The Shape of Things
Sea shells, Crystals, Honeycombs, Eggs and seeds: They are shaped the way they are for a reason. NOVA takes viewers on a unique journey of discovery to find out why things are shaped the way they are and why they work so well.
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00:00Our world is made up of a variety of shapes.
00:12Often their beauty is the outward appearance of an underlying structure.
00:17What forces determine the shape of our natural world?
00:23This will be a journey amidst nature's diversity
00:27to discover a small vocabulary of forms
00:31that reveal the secret behind the shape of things.
00:52Nature is a Kaleidoscope of Shapes
01:23Some are made by animals like insects.
01:27Some are the growth forms of plants.
01:30And some, the patterns of crystals.
01:37The same basic shapes appear again and again.
01:41Is it coincidence?
01:43Or is it because each of these shapes works in some unique way?
01:53What do things that resemble each other really have in common?
01:58And how do they get their shapes?
02:07This will be a journey of discovery through familiar natural surroundings,
02:11beneath the surface of things,
02:13and into the way different forms are made.
02:18It isn't always obvious,
02:20but there may be a pattern in the way a river bends,
02:23and in the way trees are spaced in a forest,
02:26and in the way lilies grow in a pond.
02:30Whatever the process may be that leads to form,
02:33one thing seems clear.
02:35Natural things produce many variations on a few basic themes,
02:40for nature is a maker of shapes.
02:45At the submicroscopic level,
02:48there is an underlying order in the chemistry of the formation of these crystals.
02:55They have a rigid substructure
02:57determined by the way their atoms and molecules fit together.
03:03They have a rigid structure determined by the way their atoms and molecules fit together.
03:09Just as the shapes of these crystals echo their internal structure,
03:13the shape of any natural thing depends on its composition
03:17and the forces acting upon it.
03:21The forms described by geometry and mathematics
03:24are not just abstract ideas.
03:28The sphere,
03:31the polygon,
03:34the sphere,
03:37the polygon,
03:40the spiral,
03:43the helix,
03:46the meander,
03:48and the branch
03:50are familiar throughout nature.
03:53Shapes like these are the signposts of order
03:57amid nature's abundant variety.
04:03Even within a drop of water,
04:05there is a teeming diversity of life.
04:09Microscopic living things
04:11inhabit a world as rich and varied as our own.
04:21These are spherical colonies of individual algae called volvox.
04:26The sphere is a common shape for very small organisms that live in water.
04:32Seen with a standard microscope,
04:34the skeleton of this marine creature is barely discernible.
04:38But magnifying it thousands of times
04:41shows that it's not only a sphere,
04:43but that it's a complex structure made of many parts.
04:51This dome is only one of the hundreds of individual lenses
04:55in the eye of a horsefly.
04:57These tiny hemispheres have grown together
05:00in a pattern of repeating units
05:02covering nearly all of the fly's head.
05:06This remarkable compound eye
05:08lets the insect see in many directions at once.
05:14Polygons, including triangles and hexagons,
05:17are the basic structural unit
05:20in the skeleton of this tiny marine organism.
05:24These shapes are formed by intersecting struts of glass-like silica.
05:32On a far larger scale, but extraordinarily similar in structure,
05:36the skeleton of this glass sponge is several inches long.
05:47This spiral shell is only a tiny fraction of an inch across.
05:52The shells of many mollusks throughout the world have a similar shape.
05:58They build their protective armor with near mathematical precision,
06:02creating the ever-expanding curve of the spiral.
06:07Some spirals make many turns,
06:09and some, like this argonaut egg case, make only one.
06:26The tendril of this vine grows in the form of a helix.
06:32It developed these coils so that it could contract like a spring
06:36as a way of getting closer to a support structure.
06:41And the movement of these vines around a pole also creates a helix.
06:51The meander is a regular repeating curve
06:54that rivers form as they flow across the landscape.
06:58And in a shape similar to flowing water,
07:01a snake, too, moves in meanders across the ground.
07:08When a cabbage is sliced in half, the form that's revealed looks like a tree.
07:13This is only one example of the patterns made by branching systems.
07:20The feeding tentacles of a feather duster worm
07:23make a radiating pattern on the face of a coral reef.
07:30The eight tentacles of the octopus also make a radiating pattern.
07:40Living things do not necessarily keep the same shape.
07:44They often change as they grow.
07:53These salamander eggs are spherical at first.
07:59But when cells grow and specialize as different parts of the body develop,
08:04the shape of the embryo starts to change.
08:17The form it now begins to assume is a shape suited to its environment.
08:23It's molded by millions of years of evolutionary trial and error.
08:35The same is true of plants.
08:38Their designs have evolved as workable solutions
08:41to the problems of gathering light and air
08:44and drawing water and nutrients from the ground.
08:48There is often a relationship between natural forms,
08:52their functions, and the materials they are made of.
08:57Environmental factors like gravity, light, and the weather
09:01can play a part in the development of natural shapes.
09:06A change of season has a noticeable effect.
09:10Birds move south.
09:12Plants become dormant.
09:14And as it gets cold, the water in the pond and in the air
09:19undergoes a change of state, and with it, a change of shape and structure.
09:25Water vapor changes to frost on these seed pods.
09:32The pond freezes over,
09:34and an icy frost forms on the branches of this pine tree.
09:40These small plates clinging to the pine needles are individual ice crystals.
09:49When water freezes, sheets of crystals come together in a seemingly irregular pattern.
09:57But ice has an inner structure that begins at the molecular level.
10:04This represents a water molecule.
10:07The movement of the molecules is slowed down by the cold,
10:11so if they get close enough, they will bond to each other.
10:16The magnet-like attraction between them makes them fit together
10:20so that they form six-sided shapes, hexagons.
10:27The molecules fit into the assembly like the pieces of a puzzle.
10:39These molecules are a small part of a piece of ice.
10:46The structure they make is known as a crystalline lattice,
10:50a three-dimensional grid based on the location of molecules
10:54that makes a repeating pattern throughout the ice.
11:01When water freezes and millions of molecules combine,
11:05the hexagonal geometry is still there.
11:10Now visible to the eye, it is a reflection of its own molecular substructure.
11:18This crystal formation is a process of growth
11:21in which water becomes a solid under the influence of cold weather.
11:27The ice on the surface of this pond has the same crystalline structure as frost.
11:33The texture and clarity of ice are determined by subtle variations
11:37in factors like sunlight, air temperature, and humidity.
11:49When turbulent winter storm clouds gather and the temperature begins to drop,
11:54the water vapor in the clouds freezes, forming small particles of ice that fall as snow.
12:10From winter blizzards comes one of the most delicate and beautiful
12:14of all natural structures, the snowflake.
12:18The snowflake is an ice crystal that forms the same way as the ice in frost
12:23or on the surface of the pond.
12:26Snowflakes come in many shapes, but if the structure of ice is always the same,
12:31how can there be such variety in snow?
12:37A snowflake is born when the moisture in a cloud forms as ice,
12:42often around tiny particles in the air like dust or salt.
12:51True to the hexagonal geometry of its molecular lattice, the disk grows into a hexagon.
13:02More ice forms at the six radiating points.
13:11Variation in conditions of the immediate surroundings lead to variation in shape.
13:19A branching pattern like this is most common when it's around 6 degrees Fahrenheit in the cloud.
13:26But even so, it is unlikely that any two snowflakes are alike
13:31because no two snowflakes form under absolutely identical conditions.
13:40When the humidity in the cloud is low, more plate-like hexagons like these tend to form.
13:52And the more ornate ones form only in a narrow temperature range and with higher humidity.
14:09As different as they may be, ice and trees both create branching patterns.
14:15The patterns come from the way the environment affects the materials they're made of
14:20and the way they grow.
14:23Entirely different influences may govern the growth of ice and plants,
14:28but they often end up with similar forms,
14:31such as the radiating spikes on these seed pods and on Queen Anne's lace.
14:37Even though natural objects are made of different materials, they can have related forms.
14:46And a single material can assume different structures under different circumstances.
14:52When water is frozen, it becomes ice.
14:58When subjected to weather conditions, water makes other shapes.
15:10Running water is given no constant form by its internal structure.
15:16When it flows, it follows the contour of the stream's bottom and banks.
15:22It takes its shape from the conditions around it.
15:27The water pours smoothly over the fall.
15:37The turbulence below tosses water into the air.
15:41The water separates into a fine spray of many drops.
15:45The smallest ones are almost perfect spheres.
15:53We know that water forms drops, but why should drops form spheres?
16:00The surface of the water acts like a thin elastic film.
16:05When this drop hits the water's surface, a small crater forms.
16:10When the water rebounds to fill the crater, it surges upward, making a column.
16:17A bulb of water forms at the top of the column with a narrow neck below it.
16:22Its momentum carries it upward while the rest of the small column falls back and a drop breaks free.
16:30The film on the surface of the drop contracts,
16:33forcing its contents into the most compact shape that fluid can form, the sphere.
16:43The surface film that makes a sphere of a drop of water
16:46acts like the film of soap that makes a sphere of a soap bubble.
16:59This bubble is a skin of water and soap stretched around a volume of air.
17:04The air is as formless as the water, so the film around it tightens
17:08until it has packaged the air as compactly as possible.
17:14A sphere uses the least amount of surface material to enclose a given volume.
17:22Drops so small that their own weight doesn't distort them become perfect spheres.
17:28This drop is too large for surface tension to draw it into a sphere.
17:33But because of its relative strength, the surface film can be an impenetrable barrier
17:38to very small creatures like this copepod.
17:49Many living things, such as fruit like cherries and crab apples, also resemble spheres.
18:01These fruits are not formed by the same process as water drops and soap bubbles.
18:09And it is often less clear what the relationship is between their form and their function,
18:14or what advantage there is in these shapes.
18:20But there is a definite advantage in the form of these mallard duck eggs.
18:24Their oval shape is curved, somewhat like a sphere,
18:28and their shells make strong and efficient packages for the embryo inside.
18:35This is the edge of an eggshell highly magnified.
18:39It's made of these bullet-shaped calcite crystals with rounded points at the lower ends.
18:48Eggshells are not as fragile as they seem.
18:51They are strong from the outside and weak only from the inside.
18:57Like the stones in an arch, the individual calcite crystals are packed tightly together.
19:05The shell is only 17 one-thousandths of an inch thick.
19:13When pressure is applied to the outside,
19:16the shell works like the arch in a bridge that carries the load to each side.
19:24And like the stones in a structural arch, the greater the pressure on the crystals, the tighter they get.
19:32The shell is strong enough to support the mother duck.
19:36It can also support two dozen aunts, uncles, and cousins, more than 50 pounds of ducks.
19:44The shell can withstand pressure from the outside.
19:47But a duckling, pushing from the inside, doesn't pack the crystals together.
19:52It forces them apart and the shell breaks.
19:57The eggshell works.
19:59It's a shape that protects its tenant and then yields when it's time for the duckling to emerge.
20:06Architects and engineers have discovered the strength and efficiency of these rounded shapes.
20:12They have been making domes for thousands of years
20:15and are still building variations on the basic theme illustrated by the egg,
20:20a very small surface area for a given volume, a light structure with a rigid shell.
20:35As water flows over this fall, it carries some air with it into the stream below.
20:42The air rises to the surface as bubbles.
20:46And when they are packed tightly together, they make a froth,
20:50an integrated system of rounded polygons forming partitions.
20:57Seen in two dimensions like this, the partitions join three at a time.
21:02Here's one three-way joint.
21:04Here's another.
21:06Here's another.
21:09Here's another.
21:11They enclose a six-sided figure.
21:13It's hexagonal, as are most of the bubbles on the surface of this froth.
21:18It's shaped like an ice crystal, but it doesn't come from freezing.
21:22It comes from the physical pressure of bubbles crowding together.
21:27Single bubbles made like this start as hemispheres.
21:39When the two of them touch, they form a common wall.
21:44A third one makes a shared three-way partition.
21:48Resting on the surface of the water like this,
21:51there will never be more than three around a single joint.
21:57Each bubble keeps its original amount of air,
22:00but partitions are shared so less surface area is needed to enclose the same amount of air.
22:09Partitioning
22:16Efficient systems of partitions are used to advantage by living things, too.
22:21Wasps and bees build nests with hexagonal cells.
22:28Less material means less work,
22:31less investment of energy per cell,
22:34and more cells in which to lay eggs.
22:39Veins
22:42The network of veins in this leaf uses three-way joints,
22:46meaning relatively short distances for the fluid to travel.
22:50And this common, freshwater algae is a web of individual cells joined three at a time.
23:01The hull of a rowing skull barely disturbs the calm surface of the water.
23:09But the turbulence caused by the oars makes another basic shape.
23:14When an oar pushes against the water, it makes a spiral whirlpool,
23:19a column of water spinning faster in the center than the outside.
23:24It's the difference in the speed of growth which shapes this ram's horn,
23:28but in this case it grows faster on the outside of the curve and is forced into a spiral.
23:35The shell of this ordinary pond snail grows in a spiral,
23:39as does the shell of the chambered nautilus.
23:43It belongs to a group of mollusks that have inhabited tropical oceans
23:48for hundreds of millions of years.
23:51The chambered nautilus moves by jet propulsion
23:55like its distant relatives the octopus and the squid.
24:00The shell of the nautilus is a spiral of mathematical precision.
24:05The process of growth that generates this form is elegantly recorded in its interior structure.
24:12It may live for 20 years, though it's not certain how often it makes chambers.
24:18Each one is about 6% larger than the one before it,
24:22but they are all the same shape.
24:25As the nautilus grows, it creates chambers by secreting calcium carbonate,
24:30which gradually accumulates.
24:33The nautilus is the mold for its own shell.
24:37As the animal grows, its shell grows with it.
24:45Spirals are also a common pattern of growth in plants.
24:50It's found in the way both leaves and flowers grow.
24:56Each division in the face of this sunflower
24:59is a single, very small blossom called a floret,
25:03and they pack together in an orderly array.
25:10They create a pattern of growth,
25:13spiraling out from the center.
25:16While the bud is still closed,
25:19almost microscopic florets grow out of the center one after the other.
25:31Although it appears as if the newer florets are added to the outer edge,
25:36they are not.
25:39Although it appears as if the newer florets are added to the outer edge,
25:44in fact they originate in the middle.
25:47As new ones grow in, they force the older ones to the outside.
25:54The florets all grow at the same rate,
25:57and as they grow, the spiral pattern grows with them.
26:02It might seem that the florets grow along a spiral track,
26:06but each one is forced out from the center in a straight line
26:10as the head of the flower gets bigger.
26:19The reason that the pattern is preserved
26:22is that though the florets are of different sizes,
26:25they all grow at the same rate.
26:28If they were growing at different speeds,
26:31the pattern would be distorted.
26:37All composite flowers, whether they are sunflowers,
26:40or daisies, or their relatives,
26:43have heads that are made of separate florets.
26:50Like the chambers of the nautilus,
26:53all the florets are the same shape, but of different sizes.
26:58The order of their growth makes the spiral pattern,
27:02just as the tight wrapping of a young fern,
27:05and the increasing size of the leaves on this succulent plant
27:09are ways of growth that make spirals.
27:23The ores of the rowing skull make another shape
27:26that is closely related to the two-dimensional,
27:29flat spiral seen on the surface of the water.
27:33The part of the whirlpool that reaches down into the water
27:37is a helix.
27:47The vortex is a three-dimensional structure
27:50that twists like the rows of scales on this pine cone.
27:57A pea vine climbs by wrapping itself around a pole,
28:01and in the process makes a helix.
28:05When the vine reaches out with its tendril
28:08and encounters a support, it encircles it,
28:11then modifies the winding motion to make helical coils,
28:15pulling itself closer to the pole.
28:19The uneven bonds between these pairs of molecule groups
28:23cause the layers to rotate slightly as they stack,
28:28making the double helix of the DNA molecule.
28:33The substance that transmits genetic information
28:36is called a helix,
28:38and this helical structure is called a polyhedron.
28:42The polyhedron of the DNA molecule,
28:46the substance that transmits genetic information in living things.
28:57Each coil is a backbone of sugar and phosphate molecules.
29:01The information-bearing nucleotides are protected within the coils.
29:12A single strand of human DNA, coiled like this,
29:16can be 50 million times longer than it is wide.
29:26The continuous coiling of the helix
29:28relates it to another form commonly found in nature,
29:32the meander.
29:35A river loops across the landscape
29:37according to a predictable pattern of smooth elliptical meanders,
29:41shapes created by the force of flowing water.
29:47These curves are made by the way the river erodes its own banks.
29:54The water flows faster on the outside of the bends,
29:57slower on the inside.
30:00A cross-section through the river shows the action of the water.
30:04Where it's faster, erosion is greater,
30:07so it's deeper on the outside of the bend to the left.
30:10Shallow and slower on the inside to the right,
30:13so sediment is deposited there.
30:17On the outside, erosion eats the land away.
30:20On the inside, land is built up.
30:24This makes the riverbed change course over time.
30:28Rivers seldom flow in a straight line
30:30for more than ten times their width.
30:33Instead, they automatically make patterns
30:36which approach uniform curvature.
30:40Water flowing across a car windshield will do the same thing,
30:44but for a different reason.
30:46When the speed and the volume of this water flow are reduced,
30:49it begins to oscillate as the flow becomes faster on one side than the other,
30:54creating a meander.
30:58Water flowing across a beach at low tide
31:00forms many meandering patterns.
31:05And so do the linear ridges in this glacier,
31:08slowly moving below Alaska's Mount McKinley.
31:19There is another group of growth patterns.
31:22It is in the way the branches grow from a tree.
31:25It's also in the way florets radiate from a clover blossom,
31:29and in the way networks of vessels grow in animals or in leaves.
31:35The branching system is best understood if it's seen from the beginning.
31:43When this sunflower seed senses the right combination of heat,
31:47moisture, and light, it germinates.
31:55When plants grow, they show the development of a simple branching system.
32:01First, the roots.
32:05The young plants are sensitive to the force of gravity.
32:09It guides them toward a vertical position.
32:14Their roots can find the way to water,
32:17and their leaves the direction of the sun.
32:20Sources of food and energy attract branches.
32:26Leaves develop an internal branching pattern for distributing nutrients.
32:35And groups of leaves form variations on branching patterns.
32:48Flowers make radiating patterns
32:51as they reach out to attract pollinating insects.
32:59As a plant gets bigger, it continues to do what it did as a seedling.
33:03It grows branches.
33:05A mature tree is a work of natural architecture and engineering.
33:10This tree has tens of thousands of leaves
33:13and must grow a massive armature of wood to support them.
33:17The leaves themselves have branching systems
33:19that collect the sun's energy
33:21and through photosynthesis produce food for the tree.
33:25Since the wooden structure must be strong enough to withstand the elements,
33:29trees have ways of branching that are ingenious solutions to structural problems.
33:37This is a black oak,
33:39and if you look up at the branches you'll see what we call a habit,
33:44the branching pattern of the tree.
33:47Some trees branch very low to the ground
33:49and the other ones will wait until they get up higher and branch.
33:52Branches must support their own weight as well as their leaves.
33:56Wood is heavy, so to lessen the stress on the tree,
33:59the less use, the better.
34:03This is a diagram of evenly spread leaves.
34:06There are many ways for the leaves to be joined to the trunk.
34:11An explosion pattern.
34:15A double explosion pattern.
34:20Bilateral symmetry.
34:23Branches made of forks or three-way joints.
34:28How do these four patterns work as models
34:30for some common hardwood trees like oaks or maples?
34:36In this explosion pattern,
34:38each leaf would have its own branch
34:40and the combined length of them all would be long.
34:43A lot of wood for a tree to support,
34:45so not economical as a tree design.
34:48But if these branches are the florets of a button bush flower,
34:52the scheme works pretty well.
34:56It presents a dense array of tiny flowers
34:59to attract pollinating insects.
35:07For clover, it's a way of attracting attention.
35:10For the seed case of the cocklebur,
35:12it's a way of deploying hundreds of clinging barbs.
35:15A double explosion pattern
35:17reduces the overall length of the branches.
35:20But still, a lot of heavy wood to be supported far from the trunk,
35:24especially if the limbs get overloaded with snow.
35:28But for wild parsnip,
35:30this design distributes small blossoms over a large area,
35:34possibly making them more noticeable to pollinating insects.
35:38Because of its small size,
35:40the scheme doesn't strain this plant,
35:42as it would a much larger tree.
35:45A close relative, Queen Anne's Lace,
35:47uses the same structure.
35:49The goat's beard flower makes an explosion pattern of seeds.
35:54Each seed has a secondary explosion pattern for a parachute.
36:00If the main branches are the florets of a button bush flower,
36:05If the main branches have the same number of minor branches
36:09evenly arranged on each side,
36:11the overall amount of wood is even less,
36:14a favorable savings in material
36:16and a branching pattern used on some trees.
36:21You can see it in the profile of many evergreen trees,
36:25in the organization of their individual branches,
36:28and in the way the needles grow from them.
36:32This fern is made of rows of minor branches.
36:36Each of these is made of rows of leaves,
36:40and each of these is made of rows of veins.
36:44The smaller parts of this fern are models of the whole.
36:55In this branching pattern,
36:57each limb is made of forks, linked three-way joints.
37:01The overall length of the branches is the lowest of all four models.
37:06This means the least weight to be carried
37:09and the shortest distance for fluid to travel
37:11from the roots to the leaves.
37:13A single limb on a maple tree is a series of three-way joints.
37:20A branching system using this pattern
37:24is common to many of the hardwood trees of North America.
37:29This tree grows in a pattern with the shortest root
37:32between the main trunk and each leaf,
37:35and it uses the least amount of wood.
37:38It's an economical structure,
37:40and it withstands both gravity and the climate.
37:45Like all things in nature, there is room for variety.
37:56Both the trunks and the branching systems of trees
37:59adapt to local circumstances and have their own individuality.
38:07The branching structure of a tree like this maple
38:10is dedicated to the support of leaves,
38:13and to the movement of fluid between them and the rest of the tree.
38:21Although wood seems solid,
38:23a microscopic view shows that it's actually made
38:26of thin partitions of cellulose.
38:32The fluid moves through these bundles of tubing.
38:36They form a substructure of polygons
38:39like the ones made by the bubbles in a froth.
38:48The walls of some of the tubing are reinforced against collapse
38:52with helixes one one-hundredth of a millimeter in diameter.
38:57As the stem grows,
38:59these coils can stretch without losing their strength.
39:05If a piece of oak is cut across the grain,
39:08it reveals a cross-section of the tubing in its circulatory system.
39:14As these vessels stiffen,
39:16they contribute to the support of the tree.
39:19Form and function is integrated.
39:22A single shape is both plumbing and structure.
39:27I'm going to give you each a leaf,
39:29and we're going to try what we call a leaf rubbing, okay?
39:32What I want you to do is put it underneath your paper
39:36and make it nice and flat,
39:39and then pick just one color crayon,
39:42the one that you like the best, here.
39:44You can finish your other pictures out.
39:47Thank you.
39:48Make sure that it gets nice and flat.
39:51A leaf is a microcosm of a tree.
39:54It has major veins radiating from the stem,
39:58and each one has tributaries leading to a lacy network
40:02dividing the surface into sections.
40:10These flat areas surrounded by veins
40:12contain the final destination of the fluid.
40:16Moisture, absorbed by the roots,
40:18is given off through these microscopic openings called stomata.
40:25It's the last stop in the branching structure of the tree.
40:31The large veins in a leaf are not only for the movement of fluids,
40:35they are structural as well,
40:37helping to stiffen and spread the leaf over the tree.
40:41The process of evolution responsible for the forms of branches,
40:45leaves, and wood
40:47has also helped to determine the designs of seeds.
40:51Maple and Ailanthus seeds, which are spread by the wind,
40:55have propeller-like blades.
40:58Sharp spikes keep animals out of these horse chestnuts
41:01before they ripen.
41:03These spikes are used to make the surface of the leaf flat,
41:07Sharp spikes keep animals out of these horse chestnuts before they ripen.
41:12And even though they're also toxic,
41:14squirrels will still collect and bury them,
41:17as they do with acorns and berries.
41:24Fruit and seeds are produced when flowers are pollinated.
41:29Flowers are the reproductive organs of plants.
41:34The individual florets in this sunflower open up.
41:38When insects come to gather the pollen,
41:41they fertilize the florets with pollen from another flower.
41:46Every fertilized floret
41:48becomes a seed containing an embryonic plant.
41:53The forms that seeds take
41:55are related to various strategies for distribution.
41:59One Ailanthus tree produces thousands of seeds a year.
42:06Each seed is a helix,
42:08an aerodynamic form twisted like a propeller
42:11that keeps it airborne for wide dispersal by the wind.
42:23Late in the summer,
42:25various lilies in this pond produce their extravagant blossoms.
42:32After pollination by insects,
42:34each one grows a cone-shaped pod with young seeds in the middle.
42:43When the seeds ripen, they become loose in the pod.
42:47Eventually it falls into the water and floats.
42:52It drifts upside down,
42:54and as it softens, the seeds fall out one by one.
43:05Like the seeds in the individual pods themselves,
43:08the cones pack against the shores of the pond by the thousands.
43:13As they are blown back and forth,
43:15they drop seeds all over the bottom
43:17where they will wait until next year
43:19or sometimes for many years before taking root.
43:24As the pod of the milkweed dries, it shrinks.
43:28The case splits and reveals a tight package of seeds inside.
43:36Each one is a tiny explosion pattern
43:39that makes a parachute so it will travel farther with the wind.
43:46The dispersal of some seeds depends on the warmth of spring.
43:50The seeds of the dogbane bush absorb moisture and heat,
43:54and the contents expand, splitting the seed case.
44:00Many plants distribute their seeds as widely as possible.
44:04This way a plant won't have to compete with its own offspring.
44:09Each of these seeds has its own parachute,
44:12and the wind does the rest.
44:16Living things are layers of patterns.
44:19A dandelion's seeds make an explosion pattern.
44:23The seeds were attached to an egg-like stub.
44:30It's divided by a spiraling pattern of cells
44:34meeting three at a time, making three-way joints.
44:40In the center of each cell,
44:42a tiny stalk that broke when the seed blew away.
44:52And on the head of the stalk, a grouping of smaller cells
44:56made with a tubing that once brought nutrients to the seed.
45:01And so it goes, patterns made of other patterns,
45:05repeatedly layered one upon the other.
45:13Behind the complexity of an organism like this plant,
45:17there are many basic shapes.
45:20Just as a plant can be seen as a composite of different forms,
45:24so can an animal.
45:27The antlers of the moose are huge branches,
45:30sometimes six feet across.
45:36The horns of an Alaskan doll ram are spirals.
45:41This kingsnake moves in a meandering pattern.
45:54And so does the moray eel of a Caribbean coral reef.
46:00This porcupinefish inflates itself into a sphere like a balloon.
46:07And the bony plates of the cowfish make a honeycomb of polygons.
46:12But these forms aren't always so easy to perceive.
46:19A bird is a bird of prey,
46:22a bird of prey is a bird of prey.
46:27A bird is a complex but highly organized system
46:31that depends on the integration of simpler forms
46:34to meet the demands of its way of life.
46:43Each of its feathers and the internal structure of its bones
46:47is based on fundamental patterns,
46:50just like its egg.
46:54These eggs are strong enough to take the weight of the mother duck.
46:59They are also made with an efficient use of material
47:02and minimized surface area reducing heat loss.
47:06While this mallard's young are in their eggs,
47:09patterns are developing that not only sustain life,
47:12but also anticipate the emerging adult form.
47:17Within days, cells specialize and coalesce
47:21into a nervous system and a spinal column.
47:24The living thing is beginning to take shape.
47:35Blood cells form,
47:37and with them the cells for veins and arteries.
47:47Together, they make a river of their own,
47:51like a tree, a limb, a leaf,
47:54a branching pattern for moving the raw materials for growth.
48:04It is the simplest way for all parts of a growing embryo to be nourished.
48:17This tiny heart drives a system of distribution,
48:20and a pattern emerges.
48:23At the center, the vessels are biggest,
48:26as they are in a leaf, the flow greatest.
48:30At the extremities, like the smallest veins in a leaf,
48:34the capillaries, reaching every single growing cell.
48:38The heart pumps the blood that connects the source of food in the yolk
48:42with the growing embryo.
48:47The system carries blood to the interface with the porous shell,
48:52where carbon dioxide is exchanged for oxygen.
49:00The yolk has all the raw material from which the embryo will construct itself.
49:05It has 28 days to grow all the systems it will need
49:09to break free and survive in the world outside.
49:17The shell breaks easily when pushed from the inside.
49:21Weak as it is, the duckling breaks out.
49:28It's an extraordinary process.
49:31The bird grew from a single spherical cell
49:34into a complex body that includes a beak,
49:37webbed feet, bones, and feathers.
49:40Each of these will soon toughen into the specialized features
49:44that suit ducks so well to their environment.
49:52Ducklings are able to swim within days of hatching,
49:56but they won't have the strength to fly for several weeks,
50:00for flight puts great demands on a bird's structural integrity.
50:06Fifty percent of the weight of a two-and-a-half-pound mallard
50:09is in its flight muscles,
50:11but its skeleton weighs only four ounces,
50:14barely ten percent of its total weight.
50:17A bird's skeleton must give maximum strength for minimum weight,
50:21or it could never fly.
50:23So its wing bones are hollow.
50:26Their walls are internally buttressed
50:29with a forest of rigid branching structures.
50:41A unique item of bird design is the feather.
50:45Hair, scales, plates, and shells can be found on many animals,
50:50but only birds have feathers.
50:55A feather is a branching structure.
50:59Each branch is zippered to its neighbor by smaller branches,
51:03making feathers air-resistant and self-mending,
51:07qualities essential for flight.
51:11Flight feathers are smooth,
51:14but some decorative feathers have a microscopic fringe on each branch.
51:20On this surface, much too small to see here,
51:23there is a regular grid that reflects light of only one wavelength.
51:30It's a submicroscopic structure that creates color
51:33like this brilliant iridescent green.
51:37These feathers grow on the heads and necks of male mallards.
51:41The duck's breast feathers and the down feathers beneath them
51:45make a warm and waterproof hull.
51:49Down is an excellent insulator
51:51because its branches are finer and farther apart
51:54than those of other feathers.
51:57These spaces make room for warm air next to the duck's body.
52:03In its simplicity, the feather has great versatility,
52:07a structure for warmth,
52:10a structure for color,
52:13and a structure for flight.
52:20The entire bird represents efficiency of form.
52:25It is streamlined to move smoothly through the air.
52:31With powerful muscles mounted on the lightest possible skeleton,
52:35it is the swiftest of animals.
52:38All aspects of bird design,
52:41its eggs, its skeleton, its feathers,
52:44combine in a whole that is greater than the sum of its parts.
52:49Throughout nature, basic shapes are shared by natural objects and organisms
52:54as diverse as feathers and trees,
52:57snails and sunflowers,
53:00honeycombs and snowflakes.
53:07Form comes from growth or from the way forces affect materials.
53:12Shapes are influenced by factors ranging in scale
53:15from the molecular to the environmental.
53:19The wind, the weather, and even the force of gravity
53:23are a few of the conditions imposed on shapes of all sizes.
53:34But these constraints are not limited to nature.
53:39But these constraints are not necessarily limitations.
53:43They are opportunities for new variations on old themes.
53:51Their beauty is the outward appearance of orderly structure.
53:58Basic shapes are only the beginning of the story.
54:01They lead to an understanding of structure in all living things
54:05because they are often the building blocks of more complex organisms.
54:13The need to conserve energy creates order.
54:16Disarray is wasteful of the materials and energy
54:19with which life confronts the environment.
54:25It is not always apparent why things are shaped the way they are,
54:29but nature is constantly creating similar forms
54:33over and over again.
54:39Within the diversity of nature there is order.
54:42And as the home of life, Earth is the planet of shapes.
55:03The Earth is the planet of shapes.
55:06The Earth is the planet of shapes.
55:09The Earth is the planet of shapes.
55:12The Earth is the planet of shapes.
55:15The Earth is the planet of shapes.
55:18The Earth is the planet of shapes.
55:21The Earth is the planet of shapes.
55:24The Earth is the planet of shapes.
55:27The Earth is the planet of shapes.
55:30The Earth is the planet of shapes.
55:33The Earth is the planet of shapes.
55:36The Earth is the planet of shapes.
55:39The Earth is the planet of shapes.
55:42The Earth is the planet of shapes.
55:45The Earth is the planet of shapes.
55:48The Earth is the planet of shapes.
55:51The Earth is the planet of shapes.
55:54The Earth is the planet of shapes.
55:57The Earth is the planet of shapes.
56:00The Earth is the planet of shapes.
56:03The Earth is the planet of shapes.
56:06The Earth is the planet of shapes.
56:18The material on this videocassette is protected by copyright.
56:22It is for private use only
56:24And any other use, including copying, reproducing, or performance in public, in whole or in part,
56:29is prohibited by law.