Good question. I looked this up on corals.
It said that corals usually grow 0.5 cm to 2
cm per year. But under very good conditions,
they can grow up to 4.5 cm per year. What are
good conditions for coral?
It will help to understand what a coral reef
is. As you probably know the reef is a sort of
apartment building for little animals that are
related to jellyfish. Each little animal forms its
own little cup of hard material that is sort of
similar to what’s in your bones. As the animals
build these little cups, and as new little animals
settle in to start building new cups, the reef
These tiny animals eat smaller animals or food
bits that are in the water around them. They grab
the food with their tentacles and may sting it
with their poison. If there are a lot of waves,
the little animals that build the reef pull in
their tentacles. This means they can’t feed.
Without energy and raw material coming in, there’s
not much growth. So when it is calm, there’s more
reef-building. Big waves can also break pieces
off the coral.
Coral also have microscopic helpers that do
photosynthesis. These are a kind of algae. Like
plants, they use energy from the sun to put carbon
dioxide molecules and water molecules together to
make sugar. The coral use the sugar and give off
the raw materials that the algae need. This is an
example of mutualism, where both kinds of species
get something good from each other. So for good
coral growth, there has to be plenty of light for
The corals also do best if the temperature does
not get too high or low. Different species of
coral have different “favorite” temperatures, but
they do best if the temperature doesn’t change a
Why do you think reefs only grow in shallow
You may want to study marine biology if these
kinds of questions interest you.
Thanks for asking.
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