1. Tardigrade
  2. Question
  3. Biology
  4. Which of the following class is being correctly described by given statements (i - iv)? (i) All living members of this class are ectoparasites on some fishes. (ii) They have a sucking and circular mouth without jaws. (iii) Circulation is of closed type. (iv) They are marine but migrate for spawning to fresh water. After spawning, within a few days they die.

Q. Which of the following class is being correctly described by given statements (i - iv)?
(i) All living members of this class are ectoparasites on some fishes.
(ii) They have a sucking and circular mouth without jaws.
(iii) Circulation is of closed type.
(iv) They are marine but migrate for spawning to fresh water. After spawning, within a few days they die.

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Solution:

Cyclostomata is a group of chordates that includes the living jawless fishes: the lampreys and hagfishes. The name cyclostomata means "round mouths". Their mouths cannot close due to the lack of a jaw, so they have to constantly cycle water through the mouth.