Migrating Fish
Many species of fish do reproduce in freshwater, but spend most of their adult lives in the sea. These are known as anadromous fish, and include, for instance, salmon, trout and three-spined stickleback. Some other kinds of fish are, on the contrary, born in salt water, but live most of or parts of their adult lives in fresh water; for instance the eels. These are known as catadromous fish.
Species migrating between marine and fresh waters need adaptations for both environments; when in salt water they need to keep the bodily salt concentration on a level lower than the surroundings, and vice versa. Many species solve this problem by associating different habitats with different stages of life. Both eels, anadromous salmoniform fish and the sea lamprey have different tolerances in salinity in different stages of their lives.
Read more about this topic: Freshwater Fish
Famous quotes containing the words migrating and/or fish:
“It is as when a migrating army of mice girdles a forest of pines. The chopper fells trees from the same motive that the mouse gnaws them,—to get his living. You tell me that he has a more interesting family than the mouse. That is as it happens.”
—Henry David Thoreau (1817–1862)
“The beasts, the fishes, and the winged fowls
Are their males’ subjects and at their controls:
Man, more divine, the master of all these,
Lord of the wide world and wild watery seas,
Indued with intellectual sense and souls,
Of more pre-eminence than fish and fowls,
Are masters to their females, and their lords:
Then let your will attend on their accords.”
—William Shakespeare (1564–1616)