Animalia Stupendium: The Giant Clam

Bored with dragons, the wizard Argomandanies turns his arcane attention to the fantastic fauna of the natural world. Welcome to Animalia Stupendium, a chronicle of Earth’s amazing biodiversity with all the enthusiasm of a fantasy monster book. In this episode, the wizard will consider the giant clam!

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Episode Transcript

Speaker 1 (00:03):
Welcome to Stuff to blow your mind, a production of iHeartRadio.

Speaker 2 (00:10):
Welcome to Animalia Stupendium. My name is Argomandanes, former keeper
of the Cauldron, current Quester of the Cauldron. I seem
to have lost it and tireless creature chronicler, and as
you know, mere monsters hold no mystery for me these days. Dracolitches,

(00:35):
I'm sorry to say, are no longer dracolicious. Bore worms
sadly live up to their name, but not in the
way they should. So instead I turn my attention once
more to the strange fauna of a land called Earth.
Travel with me, gentle reader, as we consider.

Speaker 3 (00:55):
The giant clam common name giant plan scientific classic occasion
Tridacna geigis frequency and range. Coral reefs of the South
Pacific and Indian Oceans size up to five hundred and
fifty pounds or two hundred and fifty kilograms, diet filter
feeding omnivores with symbiosis, treasure hoard Tridacna pearls challenge rating two.

Speaker 4 (01:19):
Here in my home, realm giants are a diamond dozen,
as are the gaping mass of underwater creatures. So, my
fellow wizards and witches might think me quite mad for
my latest terrestrial obsession. For the waters of Earth, particularly
the shallow coral reefs of the South Pacific and Indian oceans,

(01:43):
offer up a creature that is significantly smaller than a
hill giant and completely incapable of swallowing a man whole. Ah,
But that last fact has long eluded the people of Earth.
Many are their tails of human divers whose arms become

(02:05):
trapped in the rapidly closing shells of a giant clam,
or of those jar like shells closing up over their
entire bodies, swallowing them whole. Certainly, things of this nature
occur every day in my own realm of the fantastic,
but not so in the waters of Earth. For assuredly,

(02:26):
while various folk traditions, tall tales, and Hollywood movies warness
of such killer clams and man eating clams, there is
no verified account of a giant clam ever, claiming a
human life wisdom check success. For while various accounts speak

(02:48):
of their shells closing on the human arm that reaches
into steel their pearl, the fact of the matter is
that a giant clam simply does not close its shell
with enough speed to catch. Certainly, smaller clams may snap
their shells closed with haste, but for Tridacna geigis, it's
just too much mass to move in too short a time,

(03:11):
and adults cannot even close their shells completely. Yet the
stories persist, perhaps in large part because the clam shells
a pair of calcareous shells or valves joined near a
hinge with a flexible ligament simply remind us so much
of a mouth, something these organisms don't exactly have. Instead,

(03:33):
they have a pair of siphons, one for drawing in
water and food, another for expelling waste. Furthermore, they are
filter feeders and have no need for any jar like mechanics.
They simply close or in this place nearly close their
shells for protection. But alas perhaps human beings are just

(03:54):
hardwired to see a gaping mar that might bite or
swallow them. It is a matter of survival even when
the threat does not actually exist. Oh and on the
subject of their treasure, Yes, Tridacna pearls, they do in
fact produce these. Like all pearls, they are products of
abnormal growth, generally due to an infection, and as they

(04:18):
can grow to quite large size, they can prove quite valuable,
but only to humans, of course. The giant clam, however,
is more than worthy of our attention, though regardless of
its pearls or whatever tall tales may circulate about its
purported bite. Again, it is nothing short of the largest

(04:40):
bivalve mollusk in the ocean, and the tissue within their
shells often takes on rather colorful hues blues, greens, and
yellows that may seem to hypnotize the humble snorkeler and
bring to mind fabrics of earthly wealth or other worldly splendor.

(05:01):
The varied colorization of these mantle tissues is, of course,
not a magical affair, but rather iriticide cells. It feed
light to symbiotic single celled dinoflagellate algae or zoazanvella, and
it acquires the sohasanthella via its constant filter feeding in

(05:22):
the water, along with plectonic organisms that it actually eats. Thus,
during the day, the clam opens wide and extends its
mantle tissue to absorb the sunlight necessary for the algae
to conduct photosynthesis. In return, the algae produced sugars and
proteins that the clam needs to survive, along with its

(05:47):
more traditional filtered diet, which it requires less of. Speaking
of light, the giant clam also boasts thousands of pinhole
eye spots along the mantle's head that allows it to
detect changes in light, not only the cycles of night
and day, but the tail tale shadows of approaching predators,

(06:09):
of which it has many, and thus it may close
or nearly close its shell, though again not with enough
speed to capture a human being or a human limb.
While Tradacna geigis is the largest, there are other species
of giant clams as well, in the Tradacna genus, which

(06:30):
stems from the Latin for three bites. Going back to
the writings of Pliny the Elder and even the conquest
of Alexander the Great, it was said that these clams
supplied such meat as to require not one, not two,
but three bites to consume. And humans certainly consume them,

(06:54):
not merely for their meat, but also for their pearls
and their enormous shells, and I've done so with enough
gusto to make the organism critically endangered. This is, of
course a threat not only to the giant clams, but
to the robust and delicate coral reef environments, where they
serve as reef builders, water filters, and ultimately sources of

(07:19):
both food and shelter for other life forms in the reef.
There are more mysteries concerning the giant clam to consider,
but for now I must retire my wizard's quill and
allow my familiars some respite. But I shall return with
even more wonders of the natural world.

Speaker 3 (07:46):
Hi, this is Robert Lamb. Thanks once more to the
Wizard Argomnnines for joining us in this episode. Sources for
this episode included The Secret Life of Clams by Anthony D.
Fredericks twenty fourteen, the websites of the University of kane
Bridge Museum of Zoology as well as the Florida Museum,
and the writings of Plenty the Elder the Natural History

(08:08):
and I'd also like to thank the guides and hosts
at Missoul Resort in raja Ampat, Indonesia who introduced me
to giant clams in the wild, including the specimen known
informally there as Wu Tang clam. Thanks as always to
the excellent JJ Possway for producing this episode. If you
wish to contact Argomdines with recommendations for future episodes. You

(08:29):
can send an email to contact at stuff to Blow
your Mind dot com.

Speaker 1 (08:38):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you listen to your favorite shows.