STAGHORN CORAL
G'day folks,
Reef-building Staghorn Corals are among the fastest growing
corals on the reef; when healthy their branches can grow up to 8 in a year!
They were once very abundant, but their population has declined by over 80% since
the 1980’s, with no signs of recovery.
Quick Facts
- Type: Invertebrate
- Diet: Nutrients from symbiotic algae
- Lifespan: >100 years
- Size: Variable
- Weight: Unknown
- Habitat: Coral reefs
- Range: Bahamas, Florida and the Caribbean
- Scientific name: Acropora cervicornis
Amazing Facts About the Staghorn Coral
Staghorn
Corals are so named because their branches look like antlers. They some of the
fastest growing corals and one of the most important in the Caribbean, having
played a central role in the formation of the reefs over the last 5,000 years.
They provide habitats for a diverse range of marine life and if in good
conditions, can live for hundreds of years.
What are Staghorn Corals?
Staghorn
Corals may look like plants or rocks, but they are actually animals. What we
call ‘corals’ are made up of tiny animals named polyps. They can be as small as
a pinhead or as long as a dart in diameter, and they group together to form
large colonies. They then secrete a hard calcium carbonate shell, which gives
them their ‘coral like’ appearance.
Where are Staghorn Corals found?
Staghorn
Corals live on coral reefs throughout the Bahamas, Florida and the Caribbean.
They inhabit clear waters and are typically found at a depth of 15–60 ft (4.5–18
m).
What do Staghorn Corals eat?
Like many
corals, Staghorn Corals have a symbiotic relationship with single-celled algae
called zooxanthellae, which live in the polyp tissues. They produce nutrients
through photosynthesis which they then pass to the corals. These nutrients are
their primary food source, but Staghorn Corals also prey on microscopic animals
known as zooplankton. Being static, they wait for prey to come to them and then
catch them using stinging cells, known as nematocysts, present on their
tentacles.
How do Staghorn Corals reproduce?
Staghorn
Corals are hermaphrodites, so have both male and female reproductive organs;
they reproduce in two ways: sexually and asexually.
Sexual
reproduction occurs once a year in late summer, and it is quite the event to
witness as eggs and sperm are mass released into the water column all at once.
While each colony produces both sperm and eggs, they don’t self-fertilise, so
sperm released from a different colony fertilises the eggs. The fertilised eggs
then develop into larvae before settling and forming new colonies.
Asexual
reproduction occurs when a broken ‘branch’ attaches to the substrate and begins
to grow once more. As Staghorn Corals are quite fragile, this is the most
common method of reproduction.
Are Staghorn Corals preyed upon?
Staghorn
Corals are fed on by nudibranchs and are also prey for butterflyfish, which
target polyps as well as worms and other small invertebrates. It’s also not
uncommon for certain species of fish, such as parrotfish, to bite off parts of
the coral to reach prey hiding within.
What are the biggest threats to Staghorn Corals?
Staghorn
Coral is listed as Critically Endangered on The IUCN Red List of Threatened
Species.
Climate
change and the associated rise in sea temperature is the biggest threat to
Staghorn Corals as changes in temperature can cause bleaching – when corals
expel their zooxanthellae into the water column. This not only causes them to
lose their primary nutrient source but also their colour as it is the
zooxanthellae that are responsible for the beautiful colourings. Without them,
they are white.
Staghorn
Corals are vulnerable to extreme weather events, which are on the increase as a
result of climate change, and are easily damaged by hurricanes. They are also
susceptible to disease, which can spread quickly and kill off entire colonies,
and at risk from ocean acidification, invasive species and direct contact with
humans, mainly through the fishing industry and tourism.
What is the future for Staghorn Corals?
While
overall numbers of this species are dropping, certain populations are holding
steady. This provides hope that they can recover if we look after them.
Many of
the populations are living in protected habitats, and there are management
plans in place in currently unprotected areas. Some organisations are also
growing Staghorn Corals in nurseries before planting them in the wild.
While the
future of Staghorn Corals is uncertain, possibly bleak, with time and
dedication it may be possible to restore them to their former glory.
Clancy's comment: Amazing what happens beneath the oceans as we get on with our daily lives.
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