Ancestral & Weird Senses: Crash Course Zoology #8 - Free Educational videos for Students in K-12 | Lumos Learning

Ancestral & Weird Senses: Crash Course Zoology #8 - Free Educational videos for Students in k-12


Ancestral & Weird Senses: Crash Course Zoology #8 - By CrashCourse



Transcript
00:0-1 before sight hearing or even touched before they were even
00:04 animals living things developed chemo sensation or the ability to
00:09 sense chemicals in the environment . And we know this
00:12 because every life form we've ever found has some form
00:16 of chemo sensation . But other animals have come up
00:19 with even more specialist ways to interpret information in their
00:23 environments with senses straight from the pages of comic books
00:27 . So in this episode we'll talk about the many
00:30 ways animals have made their ancestral chemo sensation their own
00:34 and how they've solved some of the challenges of following
00:37 your nose . But we'll also see electric colors with
00:40 an unusual african fish and follow pigeons trying to make
00:44 their way home with magnets glued to their backs .
00:47 I'm Ray Wynne Grant and this is crash course Psychology
00:53 . Yeah . Mhm . Mhm chemicals are pretty much
01:02 everything . Water , sugar , air all those liquids
01:06 , solids and gases around and inside of us are
01:10 chemicals and recognizing different chemicals is chemo sensation , which
01:15 today we know better as our senses of smell and
01:18 taste specifically . Key male sensation is the ability to
01:22 recognize a chemical based on the molecule shape and electric
01:26 charge . Only some chemicals can fit into the proteins
01:30 in the body called receptors in the right way and
01:33 not get repelled , which triggers signals getting sent to
01:36 the brain , which means chema sensation tells animals about
01:40 the world around them a little differently than sight and
01:43 hearing because it requires a physical interaction between the animal
01:48 and the molecules . It's sensing like taste happens either
01:52 when a chemical binds to receptors on our tongue or
01:55 when parts of those chemical molecules enter taste cells .
01:59 In both cases , the cells end up sending a
02:02 bunch of signals to the brain like sour for lemon
02:05 juice or sweet for candy smell . Also known as
02:09 olfaction works in the same basic ways taste smelly particles
02:14 bind to receptors , which also sets off signals from
02:18 our knows that our brain interprets as flowers or peppermint
02:21 or whatever . While animals usually have a few types
02:25 of taste buds , they have hundreds or thousands of
02:28 olfactory sensors . The big difference between taste and smell
02:33 is that taste happens when the thing we are tasting
02:35 directly contacts the receptors . Whereas smell happens when molecules
02:40 travel through a fluid like air into our smell organ
02:44 like a nose . We'll use a lot of smell
02:47 examples in this episode , but remember both taste and
02:51 smell are chemo sensation , they're related and in some
02:54 cases use the same organ like insect antennae that both
02:58 taste and smell . Under the right conditions , smells
03:02 travel way further than light or sound and are harder
03:05 to block with things like dense forest or rocks .
03:08 Chemo sensation is dependable , so animals deploy it for
03:11 a variety of important tasks like animals , you smell
03:15 to find things , especially food that they can't see
03:18 or hear because it's hidden behind something or too far
03:21 away . Like if you ask me , bears are
03:24 amazing and their sense of smell is one important factor
03:27 in their amazing nous . They're such good spellers that
03:31 we've never been able to truly test their limits ,
03:33 but they can sniff out food like beer larvae and
03:37 seals from miles and miles away . So with the
03:41 right nose , smell can be a super long range
03:44 sense , which presents a new challenge because odors can
03:47 slip through the tiniest of openings , spread out and
03:51 be detected at very low levels , all of which
03:54 can make it really hard to tell where the smell
03:56 is actually coming from . Not to mention that the
03:59 one who dealt it might be long gone before the
04:02 next animal smelt it . So animals have evolved adaptations
04:06 to track where a smell is coming from . The
04:09 evolutionary solution is to have chemo sensation organs that provide
04:13 information about direction , especially in pairs to better pinpoint
04:17 the smell . It's so useful to have paired smelling
04:21 structures . They've evolved over and over again . In
04:24 another example of convergent evolution , there are paired nostrils
04:29 paired in 10 A . That can move to pinpoint
04:31 smells and sounds fan like peck teens and scorpions ,
04:36 forked tongues and reptiles like snakes and much more .
04:40 Many of these tracking adaptations also help animals more generally
04:44 explore their environment . Animals also incorporate smell into special
04:49 behaviors to communicate like to attract potential mates or scare
04:53 away rivals . Like moths and orchid bees will climb
04:56 up high in trees to make sure they're attractive scent
04:59 carries far in the wind . And some animals leave
05:02 pee scat and other smelly marks and well traveled places
05:07 that are like a short biography how healthy they are
05:10 if they're stressed and if they're looking for a mate
05:13 . But it's not just pee or scat that animals
05:16 are sniffing . A lot of animals release pheromones chemicals
05:20 secreted by one animal to influence the behavior or physiology
05:24 of another animal . Some pheromones act as alarm cues
05:28 , warning other animals away from dangers . Others attract
05:33 or guide friendly animals down a safe path . Some
05:36 Mark territories and others influence animal physiology and behavior like
05:41 pheromones that cause egg laying or mating behaviors . Pheromones
05:45 can even be used by predators like the bolas spider
05:48 who uses pheromones to lay a trap for their mouth
05:51 . Pray chemo sensation is the O . G .
05:54 Sense and it's become incredibly useful for animals tracking ,
05:58 exploring and communicating . But some animals have additional senses
06:02 that basically make them real life superheroes like electro reception
06:08 which is being able to sense the electric fields or
06:11 currents that are pretty much everywhere in nature . In
06:14 fact , every time we use our nervous system ,
06:17 we're sending electrical signals through our body . So if
06:20 an animal can pick up on those tiny signals ,
06:23 they can sense other animals when it's hard to see
06:26 smell or hear them like in murky water . Plus
06:30 the earth's atmosphere has electricity in it too . So
06:34 electro reception can also tell animals about their environment .
06:37 Besides seeing the occasional spark or lightning strike , we
06:41 humans can't see or sense electricity . Almost all electric
06:46 sensing animals like duck billed platypuses , starters , moles
06:50 , sharks , and a lot of fish who have
06:52 this ability live in water because water conducts electricity much
06:57 better than air or Earth though , we've only really
07:00 looked for electro receptive animals with invertebrates . But starting
07:04 in the 1960s , scientists have been learning that several
07:08 arthropods react to electric fields , so electro reception is
07:12 a lot more common than we once thought . Some
07:14 electrically inclined animals go even further evolving special organs to
07:20 make their own electrical signals and actively sending them out
07:24 into the world around them . Either to find prey
07:27 or to chit chat with other electric fish . Less
07:30 experience a day in the life of one of them
07:33 . The elephant nose fish allow me to introduce the
07:37 peters , elephant nose fish of the dark and murky
07:41 waters of the rivers of West and central africa .
07:45 Her beautiful long schnoz isn't a nose at all ,
07:49 but an elongated chin covered in electricity sensing cells .
07:54 Each day she swims around , looking for snacks on
07:57 the riverbed and waving her chin around like a metal
08:01 detector on the beach and her electric organ , which
08:04 is made out especially adapted cells in the tale ,
08:08 sends out weak electric signals every few seconds , creating
08:12 an electric field objects like worms and rocks affect the
08:17 electric field , which she senses with her chin and
08:20 tells her where they are so she can root them
08:23 out from the gravel . Like most electric fish .
08:26 Her zepce aren't powerful enough to stun prey or scare
08:30 off Attackers , but rather they helped her understand the
08:34 world . What she's doing is similar to what bats
08:38 do with sound and Niko location , which is why
08:41 it's called electro location . And it basically lets her
08:46 see with electricity . Even a version of color as
08:51 she's looking for worms , snacks . The electricity sensing
08:55 cells in her nose . Chin respond to two major
08:59 characteristics as they sense electricity , how strong the signal
09:04 is and what shape it takes , which is kind
09:07 of how the cones in our eyes sense wavelengths of
09:10 light . The fish is brain then combines these signals
09:14 in very specific ways , just like lots of brains
09:18 combined signals from different photo receptors to perceive a color
09:23 , which gives each object an electric color . Certain
09:27 categories of objects like other electric fish or pray always
09:32 have the same electric color . Imagine if your favorite
09:36 food always glowed bright yellow , have a nice day
09:41 magnetism or the force exerted by magnets as they repulse
09:45 or attract each other is another fundamental property that some
09:49 animals can sense with magneto reception or the ability to
09:53 detect a magnetic field , which is usually the Earth's
09:57 while a surprising number of animals can shock you or
10:00 at least use electricity . No known animals make their
10:04 own magnetic fields . So magneto reception is entirely a
10:08 passive sense but useful . The Earth is a big
10:13 place and lots of animals like birds and flying insects
10:16 travel long distances to find mates food or to escape
10:20 inclement weather . And they need some kind of compass
10:24 . Other animals , like mole rats and cave salamanders
10:27 live underground where they can't see the stars or the
10:30 sun to tell them which way is east or west
10:33 . And that's where magneto reception comes in . It's
10:36 like a global compass that works in complete darkness .
10:40 Magneto reception is most well studied in migrating birds like
10:44 homing pigeons . In the early 19 seventies , a
10:47 zoologist at Cornell named William Keaton , glued magnets to
10:52 the backs of pigeons and observed that pigeons released on
10:56 sunny days could find their way home , whereas those
10:59 released on cloudy days got lost . Later on ,
11:02 scientists would find that pigeons had two major systems for
11:06 sensing magnetic fields during the day . They could use
11:09 proteins called crypto chrome's in their eyes that responded to
11:13 blue light in such a way that they reacted to
11:16 magnetic fields . And at night clusters of iron in
11:20 their beaks would be drawn vaguely north , kind of
11:23 like how a compass works , if that sounds mysterious
11:27 . Well , it is exactly how magneto reception actually
11:32 works is still something scientists are trying to work out
11:36 . For example , a lot more animals have cryptogram
11:39 in their eyes than we thought even us . So
11:42 there are some senses that are older than animals and
11:45 some that were just discovering because animals are always exploring
11:49 their environments with light , sound chemicals and even electricity
11:53 or magnetic fields to pick up crucial information . And
11:58 even though there are many different animals out there ,
12:00 we all sense and learn about the world in very
12:03 similar ways . Med Isoa really is one big happy
12:07 family so far in this course , we focused mostly
12:11 on single animals on their own . But next episode
12:15 we'll get into what happens when animals get together to
12:18 pass down their genes . I'll see you then .
12:21 Thanks for watching this episode of Crash Course ideology ,
12:24 which was produced by complexity in partnership with PVS and
12:27 Nature . It's shot on the team Sandoval Pierre stage
12:30 and made with the help of all of these nice
12:32 people . If you'd like to help keep Crash Course
12:34 free for everyone forever , you can join our community
12:37 on Patreon . Yeah .
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