Living Things Change: Crash Course Kids #41.1 - Free Educational videos for Students in K-12

Living Things Change: Crash Course Kids #41.1 - By Crash Course Kids

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00:09	Hopefully by now you realize that our world is always
00:12	changing . Landforms change weather changes , even molecules change
00:17	with all of that change going on , living things
00:20	, I'd better be able to keep up and they
00:21	do when the world around them changes , living things
00:24	change too sometimes in a big way . So what
00:27	can happen to living things when the world around them
00:30	changes ? You may recall that once upon a time
00:37	we talked about pineapples and we said they were picky
00:40	because they could only grow in lovely , lush tropical
00:43	climates . No pineapples at the polls , right ?
00:46	That's because the environment in the tropics is perfect for
00:49	growing pineapples . An environment is made up of the
00:52	conditions around the living thing . Now that might sound
00:54	kind of like the definition of the word ecosystem ,
00:57	but the word environment is usually used to talk just
01:00	about non living things in an ecosystem like temperature or
01:03	the amount of rain or even how much pollution there
01:05	is . So while the environment at the polls isn't
01:07	great for growing pineapples , it suits other living things
01:10	just fine , like penguins in Antarctica and polar bears
01:13	at the North Pole , If we put these animals
01:15	into a pineapple field then get pretty hot and unhappy
01:18	, that's because they have adaptations for the cold .
01:20	An adaptation is a characteristic that helps an organism live
01:23	in its environment . But sometimes when environment changes ,
01:26	it upsets the delicate balance of the food chain .
01:29	In an ecosystem . For example , about 360 million
01:32	years ago , the earth looked a lot different than
01:35	it does . Now the earth was much warmer and
01:37	the land was covered with lots of forests and swamps
01:40	and the animals that live . Then let's talk about
01:42	Centipedes that were two m long amphibians over six m
01:46	long and Dragonflies that were the size of large birds
01:49	. Clearly none of these creatures are still around .
01:52	So what happened ? The environment changed over several million
01:56	years . The climate became drier and cooler and many
01:58	plants didn't have adaptations that help them to survive in
02:01	this new , cool dry environment . So they became
02:04	extinct . And that was a problem . Plants are
02:07	at the bottom of the food chain . They make
02:09	chemical energy through photosynthesis and they release oxygen . All
02:13	of those plants made lots and lots of oxygen .
02:16	There was more oxygen in the earth's atmosphere then than
02:19	there is now enough to support all of those giant
02:22	insects . But when the plants became extinct , the
02:24	animals that depended on all of that oxygen could no
02:27	longer survive . Chow , giant insects and the amphibians
02:30	and other animals that ate those insects had less food
02:32	. So they didn't do much better see a giant
02:35	amphibians . But let's take a look at how adaptations
02:37	can help a living thing fit into its environment using
02:40	another smaller insect . Mm . Meet the peppered moth
02:47	. Cute , right . And it comes in two
02:49	types light and dark as you can probably tell .
02:53	The dark colored moths are a lot easier to see
02:55	when they're resting on trees and easier to see means
02:58	more likely to become snacks for birds and other predators
03:00	. That means the light moths have an adaptation that
03:03	helps them live in their environment . So if we
03:05	went through the woods looking for moths , we would
03:07	expect to catch more dark moths than light ones .
03:10	Now what would happen if the environment changed ? It
03:13	did ? True story a couple 100 years ago people
03:16	started burning a lot of coal for fuel and this
03:18	made a lot of pollution . The pollution coated the
03:21	trees , turning them dark with soot and dirt .
03:24	The dark moths now had the adaptation that helps them
03:26	fit into the environment . They blended in with the
03:28	trees , which were now dark to the mosque that
03:31	were lighter though not so lucky in the polluted environment
03:34	, they couldn't blend in as well , so they
03:36	got eaten more often than the dark moths . The
03:38	dark moths that live reproduced to make more dark moths
03:41	. The results after the environment had been polluted for
03:44	a long time , there were more dark moths than
03:46	light one , fortunately we've gotten to be a lot
03:48	smarter about pollution over the last 50 years , the
03:51	environment has changed from more polluted to less polluted and
03:54	the trees aren't covered with dark dirt anymore . As
03:57	you can see in this diagram , the number of
03:59	light colored moths is on the rise . All living
04:05	things have characteristics that help them to fit into their
04:08	environment called adaptations . If the environment , the conditions
04:11	in which something lives changes , then the living things
04:14	change to the living things might gain different adaptations that
04:17	help them to survive in the new environment , or
04:20	the result might be more severe and affect the whole
04:23	food chain , but more on that next time .

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