคทเคฏ เคธूเคी (Table of Contents)
- They have circular and sucking mouth ๐ without jaw.
- Body is not covered by the scales ♎ and paired fins are absent.
- Notochord is replaced by the cartilaginous vertebral column. Cranium is also cartilaginous.
- Heart has two chambers and circulatory system is closed type
๐ Video Topics & Timestamps
- 0:00 Introduction to Cyclostomata
- 0:45 Body & Habitat (NCERT)
- 1:30 Sucking Mouth (Jawless Features)
- 2:15 Respiratory System: 6-15 Gill Slits
- 4:00 Migration: Marine to Fresh Water (Imp!)
- 5:45 Examples: Petromyzon & Myxine
* Click on time to watch that part in video.
- Animals are marine but migrated into fresh water for spawning. After spawning they die after few days and their larva return to ocean after metamorphosis.
Extra shot of general character
- Mouth bear teeth and moved by protractor and retractor muscles.
- Digestive system has no stomach and oesophagus is directly open into intestine.
- Brain is well developed with 10 pair of cranial nerve.
- A pair of mesonephric kidney are present for the Excretion.
- Life cycle of cyclostomes have Amocoeate larva which is transformed in to adult after metamorphosis.
Example of Cyclostomata
Petromyzon ( Lamprey)
- It is commonly called as lamprey.
- Body is elongated. Mouth is circular and sucking with large and sharp teeth.
- Skin is soft, smooth without scales but has with unicellular mucus gland on skin.
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| Petromyzon ( Lamprey) |
- It has no paired fin but a median fin is present.
- It has six to fifteen pairs of gills slits for respiration.
- Lamprey are ectoparasite on some large fish.
๐ก NEET KEY POINTS
๐ Cyclostomata are jawless (agnatha), primitive chordates with an eel-like body.
๐They have a circular mouth, sucker-like structure, and gills for respiration.
- It is migrated into fresh water for spawning. After spawning they die after few days .
- Vertebral column and Cranium is cartilaginous.
- Circulatory system is closed.
* Swipe left/right to view full table on mobile.
Myxine ( Hag fish)
- It is commonly called as Hag fish and exclusively marine.
- Body is elongated. Mouth terminal , circular and sucking without eyes and jaws.
- Hagfish release slime which affect respiratory system of their predator.
- It has no dorsal fin or reduced dorsal fin.
- It has six to fifteen pairs of gills slits for respiration on both side of body.
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| Myxine ( Hag fish) |
- Hag fish has primitive brain and reduced pineal body.
- It is migrated into fresh water for spawning. After spawning they die after few days .
- Vertebral column and Cranium is cartilaginous.
- Circulatory system is closed.
๐ฏ NEET MULTIPLE CHOICE QUESTIONS
๐ฅ 100% CHALLENGE
"Questions yahi se aayega... taiyari jeet ki!"
1. Cyclostomes are:
A. Endoparasites on most of fish
B. Ectoparasites on most of fish
C.Endoparasites on some fish
D.Ectoparasites on some fish
Answer: D
2. Which one of the following is not a character of Cyclostomata.
A. Upper and lower jaw.
B. Elongated body.
C. Scale less body
D. Circular and sucking mouth
Answer: A
3. How many pairs of gill slits are present on Cyclostomata for respiration.
A. 8 to 10 pairs
B. 6 to 15 pairs
C. 10 to 20 pairs
D. 12 to 24 pairs
Answer: B
4. Which one of the following statement is incorrect for the Cyclostomata
A. They have eel like elongated body.
B. They have circular and sucking mouth.
C. Scales and paired fins are absent.
D. Cranium and vertebral column is cartilaginous.
Answer : C
5. Which one of the following pair is incorrect for the Cyclostomata.
A. Mouth : Circular and sucking
B. Vertebral column : Bony
C.Skin : Smooth without scales
D. Circulatory system: closed type.
Answer: B
6.Cyclostomes are Agnatha , signifies
A. Elongated body
B. Sucking mouth
C. Absence of jaw
D. Scale less body
Answer: C
7. Myxine is
A. Cuttle fish. B. Jelly fish
C. Dog fish. D. Hag fish
Answer: D
8. Which of the following statement is not correct for the Cyclostomata.
A. They are marine but migrated into fresh water for spawning.
B. After few days of spawning they die.
C.Their larva are remain survive into fresh water without metamorphosis .
D. Their larva after metamorphosis return to ocean.
Answer: C
9. Petromyzon is
A. Cuttle fish. B. Jelly fish
C. Dog fish. D. Hag fish
Answer: D
10. Given below is a Diagram of petromyzon. Identify the organ denoted by letter A
A. Tympanum. B. Nostril
C. Gills slits. D. Eye spot
Answer: C
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