[ELECTRONIC MUSIC]
[ELECTRONIC MUSIC AND SOUND OF WATER DROPLET]
[MICROSCOPE SLIDE CLICKS INTO PLACE]
[BOUNCY, ELECTRONIC MUSIC]
>>SALLY WARRING: My name is Sally. I am a biologist at the American Museum of Natural History
where I study microscopic organisms.
On Pondlife we are going to go on a safari to
explore the microbial wildernesses that exist all around us.
I’m in the middle of Manhattan. I’m at the Harlem Meer in Central Park and I’m
here to look for a particular microbial community.
It’s a community that you might have seen before, but you’ve probably not looked at
it quite like this.
For most of human history, people thought of all life as being plants and animals.
And the fact that species existed that were so small that you couldn’t even see them
was completely unknown.
That all changed in the Seventeenth Century when a Dutch fabric designer named Antonie
van Leeuwenhoek invented the most powerful microscope the world had ever seen.
I have a replica of his microscope in my pocket.
This is it.
This tiny little thing contains a really small spherical glass lens and that
spherical glass lens was capable of magnifying up to 300 times.
So, he would place whatever he was interested in on one side of the lens.
He would look through by placing the microscope right up to his eye.
So using this microscope he became the first person to see unicellular life, and he first
saw that unicellular life when he looked at a community of microorganisms called pond scum.
And I can see a beautiful example right over here.
[BUBBLY ELECTRONIC MUSIC]
>>WARRING: This is great…
This is exactly what we’re looking for.
Beautiful pond scum.
Success!
That pond scum is a growth of filamentous green algae and I’ve put some here on my
Leeuwenhoeck microscope and we’re going to take a look and see what he might have
seen in the pond for the first time.
Leeuwenhoeck learned by looking through his microscope that the pond scum was made up
of green algae that wound together.
But what amazed him the most was that moving amongst that green algae were tiny little creatures.
He called those little creatures animalcules or “little animals.”
These days microscopy and our understanding of microbiology have come a long way.
I have with me a modern-day field microscope.
Rather than a small spherical lens it has an objective.
An objective contains many glass lenses stacked one on top of each other.
We’re gonna take a look at what we’ve got.
At one hundred times magnification we can really see the details of this green algae.
It’s called spirogyra.
[ELECTRONIC MUSIC]
>>WARRING: Each spirogyra filament is one cell thick, about the width of a human hair
Spirogyra gets its name because inside each cell there is a long, thin, green chloroplast
that coils and gives the organism its corkscrew appearance.
Spirogyra, like all algae, live off sunlight.
But when they grow in dense mats like the one in the Harlem Meer the filaments on top
end up shading the ones beneath.
But Spirogyra has a way of dealing with this.
The filaments are able to glide and they stay constantly on the move.
This way each filament will, at least for part of the time, have access to the sun.
Just like Leeuwenhoek we find many microbial creatures living among the algae.
Here there are several species of ciliate.
Ciliates are a diverse group of single-cellular organisms that are covered in small, hair-like
structures called cilia.
Each species of ciliate has a unique arrangement of cilia.
This one has cilia only on the underside of its cell.
It uses the cilia like tiny legs to walk about on the spirogyra.
[FLUTTERING ELECTRONIC MUSIC]
>>WARRING: This is one of the ciliates that Leeuwenhoek was first to describe.
It’s called Vorticella.
Each is an individual bell-shaped cell sitting atop a long stalk.
That stalk is rather special.
It’s a curious coiling contraption that can move like lightning if the cell senses any danger.
[ELECTRONIC PULSES]
>>WARRING: The stalk also keeps the vorticella anchored, so that it can use its cilia
to generate a current in the water.
The cilia are arranged in a ring around an opening in the cell that acts as a mouth.
The cilia beat and drag water, bacteria, and other small microbes right into the vorticella’s
waiting mouth.
This beautiful organism is a heliozoan— "helio-" meaning sun,
and "-zoan" meaning animal.
Though, it’s not an animal at all.
The heliozoan is covered in many spike-like structures called axopodia, which radiate
out from the cell’s surface and act as a net for ensnaring prey.
In real time the heliozoan appears static, but in time lapse it really comes to life.
[CYCLING ELECTRONIC MUSIC]
>>WARRING: A green cell is ensnared...
but makes a lucky escape.
The second cell is not so lucky.
Leeuwenhoek was fascinated by organisms that moved like animals, but were green like plants.
This one is called phacus.
It’s not an animal, or a plant. It belongs to a completely separate group of organisms
called the euglena.
Its movement is due to a long, thin structure called a flagellum that extends out the front
of the cell.
The flagellum beats and pulls the cell through the water.
You can also catch a glimpse of a red spot inside the phacus.
This is called an eyespot.
It sits at the base of the flagellum and can detect the intensity and direction of light.
Like a plant, the phacus lives off sunlight and this eyespot allows it to move through
the water to wherever the light intensity is best.
[LILTING ELECTRONIC WALTZ]
>>WARRING: In that one drop of water we just saw a wide variety of microbial species.
In the whole pond their numbers probably reach into the many thousands.
And that’s only scratching the surface of the amount of microbial diversity
that we could find the world over.
And to really get a handle on this microbial diversity, we’re just going to have to keep exploring.
I’m gonna put these microbes back where I got em from.
[UPBEAT ELECTRONIC MUSIC]