[♪ INTRO] When you hear the word spider, you might immediately
think venomous, terrifying, or just... nope. Or you could be like me, and think they’re
amazing! Very few spiders are actually harmful
to people, while lots of spiders, pretty much all of them, in fact,
are helpful to us in some way. When you look at spiders more closely, you
realize they have some amazing abilities that may lead to really useful things like tougher
fabrics or stickier glues. So in honour of these eight-legged creatures, here are eight spiders that
push the limits of biology. Net casting spiders in the family Deinopidae
are sometimes called ogre-faced spiders because of their two huge forward-facing eyes. In one species, these eyes can reach 1.4 millimetres
in diameter. And while might not sound big, that’s the
largest eye relative to body size found in spiders, about a tenth the length of their entire body. It would be like you having eyes bigger than
cantaloupes. These eyes give the spiders a wide but shallow view of the world, kind of like looking through a fisheye lens. They also contain lots of light receptor cells,
allowing them to pick up around 2000 times more light than the eyes of day-dwelling spiders
or humans. But seeing that much light during the day
is problematic, so they actually destroy parts of their retinas every day and rebuild them
again just before nightfall. These special eyes are what allow net-casting
spiders to, well, cast nets. Though they technically build webs, they don’t
use them like other web-builders do. Instead of making a big mesh net for a bug
to run into, they spin a small web between their legs. Then, in the dark of night, they drop down
on their prey from above and envelop them with their sticky net. Scientists think the spiders’ net casting
hunting technique, along with those massive eyes, evolved during the Cretaceous period
as a way to get prey that could now run. And now, they’re inspiring sensor designs. Since the spiders’ eyes are so good at picking
out targets and detecting motion in low light, engineers are hoping understanding
how they work can help develop sensors that do better in complex, dark environments. Pelican spiders are pretty easy to identify
even if you’re not an arachnologist. That’s because attached to their weird ballooning
heads are two menacing claws which, at rest, look kind of like
the bill of a certain water bird. Now, all spiders have these mouth-related
appendages, called chelicerae. They’re the parts tipped with fangs. But pelican spiders have evolved the
longest chelicerae of any spider, and they use them to ruthlessly
hunt their 8-legged cousins. First, a pelican spider has to find and creep
up on its target. So, it uses its legs to feel for web trails,
the long strands of silk that spiders leave to find their way back to their web, or draglines,
the stronger, outer edges of the web. This stalking process can take several hours. Then, when a tasty spider is within arms reach,
the pelican spider juts out its chelicerae at a 90 degree angle, impaling its victim
and delivering a fatal dose of venom. And that’s not the most gruesome part. The pelican spider will usually just
leave their prey hanging there, struggling around, for half a minute
or so until the venom has done its job. Despite their unique look, not a lot was known
about these spiders until recently. In January 2018, a biologist from
the Smithsonian Museum described 26 species of this spider,
including 18 new ones. And that’s helping scientists figure out
how pelican spiders' unusual traits evolved and diversified over time. Darwin’s Bark Spiders spin webs that hold
not one, but two official Guinness World Records. They’ve got the largest webs because their
webs can be up to 2.8 metres across. And they’re the longest webs, too, because
their bridge lines, the tough strands which form the basis of the webs,
can be up to 25 metres long. Such uniquely big webs are
thanks to a special silk that’s the perfect combination of
strength and stretchiness. All spiders make the structural part of their
web from what’s called dragline silk, which has a protein core covered with a thin
sugary protein layer and a fatty outer coating. But the dragline silk from a Darwin’s Bark
Spider is two times more elastic than other spider silks and 10 times stronger than Kevlar. And that allows them to spin webs where other
spiders can’t: across rivers. Their oversized cobwebs span
waterways and grant them access to a bunch of flying insects
that other spiders can’t reach. And because of the strength of their webs,
they can even catch small vertebrates. Their super strong and stretchy silk may even
save human lives one day. Scientists are currently trying to figure
out exactly how the spiders make it in the hopes of creating a synthetic version, which
could lead to better bullet proof vests or other high-performance materials. The Mygalomorphae infraorder of spiders, which
includes tarantulas and trapdoor spiders, may have found the secret to a long life:
stay indoors and never change. Other spiders rarely make it more than a few years. But tarantulas can make it into their 20s, and Number
16, an unceremoniously named trapdoor spider, made it to the ripe old age of 43
before she died in October of 2016. Scientists think they live so long
because they spend their lives in stillness and solitude in underground burrows. Trapdoor spiders even seal themselves in with a
well-camouflaged door made of a cork-like material. And that means, a lot of the time, they just
kind of hang out in their home while they wait for a meal to come along. Staying in keeps them safe from most predators
and other threats, like dehydration. Their restful hunting style also means they
need to have a low resting metabolic rate. Their basic cellular workings need to be pretty
energy-efficient so they don’t burn through all of their fuel reserves before they can
stock up again. And there’s a theory that a low resting
metabolic rate means a longer life because using up energy creates damaging molecules called free radicals, so less energy use overall means
less damage to cells over time. Biologists don’t think that that’s the
whole story to their longevity, though. They’re still figuring out how metabolic rate,
free radicals, body size and aging all fit together. And that information could help them unlock
the secrets to longevity in people, too. This next spider takes prey capture to a whole
new level of weird. The spider family Scytodidae spit to immobilize
their meals. Most spiders make silk in glands at the rear
of their abdomens. But, when their prey is 2 centimeters or less
away, a spitting spider unleashes a spray of liquid silk from the
venom glands in its chelicerae. The spit is forced out thanks to a buildup
of pressure that comes from having large venom glands and a tiny muscle at the base of those
glands that squeezes when it’s time to fire. While spitting, the spider wiggles its chelicerae
from side to side at a rate of 1700 times a second
to spray a zig-zag pattern. And the silk becomes sticky when it comes
in contact with the air, pinning the prey down. This whole spit attack happens in
one seven-hundredth of a second. The spider can even regulate how much spit
it sprays depending on the prey’s size and how much its likely to struggle. Once its meal is firmly glued down, it will
sidle up and inject its prey with venom to fully immobilize it before actually eating
its meal. Scientists are still debating about whether
that initial spit contains venom that immobilizes the prey or if it’s just a kind of glue. On the one hand, the spit is made in venom
glands which have the ability to make both venom and sticky silk. But prey don’t look like poisoned when they
get shot, so the glands could be making silk
and venom at different times. And research to settle this debate isn’t
just to prove who’s right. Figuring out what’s actually in their sticky spray
could help engineers develop better adhesives. As you’ve probably heard before, brain size
isn't everything when it comes to intelligence. That’s particularly true for the fringed
jumping spider, a spider with a brain the size of a sesame seed that plans and fine
tunes its strategy with every hunt. They’re found in parts of Australia and
Southeast Asia, and they have to use their smarts
to catch their prey, other spiders. They use what’s called aggressive mimicry,
kind of a wolf in sheep’s clothing approach. A fringed jumping spider might pluck the edge
of a spider’s web to create the exact same vibrations as a caught insect, for example. Or, it might hide itself in a leaf and vibrate
its body to mimic other species’ courtship displays. And which approach it takes doesn’t come
down to chance. The spiders can plan ahead
and change their strategy if an approach doesn’t work
the first time around. Scientists have shown their smarts in the lab too. These spiders can navigate and plan
routes through mazes, and they can find their way to a tasty snack after
only seeing the path briefly. They’ve also been known to use trial and
error to escape from a platform surrounded by water, rather than just using the same,
failing method each time. Some scientists think they developed such
smarts as a part of an evolutionary arms race between them and the spiders they eat. But the piece of the puzzle that’s missing is an
understanding of just how these clever spiders are able to do the things they can. Researchers are now studying their teeny brains in the hopes of learning more about
the neural basis for intelligence. Ponds and streams contain a lot of potential prey, if a spider if is willing to get their feet,
or rather their whole body, wet. And that’s why some spider species will
venture into the water on occasion, but there’s only one that lives almost exclusively underwater:
the diving bell spider. They can be found in slow moving streams, ponds
and swamps from Europe through central Asia. And they spend almost all of their lives below the surface, even though they can’t actually breathe water. Instead, they spin a special web between underwater
plants with three different types of silk fibers, and then drag air from the surface
to fill the space underneath it. Diving bells do all sorts of things in their
web-bubbles. They eat, sleep, and mate. And when they’re hungry, they can actually
swim around for a little bit in search of prey thanks to the fine, water repellent hairs
on their bodies. These hairs hold onto a little bit of air,
which acts like a scuba tank of sorts. You see, spiders breathe through small holes called spiracles on the underside of their
abdomens that connect to their lungs. As long as these holes are covered with air,
they can breathe, even if the rest of their body is submerged. And diving bells can tolerate lower levels
of oxygen than their kin, so they can swim out of their bubble homes
to grab a quick bite to eat without drowning. In fact, they’d probably live their entire
lives underwater, except the bubbles in their webs slowly shrink. So, once a day or so, they have to surface
and bring down a few batches of fresh air. And understanding how they create their little
bubble homes could lead to better materials for underwater use. Scientists are hoping analyzing the structure
of the different threads they use can help us make things that
stay glued when they get wet. You might have seen this last spider lurking
around your home, but you probably didn’t know it was
also an official world record holder. The giant house spider held the Guinness World
Record for fastest spider until 1987 when it was replaced by members of the arachnid
order Solifugae, and those aren’t true spiders, so I think it should have kept its title. Giant house spiders can run as fast as half
a meter per second, or 1.8 kilometers per hour. Which, OK, means it’s only about a tenth
as fast you are, but proportional to its size, that’s the same as you running 55 meters
a second. Giant house spiders run by alternating the
movement of their pairs of legs, two pairs stay on the ground and support
the body while the other two move forward. And their super fast speed largely comes from
having really long legs. Their leg span can reach as much as 10 centimeters. They likely developed such speed because they
don’t rely on sticky webs. Like other funnel-web spiders, giant house
spider webs are relatively flat with a funnel at one end that the spider hides in. And they aren’t sticky, so they just trip
things up a bit, and send vibrations to the spider
that alert them to a potential meal. The spiders then rush out to attack, using
venom to subdue their prey. Before you get too worried: that venom, while
deadly to bugs, is basically harmless to people. And try to keep in mind: if you see one of
these spiders running, it’s probably running away from you. In their eyes, you’re the scary creature. Since their legs are so important
for running to catch their food, house spiders can actually regrow them
if they get chopped off. And studying how they do that
could help us figure out how to grow our own organs or
limbs in the lab one day. Whether it’s building bridges across rivers
or solving puzzles, spiders are so much more than just annoying or spooky
creatures on the ceiling of your room. Many have smart or elaborate features that
allow them to do some pretty extraordinary things like spend a day underwater or destroy
and regrow their retinas. And by studying them, we might just learn
a few new tricks, too. Thanks for watching! If you liked this
episode on incredible arachnid abilities, you might like our list of 7 unbelievably hardcore ants. [♪ OUTRO]
