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Estuary life
An estuary is the wide part of a river where
it nears the sea. When the tide comes in,
salt water flows into the estuary. When the
tide goes out, the estuary contains mostly
fresh water from the river or stream that
flows into it. Mangrove trees like these are
able to live in the changing estuary water.
Salty seas
The world’s oceans are salty
because they contain a lot of
dissolved chemicals that scientists
call salts. Drinking water also
contains salts, but only in small
amounts, so you can’t taste them.
Surviving in salt water
Countless animals live in water.
They don’t drink, but take water
into their bodies in other ways.
Fish often absorb water as it
washes in and out of their gills.
Salt-water fish absorb only
a little of the salt.
The Dead Sea
contains so much salt
that people can just
float on the surface.
Your body is approximately 66 per cent water.
Put an egg in a glass of
water. The egg will sink.
Start stirring in salt until
the egg rises. The egg will
eventually float because
salt water is denser than
fresh water.
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Fresh and salt water
