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In-Depth Information
elvers, their return to the Sargasso Sea as adults to breed is a solitary activity,
with each animal making its own way there.
Some fish migrate only a couple of times in their lifetimes, but other
migrations occur on a more regular annual basis, and some animals migrate
daily, driven by the day length. Some fish living at depths in the ocean make
an upward journey toward the surface as the light begins to fade so that they
can feed in the upper layers. They then return to the relative safety of the
deeper, darker water during daylight hours. Though not all fish that migrate
vertically do so to reach the surface, they may simply move upward to exploit
different feeding levels in the water column.
