LIFE AQUATIC
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spring 2014
vigor and variation, and exposure to stressful conditions
to select for hardiness.
2
Immortal Corals
Poets and philosophers have commented on the
fact that the brevity of a flower’s existence makes its
beauty more precious. We may feel the same way
about corals, but this notion is deceptive. Compared
with corals, we are the cut flowers. Corals can live for
centuries, and the ability to form clones helps ensure
the survival of a genetic “individual” against many
types of accidents. A reef that loses 90 percent of
its coral cover may not have lost a single individual.
Extreme events sometimes kill most or all members
of a particular clone or species on a reef, but it is not
correct to equate coral cover to coral numbers.
Coral Chimeras
Sometimes an individual coral is not an individual
but the product of two or more genetically distinct
corals that have fused — a chimera. Corals offer
a unique perspective into the process of immune
response as they sometimes form chimeras when
planula larvae settle next to each other, fuse and grow
as one individual. Chimeras may also result from
chance fusion between compatible neighbors. They
not only don’t fight but may even benefit from genetic
exchange.
Coral Fluorescence
Illuminating a coral with blue, green or ultraviolet
light produces a fantastic show of color due to the
presence of fluorescent proteins. Corals are typically
shades of brown, blue or purple with a little green
fluorescence, but in some places they have patterns in
brilliant fluorescent green, red and orange, the product
of mutations in the expression of green fluorescent
protein. The purposes of the fluorescent colors are
not fully known, but the colors impart charm and
attractiveness to the corals, which enhances our
appreciation of them. We select, cultivate and thus
perpetuate fruit trees and ornamental plants for
similar charms.
Corals in Captivity
Corals are now easily grown and propagated,
like houseplants, in aquariums all over the world
in artificial seawater far from the sea. Is it an
exaggeration to say that these corals have migrated
inland in advance of a coming sea-level rise? Is it a
stretch to imagine that corals love us, too? Or are they
just using us, charming us with their beauty, as a way
to perpetuate their survival?
AD
References
1. Veron JEN. Corals In Space and Time: The
Biogeography and Evolution of the Scleractinia (Ithaca,
N.Y.: Cornell University Press, 1995.)
2. Sprung J. Accidental Selection: How chance plays a
role in the survival and evolution of aquatic creatures.
Coral, 2011; 8(4): 52-64.
The polyps of this
Clavularia soft coral from
Indonesia have brilliant
fluorescent pigment.
COLIN FOORD
