step on the hard corals!
It is important to stop and explain hard corals before entering
the coral rubble and reef area. Do a good 'first station' to sensitise
visitors to the fact that every inch of the shore is alive.
The Zebra hard coral
(Oulastrea crispata) is commonly seen even on silty shores
in the North on stones and rocks. Look out for them and ensure they
are not stepped upon.
What are hard corals?
you guess? Are they animal, vegetable or mineral?
- Yes they
are animals: each hard coral is a colony of many tiny animals
they do appear to be rocks or minerals: each polyp builds
a tiny hard skeleton to live in.
each hard skeleton is covered with a thin layer of living
tissue. So don't touch them or step on them.
they can be kind of considered vegetables too! Many hard corals
contain tiny algae inside their bodies. The microscopic, single-celled
algae (called symbiotic zooxanthallae, pronounced 'zoo-zan-tell-ay')
undergo photosynthesis to produce food from sunlight. The
food produced is shared with the polyp, which in return provides
the algae with shelter and minerals.
corals grow VERY SLOWLY. Some grow only 1cm a year. So a specimen
in that is a metre across can be 100 years old! Even a tiny
one (point to a tiny one) only 1cm may be growing for one
year already. So please don't step on the hard corals.
Hard corals have different shapes and textures. These are the result
of the way the tiny polyps create their tiny skeletons. Use washed
up, dead coral pieces to illustrate different corallite shapes.
corals are important to the ecosystem
corals and you
- Hard corals
are like trees in an underwater rainforest
provide a hard, permanent structure for small animals to shelter
when they die, dead corals are a place for animals and plants
to grow upon.
small animals in turn are eaten by larger animals.
- Hard corals
NEED a good ecosystem in order to thrive. They need clear water
so that sunlight can allow their symbiotic algae to photosynthesise.
Sediments not only cloud the water, but also smother the tiny
- The live
fish trade is a major threat to coral reefs. Many 'live' fish
are caught either by:
fishing, where a bomb is let off in a reef to stun the fish.
fishing, where cyanide is released into the water to stun
methods destroy reefs. And only a few of the commercially
valuable fish are taken. The vast majority of marine life
that is stunned or poisoned are left behind in a devastated
- The aquarium
trade also has an impact as wild hard corals are harvested for
the trade. Although there is some success in captive breeding
of corals, because these grow so slowly, it is cheaper and easier
to harvest wild corals for the trade.
- Coral reefs
will also be impacted by global warming.
waters will cause coral bleaching, a result of the polyps
losing their symbiotic algae.
- As the
antarctic and arctic ice melts, sea levels are expected to
rise faster than corals can grow to keep close enough to the
surface for sunlight.
carbon dioxide in the air will also make seawater more acidic
which will make it difficult for corals to produce their skeletons.
coral myths to dispel
because they are hard, doesn't mean hard corals are tough.
See above the risks due to human collection and global warming.
Explain corals BEFORE you enter the coral rubble area
so that visitors are sensitive to small growing corals and
don't step on things that they think are just dead rocks.
Don't touch hard corals: Living hard corals are covered
in a thin layer of tissue that is easily bruised!
Use dead corals washed up on the shore to explain internal
features, instead of poking living corals.
Don't remove hard corals from their attachment. They
will die. Don't remove mushroom corals from the water.