In seconds,
its teeth will cut through your skin.
Its suckers will stick into your raw meat,
draining blood from your body.
And there are millions of them!
Could you survive this?
Let's see.
There are about 650 species of leeches.
They can be as small as 15 mm (0.6 in) long
or as large as 45 cm (18 in,)
like the Giant Amazon Leech.
They have a sucker
on both ends of their body.
One of them contains the mouth,
which secretes a strange type of saliva
that numbs its prey.
So, you won't even notice
when they bite into you
and start sucking your blood.
The saliva will also dilate the blood vessels
to increase blood flow,
so they can drink and drink again,
until they quench their thirst for blood.
The average pool holds about
28,000 liters (6,400 gal) of water.
But this time,
the pool is filled with nine million
thirsty leeches.
So, don't make any sudden moves.
Leeches use the disturbances
in the water to find their victims.
Juveniles generally attach to fish
and amphibians.
But adult leeches,
like these ones,
prefer luscious, juicy mammals,
like you.
So, hold your breath
and don't move.
Leeches eat slowly,
so it takes them up to 45 minutes
to quench their thirst.
And they carefully choose
where they will bite you.
They typically target the groin,
between the toes,
armpits,
and hard-to-notice crevices.
And remember,
their numbing saliva
will prevent you from feeling the bite
and realizing that leeches
are draining your blood.
They can even get stuck
inside your mouth and nostrils
and kill you by suffocation.
So, cover your crevices
and don't open your mouth.
A human adult has about
5 liters (1.3 gal) of blood
in their body.
An adult leech drinks
5 to 15 ml (0.84-2.5 tsp)
of blood per meal.
It can take over 300 of these
little bloodsuckers
to suck you dry,
but humans can't live
after losing 40% of their blood.
So it would only take about
120 leeches to kill you.
In 2008,
a 65-year-old man in Turkey
rushed to an emergency room
due to unstoppable bleeding.
Doctors found 130 leech bites
all over his body.
Fortunately, the man survived
after receiving eight units
of frozen plasma.
Would you mind counting
how many leeches have already
attached to your body?
Don't panic and try
to rip them off your body
as they hook into your skin,
which would seriously hurt you.
Common remedies include putting salt,
lemon,
or fire on them to force them off,
but that would make them vomit on you,
and possibly infect you with bacteria.
Instead, find the leech's mouth.
It's on the thinnest part of its body
Use your fingernail, credit card,
or a sharp object
and gently push the mouth
out of your body.
Then wash the wound
and apply alcohol or hydrogen peroxide
to prevent an infection.
If you're swimming,
and water splashes into your mouth
or nose,
leeches can enter your body
and feed on your blood.
In Africa,
people have died from anemia
caused by drinking leech-infested water.
In 2004,
a 15-year-old girl in Tanzania
had severe anemia
and cardiorespiratory distress.
After three days in the hospital,
she vomited,
and a small water leech came out.
Doctors concluded that she drank it
from a leech-infested water source
without even realizing it.
After barfing out the leech,
she began to recover.
So, don't take a single sip
of questionable water.
OK,
that was scary,
but you made it out alive.
Now, you definitely
need to take a shower.
What?
There's no water.
Now what?
Could you survive
without showering for a month?
Let's find out.