Good observation. Tidepools can be saltier
than the ocean because of evaporation. We
call it evaporation when water (or anything
else) changes from a liquid to a gas. Things
that are dissolved in water, such as salt, don't
evaporate at the same temperature as water, so
they are left behind. Now there's the same amount
of salt, but less water to dissolve it in, so it's
Did you know that the Great Salt Lake in
Utah is so salty that you float in it instead of
sinking? It's so salty that the only animals
that can live in it are brine shrimp (sea monkeys)
and brine fly larvae. The amazing thing is that
the Great Salt Lake is not the remains of an
ancient ocean. It is fed by fresh water, which
contains a tiny amount of salt. There's no outlet
from the GSL; all the water that leaves
evaporates, leaving the salt behind. In flood
years, the salt content is about 5%. In drought
years it's about 10%. Compare this to the 3%
salinity of the ocean. How many times saltier
is the Great Salt Lake?
Adding heat speeds up evaporation. Do you
think that the saltiness of a tidepool will depend
on the weather or the time between high tides?
Do you think this is a problem for animals in
Thanks for asking.
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