oh my God waa that's huge is he biting
all the way through there a blood
sucking parasite that's been used
medicinally for Millennia the bane of
every tropical Pond swimmer there's
another one there's another one here oh
man everywhere oh my God these guys have
mostly evolved to quietly suck blood
without alerting their prey but in some
cases they can kill their Host this is
not what I signed up
for
tonight at the leech restaurant I'm
what's on the
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menu hi I'm danal defo and you're
watching animal logic today the day that
I become leech
food leeches are are the epitome of
parasites their name can be used as a
verb meaning to take without giving
anything in return and for the most part
they have earned their reputation about
3/4 of the 680 known species are blood
suckers this guy was trying to get into
my pants most of them live in fresh
water but there are also marine and
terrestrial leeches oh my God some of
the terrestrial parasites have a taste
for human blood as our trusty producers
found out
firsthand last year we traveled to the
great alwe National Park in Australia to
film
koalas while walking the trails Andreas
and Dylan both began feeling a little
itchy after checking their socks they
found multiple guests Australian land
leaches he's squirming around there's
one coming towards you
br there is nothing behind and but it
was like that oh my God wo that's huge
is he biting all the way through there
this is insane I haven't gotten any on
me but uh Dylan and Andreas have been
covered Andreas just PL plucked off
about five of them smell
delicious the sucky boys wait patiently
on vegetation and when a mammal walks by
they look for the warmest spot attach
themselves and then bite
can I see your bite yeah the thing about
leech is they have three three big teeth
oh so I can't really see where it bit
you but you might have a cool
bite unlike other blood suckers like
mosquitoes these leeches have jaws and
when they bite they make a v-shaped
incision leeches Hold On by using both
suction as well as three really
powerful uh very hook-like teeth teeth
in their
mouth so you can always identify a leech
bite by the shape of those
incisions very sci-fi creature you know
leeches inject an anti-coagulant called
herodin it's one of the world's greatest
blood thinners and makes it easier to
absorb the blood most of their hosts
don't even notice the initial
bite there's another one there's another
one here oh man they're everywhere oh my
God in our case we didn't even notice
until probably hours after they first
bit
us got another one ah okay oh he's just
crawling right up he's he's out your
hand listen he smells your blood
okay I need to get checked now they're
probably falling all over me
too this is not what I signed up
for after the leech is full it detaches
because of the herodin the host can
bleed for hours if not days after
afterwards back where I live in Ontario
we don't have terrestrial leeches we
just have aquatic ones that you find in
the in all the riversides and all of our
Lakes but here they will just wait on a
big blade of grass stretch out and grasp
onto you seeking out your warm hot
blood but of course the vast majority of
leeches are found in water
they've evolved to occupy ecological
niches on all seven continents including
Antarctic Waters and like their
terrestrial cousins most of them are
blood
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suckers here in North America we have
about 80 freshwater leech species
they're so common that they're often
used as fish bait researchers at the
Royal Ontario Museum are even still
finding new
species since I work work there as a
scientific illustrator I got to go and
catch up with the leading leech expert
who recently discovered a new species of
leech so my name is Sebastian kist I am
the curator of invertebrate zoology
which means that I take care of all the
animals that lack a backbone things like
these guys like smaller worms I deal
with the jellyfish Crustaceans and
everything like that it was time to feed
his lab's leeches so naturally I
volunteered to be their snack
tonight at the leech restaurant I'm
what's on the
menu it took a couple of tries but after
a little while one bit these are macrob
Dela Decora North American medicinal
leeches they're usually found in
slow-moving rivers and ponds they
usually consume small vertebrates blood
as well as frog eggs they also readily
feed on human
blood so I definitely felt this guy bite
but it was such a tiny sensation um he
just kind of latches onto your skin with
his teeth and make sure that he can hang
on as he is right now so that he can
suck into my blood for a good 45 minutes
to get full he can grow up to 10 times
his regular size once he's uh gorged
himself on enough blood in this case I
was happy to feed her but what if you
wanted to remove one from your body
leeches as far as we know don't spread
any diseases but one of the things that
can happen is that they throw up a bit
of the blood into the wound and it
brings with it a bunch of bacteria you
might get a minor infection and a good
way uh to get a leech to do that is to
stress
it this means don't put lime or salt on
them it stresses them out there's a
safer
way yeah basically uh you you go in with
your fingernail right by the mouth and
you lift it off off really quickly oh
that's a good way of that's a good way
of getting a leech off of
you but don't worry about me a single
leech would be completely
harmless so a leech like this will
consume about 5 to 10 mL of blood in
about 45 minutes in a complete feeding
so roughly 200 leeches might be a
problem but one of these it's
nothing you can spare 5 to 10 mL you
know once they're connected they don't
care about anything else they have two
Nerf centers one around each sucker but
while they bite all their energy goes to
their feeding end the rest of their body
goes on
autopilot it's like have you ever
tickled a leech cuz I'm tickling a
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leech you might also notice that they
seem to get wet as they feed that's
because they're only interested in red
blood cells all the plasma gets
separated and excreted through their
skin amazing right now it's time to let
this little guy digest having a leech
attached to your skin is not really on
many people's bucket list but for
hundreds of years they've been used to
treat a huge range of
ailments in Europe and Asia leeches of
the genus herud medicinalis AKA
medicinal leeches are used to treat pain
inflammation and other health
issues in the wild these pretty ladies
feed mostly on ulates and other mammals
so they're happy to stick to human skin
they make an incision with their toothy
jaw and suck for about an
hour because of their powerful
anti-coagulants the wound often bleeds
for several hours
afterwards more recently beaches have
been used to help patients with limb
reattachment their anti coagulants
stimulate blood flow and accelerate
healing they've been especially useful
for finger
reattachments so thank you leeches your
blood sucking press is a testament to
the power of
evolution not all leeches are parasites
some are full-time predators and swallow
their prey whole of course their prey is
usually very small some other predatory
leeches don't swallow their prey but use
a probos to suck the bodily fluids out
of their prey a similar method to the
spiders or true bugs hunting strategy
some species in the glossop a day family
are escaro Specialists and only eat
snail bodily fluids they're also known
to be amazing parents carrying their
eggs in a pouch on their Underside when
they hatch the babies attached to their
parents sometimes sucking them dry all
leeches are hermaphrodites so any two
sexually mature Le leeches of the same
species can fertilize each other's eggs
which are then laid in a cocoon and in
this family's case they always win
parent of the
year the scariest leeches are probably
the ones that feed in mammal mucus
membranes the newly discovered tanoa Rex
named after the T-Rex because of its
relatively huge teeth is known to swim
up people's noses and feed there for
days to despite using them for Millennia
we're only starting to understand the
biodiversity of leeches there are likely
hundreds of species yet to be discovered
but I promise you if Sebastian discovers
another one you'll be the first to know
through this channel right
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here so what should we talk about next
please let me know in the comments and
be sure to subscribe for new episodes
every week thanks for watching and see
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you