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Eel
Eels migrate from fresh water to salt water to have
their young. Eel larvae move across the ocean with
ocean currents, and young eels then migrate up rivers
and streams. After many years in rivers, the eels grow
into adults. Then they migrate back to the ocean to
breed. They become silver so that they are hidden
from ocean predators. Some eels migrate up to
8,000 kilometers across the ocean before breeding.
Sea Turtles
Sea turtles migrate
thousands of
kilometers to breed.
Scientists think that
many turtles go back
every year to the same
place to lay their eggs.
How do they know where
to go? Scientists think that
they follow Earth's magnetic
field. The turtles lay their eggs on land,
and they cover them with sand. They then swim away
to the places where they feed. When the eggs hatch,
the young turtles dig their way out of the sand. They
then go to the ocean and swim away.
When adult eels move from
fresh water to salt water, their
stomachs become smaller and
their eyes become much bigger.