- 6/9/2025
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TVTranscript
01:59One of the problems that faces us and all animals is finding enough to eat.
02:06Being animals and not plants, we can only feed on other living organisms, and by and large, other living organisms don't welcome that.
02:14Animals run away or defend themselves, and even plants have surprisingly effective ways of preventing anyone from robbing them of their leaves.
02:24Here I'm in the South American rainforest, the richest proliferation of life on Earth.
02:29So you might think that here, of all places, I'd have no difficulty in finding food, particularly if I was prepared to be a vegetarian.
02:37But it's not as simple as that.
02:39The woolly spider monkeys up there are taking their first meal of the day.
02:46It might seem to be a gentle, peaceful scene, but in fact it's a battleground.
02:51The tree defends itself by developing poison in its leaves, but when newly sprouted, they're just about edible.
02:58So the monkeys have to select which they eat with great care.
03:02Even with the greatest discrimination, they're bound to swallow a little poison, and now they've had as much as they can tolerate.
03:11They move off and find another kind of tree.
03:32This, too, has poison in its leaves, but it's a slightly different kind, so the monkeys can take a second course of their morning meal, providing they continue to be careful.
03:57There's another drawback to eating leaves.
03:59They're not really very nutritious, and the monkey has to eat great quantities to sustain itself.
04:06Huge meals require huge stomachs to hold them, and that means that the monkeys, to be honest, are not really the most nimble of movers up in the branches.
04:29And that means that the monkeys, to be honest, are not really the most nimble of movers, and that means that they take time off and have a siesta.
04:47Eating leaves is not easy.
04:49The small red panda of the Himalayas is one of the few animals that has beaten the defences of the bamboo.
05:06Its leaves are not only very fibrous, but armed with tiny blades of silica, so sharp that they can cut flesh.
05:13But the panda's digestion is able to cope with them, and the reward is that it has all the bamboo it can eat, since so few other animals will touch it.
05:22Bamboo also grows in Madagascar, and here the rare golden bamboo lemur feeds on it.
05:39It scissors through the coarse outer leaves on the stem to reach the marginally softer and more succulent ones within.
05:46Its preferred choice is not so much the leaves as the new shoots that come up through the ground like spears.
05:57They, of course, are particularly important to the plant, and it loads them with cyanide.
06:03Eating one of these uncooked could kill a man.
06:06The bamboo lemur can only eat them because its stomach produces special juices that neutralise the poison.
06:12But developing this ability has a price.
06:16The bamboo lemur now can't eat much else.
06:19So if the bamboo disappears, so does the lemur.
06:26The greatest plunderers of leaves, however, are insects.
06:31They're the most numerous creatures on earth, and a high proportion of them, either as caterpillars or adults, eat leaves.
06:38The evidence is everywhere.
06:42Insects are also fussy feeders.
06:50A female lays her eggs on the kind of plant her caterpillar's digestion can cope with,
06:55so when they hatch, they find the food they need immediately in front of them.
06:59They are little more than eating machines, a pair of jaws attached to a bag-like gut.
07:05No complications with wings and sex organs.
07:08Those will come later when they turn into adults.
07:10Now it's just munch, munch, munch.
07:14Plague beetles have a special way of beating a plant's poison.
07:32Since it's costly to produce, many plants only keep small stocks of it, and deter grazers by rapidly deploying it to the point of attack.
07:40But plague beetles descend on a plant in such numbers that its poison must be shared between many, and each beetle only gets a tiny and tolerable amount.
07:51It's true that each one only gets a small meal, but as soon as the plague has finished with this plant, it moves on to another.
08:06The milkweed invests much more in its defences.
08:18Its abundant and very poisonous sap, latex, is piped along special veins and is immediately available everywhere.
08:26But this beetle has worked out how to deal with that.
08:32It punctures the pipeline running along the leaf rib so that the milky latex leaks out.
08:38As a result, the poison never reaches the end of the leaf, and there the beetle can feed in safety.
08:53The latex also seals a plant's wounds, because it rapidly solidifies in air.
09:02But since it can't reach here, the beetle doesn't have any problem with gummed-up jaws.
09:11Marmosets also deliberately wound plants.
09:15They repeatedly gouge grooves in the trunks of trees that, when damaged, exude resin.
09:21Like the milkweed's latex, resin seals off the tree's injuries, preventing loss of sap and the entry of infections.
09:32But unlike latex, it's not poisonous.
09:35On the contrary, it's full of sugars and rather good to eat.
09:42And the marmosets love it.
09:44So the tree's measures to defend itself have actually resulted in encouraging its injury.
09:51But it's one of those that we should stop whilst the ratsum пс dudas.
10:12Not all plants are so uncooperative.
10:16Some actually encourage animals to come and feed from them
10:20and advertise the fact that they've got food available
10:23with brilliant displays, as these poppies are doing.
10:26This is not, of course, generosity on their part,
10:29but straightforward self-interest.
10:31The food they have to offer is a bribe
10:34to persuade the animals to act as couriers.
10:39They need to have their pollen ferried across to other flowers.
10:44Pollen, in itself, is edible,
10:46and bumblebees have a great taste for it.
10:54The bees have a complex arrangement of combs and brushes
10:57on their hind legs, with which they gather the pollen
11:00and pack it into baskets on their thighs.
11:09As they move from flower to flower,
11:11so some of the pollen that brushes onto their hairy bodies
11:15on one flower, brushes off on another,
11:18and the plant's purpose is accomplished.
11:27Pollen, packed with genetic material,
11:30is a complex and expensive commodity,
11:32and many flowers offer a much cheaper bribe,
11:35nothing more than sweetened water.
11:39Nectar.
11:41The plant produces it from nectaries
11:43that are usually placed deep in the heart of the flower,
11:46so that thirsty insects, to reach it,
11:48have to brush past the stamens,
11:50collecting a dusting of pollen on the way.
11:52In temperate lands, flowers can only be found in the spring and summer,
12:02when there's no frost.
12:04So insects that shelter from the winter, in nests,
12:07have to build up stocks as quickly as they can.
12:09They have, in fact, to be as busy as bees.
12:12In the tropics, on the other hand,
12:14there are always plants of one kind or another in bloom,
12:16so it's possible to feed on nectar throughout the year,
12:18and many animals do.
12:19This vine, Cumbretum, is particularly generous.
12:21Almost any animal that wants nectar
12:23can get it without difficulty when the plant is in flower.
12:25Many birds, which feed mostly on fruit, berries or even insects,
12:27come to drink from it.
12:36And so do monkeys.
12:50The smaller kinds, squirrel monkeys, tamarinds and marmosets,
12:53can clamber right out the ground to the nest.
12:56can clamber right out onto the thinner branches.
13:19Even the much bigger, hefty capuchins,
13:22which feed on fruit, nestling birds, lizards,
13:25and even on occasion small monkeys enjoy a sweet drink.
13:49As all the monkeys feed,
13:51so the stamens brush the fur on their face
13:54and the pollen is on its way to another flower.
14:03Nectar feeding has its problems.
14:05A Heliconia flower, like this one,
14:07produces only a little nectar at a time.
14:10So if a hummingbird comes to feed from one of these blossoms,
14:13it has to go elsewhere to get more,
14:16so bringing about the Heliconia plant's purpose of cross-pollination.
14:20And it takes a little time for the Heliconia to produce more nectar.
14:25So if the hummingbird comes back too soon,
14:27it may have wasted its journey.
14:29And if it comes back too late,
14:30some other bird may have stolen the nectar.
14:33As a consequence,
14:35hummingbirds patrol a whole group of these plants,
14:38visiting each flower in strict rotation to an accurately timed schedule.
14:52And he was right on time.
14:54Hummingbirds are among the very few animals that live almost entirely on nectar.
15:09Small insects are their only other food.
15:12And they've developed special equipment to collect it.
15:15The wings have joints that enable the bird to beat them with a whirling motion,
15:20giving it perfect control in the air.
15:24So it can hover in front of the flower
15:26and insert its beak with absolute precision.
15:29The tongue is long and thread-like,
15:37and flicks in and out 13 times a second.
15:50But this specialisation means that hummingbirds can feed on almost nothing else.
15:55And that puts them in the plant's power.
15:57It may seem that this hummingbird is deciding for itself which flower it will drink from.
16:02But you could equally argue that the plant,
16:04by controlling the rate at which it produces nectar,
16:07is dictating the movements of the hummingbird.
16:13Many hummingbirds have a bill which, in its length and curvature,
16:17exactly matches the shape and dimensions of the particular flower on which they mostly feed.
16:22The violet sabre-wing's beak fits into the columnia flower
16:26as accurately as a dagger slipping into a scabbard.
16:34And the flower has stamens placed in precisely the position needed
16:38to put a dab of pollen on the bird's forehead.
16:41So the sabre-wing and columnia have become partners.
16:49This suits columnia because its pollen is not taken by hummingbirds
16:53feeding on other kinds of flowers and so wasted.
16:56And it suits a sabre-wing because, since no other bird has exactly this shape of bill,
17:01it has all the columnia nectar to itself.
17:11But not quite.
17:12The mountain gem hummer has other ideas.
17:15It's waiting for the flower's legal partner to leave.
17:25Its bill is far too short to reach the nectar in the way that the sabre-wing does.
17:29With a thrust from its wings, it tries to pierce the flower.
17:33This time it holds the flower with its feet.
17:52It's broken in.
17:54Calumnia has been burgled.
18:01Another thief, only too eager to take advantage of a flower.
18:07Indian langur monkeys.
18:12The flowers of the Flame of the Forest are protected from raiders
18:16by being placed at the ends of long, thorny twigs.
18:19So they're reserved for their particular pollinators, birds.
18:26But langurs find them very tempting.
18:29This, of course, is disastrous for the tree.
18:48Its complex, subtle mechanisms for getting its seeds fertilised,
18:52evolved over millions of years, are being chewed to pieces.
18:56Even the remotest flowers aren't safe,
19:09for the young babies, braving the thorns,
19:11can clamber right out onto the thinnest branches without them breaking.
19:17In the continuous struggle between animals and plants,
19:20this round has certainly been lost by the plant.
19:26In the lush forests of the tropics where flowers bloom throughout the year,
19:38animals that feed on nectar can always find a drink somewhere.
19:42But in other parts of the world,
19:44where perhaps the winters are bitterly cold,
19:47or here in the parched deserts of Australia,
19:49where flowers only bloom after brief rains,
19:52animals that rely on nectar have to have some way of storing it
19:56to last them through the hard times.
19:59These mulga trees produce nectar on which ants feed,
20:04and they have the most extraordinary larders.
20:07The galleries of their nests lie four feet or so below the surface of the ground.
20:23These golden globes hanging from the roof are their storage pots, full of honey.
20:29Each one is alive, an ant with an abdomen expanded to the size of a grape.
20:36The small dark flecks are the hard plates which protect the body of a normal-sized ant.
20:41It's the membrane between them that is stretched.
20:44These bloated individuals are almost totally inactive,
20:49so they consume very little of the honey that they hold.
20:54It is drunk by the busy workers,
20:56who, when there's little food to be found above ground,
20:59come down here and induce the honey pots to regurgitate it.
21:03The workers also tend the swollen bodies, keeping them well-groomed and clean.
21:22During the good times, the workers collect all the nectar they can
21:25and take it down to the larders to top up the colony's storage jars
21:30by feeding it to them, drop by drop.
21:53The people who've roamed these deserts for millennia,
21:57the aborigines have always valued these ants as one of their few sources of sugar,
22:02and they eat them just as they are.
22:08Mmm.
22:13Mmm.
22:15It's liquid, warm and marvellously sweet.
22:19A few weeks after flowering, many plants tempt animals with another food, fruit.
22:29They have another problem.
22:31Their seeds are formed and need to be distributed,
22:34and by wrapping them in sweet edible pulp,
22:37they recruit lots of animals to do the job.
22:39The trees dissuade animals from collecting the fruit before the seeds are fully developed,
22:52by not producing the sugars in it until the very last moment,
22:55so unripe fruit tastes bitter and is really not worth picking.
22:59To indicate when it is, the fruit often changes colour.
23:11Squirrel monkeys are primarily fruit eaters.
23:16They move about in large groups of up to 40 or so,
23:19and they have to wander over a great area in order to find all the fruit they need.
23:24Capuchins, on the other hand, live in small families,
23:30each with its own patch of forest, which they know very well.
23:33They eat all kinds of things,
23:35but if there's a fruiting tree in their territory, they'll know about it.
23:42So, although the squirrel monkeys are frightened of the bigger capuchins,
23:45they nonetheless follow them as they forage.
23:54There may be something here for a capuchin, a lizard maybe, but no fruit.
24:09So the squirrel monkey is not interested and must wait.
24:20The capuchin moves on.
24:24And the squirrel monkeys follow.
24:36As the capuchins get near the fruiting tree,
24:38the squirrel monkeys, perhaps smelling the fruit,
24:41scamper ahead to try and get to it first
24:43before the more powerful capuchins can reach it and drive them off.
24:47Now they must grab as much as they can, as quickly as they can.
25:03The capuchins arrive.
25:21It's time for these squirrel monkeys to go.
25:35And they take with them, inside their stomachs, the tree's seeds.
25:51They pass through the monkeys unharmed and then, some distance away,
25:53they're deposited with a convenient dollop of fertilizer.
25:59Seeds themselves, of course, are packed with nourishment.
26:05So plants enclose them in shells, which can be strong enough to defeat even a mangabe.
26:11Victory to the plant.
26:13But the chimp is so clever, it can crack them.
26:17Victory to the animal.
26:27Sharp teeth enable an agouti to chisel into the acorn of a tropical oak.
26:33In spite of the acorn's armour, it seems as though the oak has lost this contest.
26:41But not totally.
26:43The oak produces many more acorns than the agouti can eat immediately.
26:47Those that it can't, it carries away and buries for later.
26:51But an agouti's memory is not infallible.
27:04Occasionally, it'll forget about one of the acorns,
27:07which will then germinate and may grow into a new oak.
27:10And that will be a victory for the plant.
27:16Perhaps the most extraordinary of all tools for nut-eating
27:20is wielded by a strange Madagascan lemur, the aye-aye.
27:32First it gnaws a hole,
27:34and then it scoops out the contents with this long bony probe,
27:37which is, in fact, its finger,
27:39but one quite unlike the rest on its hand.
27:42This curious digit serves just as well for eating a grub.
27:50The aye-aye uses it to mash up the body hidden in its burrow,
27:54and then flicks out the puree.
27:56The spiny pocket mouse has a double problem.
28:05The seed it's gnawing is not only hard-shelled,
28:08but packed with poison.
28:10The mouse does nothing more than puncture the shell.
28:13It then tucks it into its cheek and carries it back to its burrow.
28:17The hole in the shell stimulates the seed to germinate,
28:23and the tender white shoot that leaves the protection of the shell
28:26is poison-free.
28:28The macaw has almost certainly the most powerful nutcracker of all.
28:43It can demolish even the most resistant of nuts.
28:47But many of the seeds macaws eat are also filled with poison.
28:51Yet this doesn't seem to upset them.
28:54How do they survive?
28:58Every day they make long journeys through the forest
29:02to dose themselves with a special antidote.
29:15Macaws usually fly in pairs.
29:18Only in such places as this do they assemble in flocks.
29:28They've come to collect their medicine.
29:37The regular presence of so many birds attracts eagles and other predators.
29:42So before the macaws come out of the trees to get it,
29:45they want to be sure that it's safe to do so.
29:47And they wait for one bird, braver than the rest of them,
29:51to make the first move.
29:55There it goes.
29:56And this is what they're after.
30:00Kaolin.
30:01The soil in this river bank is rich in it,
30:03and several kinds of parrots and macaws come here every day,
30:07from miles around, to take the treatment.
30:10Kaolin combats acidity in the stomach,
30:20absorbs and neutralizes poisons.
30:23And as a bonus, this clay is rich in calcium and sodium,
30:27which is lacking in diets that consist of fruit and nuts.
30:30So, eating plants, posing as plants,
30:59poses more problems than one might think.
31:02But eating other animals, even small defenceless ones,
31:06also has its difficulties.
31:08It's dawn on the east coast of England.
31:12The middle of winter and food is very scarce.
31:16But behind me is a huge and abundantly stocked larder.
31:21Its doors have been shut for the past three hours,
31:24but now the tide is on the turn.
31:26And for a horde of hungry animals,
31:29their waiting is almost over.
31:33Tens of thousands of Knott and Dunlin
31:35have assembled on a lagoon on the other side of the sand dunes.
31:39They've sensed that the tide has exposed the mud bank.
31:54Breakfast is served.
31:55They've sensed that the tide has exposed the mud bank.
32:08Breakfast is served.
32:09Millions of tiny mollusks are buried just below the surface of this mud,
32:25and the birds are feeling for them with their bills.
32:28Abundant though the food is out there, collecting it is a very dangerous business.
32:43It's very exposed on the mud flats.
32:46There's nowhere to hide, nothing to dodge behind.
32:48And the birds deal with that problem by sticking together in tight flocks.
32:53That way each bird has a thousand eyes ready to spot danger.
32:58But if that is such a good idea, why is this redshank out on its own?
33:16It's hunting not by touch, but by sight.
33:23And it's searching for its favourite food, small shrimp-like crustaceans.
33:28If they're alarmed by ripples or vibrations produced by many moving feet,
33:33they will disappear into the mud where the redshank can't see them,
33:36and so can't find them.
33:41So if a redshank wants to catch this more swiftly moving food,
33:45it has to forage by itself, despite the risks.
33:54And if it does become a little alarmed, it just squats.
34:02But some waters are so rich in food, there's plenty for everybody.
34:06On this Indian lagoon, there are stalks, herons and egrets,
34:10openbills and spoonbills.
34:12Each has its own particular beak technique with which to catch its favoured prey,
34:17probing and sieving, scything and stabbing.
34:21,
34:22,
34:26,
34:28,
34:30,
34:31,
34:33,
34:39,
34:41,
34:42Even parts of the open sea, like this bay in the West Indies,
35:10at certain times, become so thick with fish that they can support great flocks of fishing.
35:32Barracuda, among the most ferocious hunters in the sea,
35:35and they regularly drive shoals of small fish into the bay.
35:40The End
35:42The End
35:44The End
35:46The End
35:50The End
35:52The pelicans can tackle the shoals even when they're a foot or two beneath the surface.
36:22But a pelican can only swallow the fish it's scooped up in its baggy bill if it lets the water drain out first.
36:47To do that, it must open its beak just slightly, and that is the moment the gulls are waiting for.
36:54A few places on land offer quite the density and richness of the sea.
37:01A few places on land offer quite the density and richness of animal food...
37:08...that can be found in parts of the sea such as this.
37:11But one kind of land animal does swarm in vast numbers...
37:15...and this little long-eared tenrec from Madagascar is in search of them.
37:52A few places they can carry along their pathways.
37:59Termites, the juicy, soft-bodied workers, are largely defenceless.
38:05But with them come soldiers.
38:08This kind squirt noxious chemical sprays for nozzles on their heads.
38:12The tenrec, with its sensitive nose, can tolerate a certain amount of chemical spray...
38:34...but after a while, it just has to come up for air.
39:04Termites are hugely abundant in the tropics...
39:07...and many different kinds of animals collect them when they get the chance.
39:18A small gecko, in the deserts of Australia, eats little else.
39:22The problem is those soldiers.
39:24But it's such a fastidious and accurate feeder, it can avoid them...
39:28...and pick out the defenceless workers one by one.
39:40Of all food collecting devices, the most ingenious and elegant...
39:44...must be the webs of orb spiders.
39:47It's nearly always the females who build them.
39:50One starts by rigging filaments of silk across a flyway used by insects.
40:11Around the spokes, using silk of a different kind, she sets a spiral mesh.
40:16As she secures each section, she twangs it...
40:21...so that the glue with which it's coated breaks up into a line of sticky beads.
40:33One of the biggest of these webs, which may be two yards or so across...
40:37...is constructed by the Nephila spider.
40:40She is huge.
40:45Her legs can span six inches, and she's virtually blind.
40:49A fly, blundering into her web, is quickly seized.
40:55She rapidly injects it with a venom that will liquefy the contents of its body.
41:01She then wraps it up in silk and parks it on the web to allow the venom to take its effect.
41:13Her Chinese
41:33But Nephila is not alone on her web.
41:37Argyrodes is tiny, much smaller even than the fly,
41:41and she could easily become a meal for Nephila.
41:44She too is blind,
41:46but she's also felt the vibrations of the struggling fly.
41:50With what seems like suicidal recklessness,
41:53she approaches Nephila, still feasting on her prey.
41:57And she too begins to eat food that Nephila not only caught,
42:08but has conveniently pre-digested.
42:13Another capture calls Nephila away.
42:24Once again, she stabs the fly,
42:26trusses it up, and carries it away
42:28to hang on the side of the web.
42:30She'll eat that later.
42:37Argyrodes seems well aware of what's going on.
42:50As soon as Nephila has finished hanging up her latest catch,
42:53Argyrodes starts trying to discover its precise position
42:57by pulling the web filaments.
43:15Nephila has returned to finish her first meal.
43:17Meanwhile, Argyrodes has run a line from the top of the web to the fly,
43:20which she's now cutting loose.
43:25Argyrodes has run a line from the top of the web to the fly,
43:26which she's now cutting loose.
43:27Argyrodes has run a line from the top of the web to the fly,
43:29which she's now cutting loose.
43:30Argyrodes has run a line from the top of the web to the fly,
43:31which she's now cutting loose.
43:32Argyrodes has run a line from the top,
43:39and she lifts up her bury together.
43:50It's pretty clear.
43:53Once the fly is free of the web, she lowers it down.
43:57Argyrodes will driest bit of a lump.
43:58The stolen fly is now hanging entirely free.
44:15Nephela won't be able to reclaim it now.
44:18Even so, Argyrodes must get it away to a place where she can feed on it in safety.
44:24Step by step, she heaves it up.
44:29Her theft is complete.
44:36Tropic birds nest on this cliff in Tobago in the West Indies.
44:40They are magnificent flyers, able to exploit all the currents of the air with spectacular ease.
44:47They fish out at sea, and every day the hard-working parents return to their nests
44:59with crops full of food for the family.
45:01Frigates in the 18th century were swift, heavily-armed warships which plundered merchantmen.
45:20And these are frigate birds.
45:26The fishing fleet is returning.
45:28The fishing-
46:18The frigate wasn't trying to kill a tropic bird,
46:28only to make it surrender its cargo of fish.
46:31But it'll have to find a less determined victim.
46:35The usual tactic of these pirates is to come up astern of the chosen victim
46:39and grab its leg or tail.
46:48It surrenders.
46:53There goes the disgorged fish and the frigate catches it.
46:56There goes the disgorged fish.
47:26The frigates aren't always successful.
47:46Watching them harrying the tropic birds,
47:48you can't help wondering if it wouldn't be easier to catch the fish directly for themselves.
47:52And indeed, they often do.
47:54But they seem positively to enjoy a life of piracy.
48:00As to the tropic birds, well, most of them escape.
48:03And even those that are caught only lose a few fish.
48:05But it's only a short step between robbing your victim and killing him
48:11for the pirate to become a hunter.
48:15And that raises a completely new set of problems.
48:18And it's those that we'll be looking at in the next programme.
48:21one, two, three, four.
48:37One, one.
48:37One, two, three.
48:40One, two, three.
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