Times of the Islands Winter 2022/23

green pages newsletter of the department of environment & coastal resources
From top: If you look closely, you can spot a baby flamingo tongue
snail. Research suggests that the gorgonian-munching flamingo
tongue snail helps cultivate the diverse community structure of
healthy reefs by creating space for other types of coral to settle.
but thrive on their poisonous diet, going so far as to
assimilate the sea fan’s toxicity into their own tissues.
This gives the flamingo tongue a poisonous defense
mechanism against its own predators that its bright-orange
color then advertises. Warning coloration such as
this is referred to as aposematic coloration, and is meant
to signal to potential predators that it’s off the menu.
This is an incredible example of coevolution, a phenomenon
in which organisms evolve in response to each
other, with the flamingo tongue having evolved to thrive
on a diet that its prey had evolved to ward off other grazers,
and to even co-opt its prey’s defense mechanism as
its own. This ancient “evolutionary arms race” is what
we must thank for the beautiful coloration adored by
snorkelers throughout the tropical western Atlantic and
Caribbean.
So, what’s the deal with C. gibbosum: If it is both
a predator and parasite of corals, is it a threat to our
dwindling coral reefs? Or does it play a key role in these
complex coral communities? The answer likely lies somewhere
in the middle.
Research suggests that these gorgonian-munching
snails may help maintain coral reef diversity by creating
space for other types of coral to settle and flourish.
Thus, by eating sea fans and other octocorals, flamingo
tongues help cultivate the diverse community structure
of healthy reefs. However, if there is a change in population
dynamics, this healthy natural balance can be
dramatically shifted, having devastating impacts on sea
fan corals. For example, a 2008 outbreak of C. gibbosum
in Puerto Rico wiped out more than 90% of the sea fans
around the remote reefs around Mona Island.
One factor that can lead to this imbalance is overfishing—despite
the snail’s toxicity, there are species of
fish, primarily pufferfish and invertebrates such as lobster,
that consume it. These snail predators indirectly
maintain coral health by keeping the parasitic species in
check. For example, a study in the Florida Keys found that
C. gibbosum populations in areas where large predators
were removed increased to nearly 20 times their original
size, leading to extensive damage to the sea fans.
Here, the relationship between flamingo tongues,
sea fans, large predators, and the greater coral community
demonstrates the precarious balance of nature, a
precisely interwoven web vulnerable to human-mediated
shifts. While most imagine predation and parasitism as
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