Question

Anadromous fishes migrate from
A. Fresh to fresh water
B. Fresh to marine water
C. Marine to freshwater
D. Marine to marine water

Answer 1

Hint: Cyclostomata are the living members that are ectoparasites on some fishes. They possess bodies that have 6-15 pairs of gill slits that are used for respiration. They have bodies that do not have scales and paired fins. Their cranium and vertebral column are cartilaginous.

Complete Answer:
Cyclostomes are marine vertebrates but they show migration to fresh water for the process of spawning. Spawning means the condition to lay the eggs to give rise to new individuals. After spawning, these fishes die within a few days. Their larvae that remain return back to the ocean after metamorphosis.

Now let us find solution from given options:
- Fresh to fresh water: Osteichthyes are freshwater fishes. Fertilisation is external in these kinds of fishes and they move from fresh to fresh water itself.
- Fresh to marine water: The fishes which live for most of the time in the river and then they migrate to sea that is to marine water for breeding , this kind of migration is termed as the catadromous migration.
- Marine to freshwater: Anadromous migration is termed as the migration of those fishes which spend their most of the lives in sea that is marine water and then moves to river that is freshwater for breeding.
- Marine to marine water: Chondrichthyes that are cartilaginous fishes show internal fertilisation and move from marine water to marine water and show breeding.

Our required option is C that is Marine to freshwater.

Note: Lamprey a kind of cyclostome attaches itself to some fishes and sucks blood from them. At some places, they influence the production of fish, for example Petromyzon, Myxine. The larva of lamprey is termed as the Ammocete Larva. They migrate from freshwater to ocean after the process of metamorphosis.