The Egyptian pyramids are a monument to human
engineering, preserving both culture and mummies across millennia. But for the purposes of our
microcosmic journey, what’s most remarkable about them are the bits of fossils that made up their
limestone. As far back as the 5th century BCE, the Greek historian Herodotus noticed
these shells embedded in the pyramids. What he did not know is that these shells
were the remnants of creatures that are just as intriguing as the pyramid’s own inhabitants.
In the early 19th century, far removed from those pyramids, a young boy named Alcide d’Orbigny
would become fascinated with the tiny shells he found on the beach. And when he grew up and
expanded his hobby into a more professional study, he named them and the organisms they
came from. He called them foraminifera. If you judge them just from appearances, it might
be a surprise to learn that foraminifera is an amoeboid protist, meaning that
inside that hard shell--which is also called a test--there is a squishy amoeba.
While we don’t know too much about how foraminifera evolved from other eukaryotes,
we know that they’ve been around for over 500 million years. And over that time, they’ve
evolved at least 10,000 species that are still living today and another 40,000 species
that we know only through their fossils. There are two different main types of
foraminifera. Most of the living species we know are benthic foraminifera, which means
they’re found throughout the ocean’s depths, living on rocks and seaweed or just the ocean
floor. They’ve even been found in abundance in the Challenger Deep, the deepest known point in
the ocean. The second group are the planktonic foraminifera, which float on or near the surface
of the ocean thanks in part to their tests. Both types of foraminifera make and inhabit
tests. And scientists can use the materials and test morphology to distinguish between
different species. Some foraminifera secrete compounds like calcium carbonate, while
others glue bits of inorganic particles together with the organic equivalent of cement.
And inside, the tests are divided into chambers, with some species creating complex structures out
of these chambers the way we might create complex arrangements of rooms in a building. Foraminifera
are architects, and as they grow, they build more chambers to accommodate themselves. Some grow
so fast they have to add a chamber every day. The shapes of these chambers play a particularly
crucial role for planktonic foraminifera, which generally build less complex structures
compared to their benthic counterparts. The chambers they build are more globular,
which provides the planktonic foraminifera with a means to stay buoyant as they float around.
But foraminifera, or “forams” as they call them in the biz, don’t just build shells, they also build
webs. Or more accurately, they become webs.The foraminifera tests are lined with holes that
act like little windows to allow the organism’s pseudopodia, or “false feet” to peek out.
And “peeking” might be an understatement. The pseudopodia reach and reach out,
forming their own webs as they do to find food and catch it. These forms of pseudopodia
are called reticulopodia, and you can see here just how weird and extensive they are in action.
They may look like a disintegrated spider’s web, but remember that this is the organism
reaching its own body out to the microcosmos, spreading itself thin as it contorts into
new shapes. Zoom in on those reticulopodium, and you can see the cytoplasm streaming
through it like a biological highway. When forams die, the soft matter that makes
up those pseudopodia will eventually decay, but what remains are the tests. And over the
hundreds of millions of years they’ve existed, the death of foraminifera has become
integrated into our planet’s geology. Large swathes of the ocean floor are covered in
the collected remains of planktonic foraminifera, creating a dense substance called Globigerina
ooze. And we owe famous sights like the pink-tinted beaches of Bermuda and the nummulitic
limestone of the Pyramids to ancient foraminifera. And the abundance of these fossilized remains
provides us with a record of our planet’s history. While forams may be found throughout our oceans,
individual species have their own environmental needs, whether that means they prefer a particular
temperature or salinity or light condition. So assessing the fossil composition of different
sediments helps scientists understand what our world once looked like. And understanding
the past shapes our present as well, with oil companies using microfossils to understand
the geology of the area they’re working in. So where did our fossils come from? Well, they
had a bit of a journey. James, our master of microscopes, got these samples from Virginia by
way of his fiancée, who collected water and sand from the coast and packed them in a jar.
If that seems like an easy enough way to give the lovely gift of microbes to a
microscopist, just remember that she had to take the samples from Virginia to Poland.
And that’s where things started to go wrong. First the jar of sand and water leaked all
over her luggage. Then after she arrived, James’ cat tipped over the jar, as cats do like
to do. But we cannot blame the cat for all the subsequent damage either because James also
tipped the jar over while trying to open a window. On the one hand, this story seems like something
of a cautionary tale on the importance of careful jar handling. But even after
having lost all that water, the jar was still full of sand—and also what turned out
to be a whole bunch of foraminifera fossils. And maybe that’s the true lesson to
take from our shelled, amoeboid friends: that even when the world around them has
tipped and turned and leaked, even then you can find something dazzling in what remains. Thank you for coming on this journey with us as
we explore the unseen world that surrounds us. And thank you to everyone who has so
far backed our Kickstarter project of the Microcosmos microscope. We’ve blown
past our goal and I’m very excited that we’ll be sharing these with you. I’ve really
been enjoying mine. I need to make my technique better because I’ve actually hurt
my neck a little bit looking into it so much. Thank you also of course to all of our patrons
on Patreon. These people whose names are on the screen right now. These folks are the reason
we are able to make Journey to the Microcosmos. Everyone of you, thank you so much
for giving us this opportunity to make stuff for you and for everyone.
If you want to see more from our Master of Microscopes James Weiss, you can
check out Jam & Germs on Instagram, and if you want to see more from us, there’s
always a subscribe button somewhere nearby.
