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Programme synopses
Life In The Undergrowth:
Invasion Of The Land
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Just over 400 million years ago, creatures left the sea to move on to land. They were the invertebrates.
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Since then, they have become the most successful group of animals, adapting to every environment on Earth. Now, for every human, there are 1.6 billion of them.
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Their largely unseen world is revealed as David Attenborough tells the story of the land living invertebrates.
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New technology means that cameras have been able to show invertebrates in extraordinary detail, revealing for the first time the courtship dances of tiny springtails and the way they can catapult themselves away from danger.
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These tiny creatures can be found on garden plants, in leaf litter and in gutters but, until now, their amazing acrobatic skills have gone unnoticed as some are only the size of a full stop.
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Another common garden resident is the leopard slug which has a truly bizarre end to its marathon mating ritual. Both male and female slugs inflate huge blue penises and later lay eggs.
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Travelling further afield, the rains of South Africa bring out swarms of bright red millipedes to find partners, and, in the caves of Venezuela, giant bat-eating centipedes lie in wait for their meal. These creatures, which can grow up to 13 inches, long capture bats on the cave ceilings.
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Insects can have a softer side to them, too. In one species of harvestman in Panama it is the males, rather than the females, that take care of the young.
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Producer – Peter Bassett
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Life In The Undergrowth:
Taking To The Air
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As the early June sun begins to set over a calm river in Central Hungary, masses of ghostly shapes emerge from their larval cases to take to the air for the first time.
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They are mayflies, and in a spectacular display, thousands of them show how the very first wings to evolve were used.
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As larvae, the mayflies have spent two years feeding and growing underwater but now it is time for them to begin their brief lives in the air.
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Insects have developed wings to help them find a mate and for mayflies the race to reproduce becomes a race against time.
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From the stunning aerobatics of hoverflies in an English garden to the mass migration of purple Crow butterflies in the valleys of Taiwan, this episode tells the tale of the first-ever animals to take to the air.
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Some insects display amazing flight abilities.
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Dragonflies are some of the most sophisticated of all flying insects, demonstrating supreme control over their aerial movements.
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Cascade damselflies are found only at a few isolated waterfalls in Costa Rica and Panama and display an extraordinary ability to fly through powerful cascades, seen on film for the first time.
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Having wings and being able to fly in the last stages of their life gives insects such as butterflies a huge advantage when it comes to finding new breeding sites and sources of food.
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As David Attenborough remarks: "With their fragile-looking wings and apparently erratic flight, butterflies might not seem to be the most powerful of fliers.
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"But in fact, they are accomplished aeronauts and they can fly hundreds of miles if necessary to find the food they need."
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However, flight does not come so easy to heavier insects.
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Bumblebees are generally heavy bodied and have employed a special trick to get them into the air, even on the coldest winter days.
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Beetles, on the other hand, keep their hind wings well hidden under hard protective wing cases to protect them as they forage for food.
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David finds the world's largest insect, the Titan beetle, a monster of the Amazonian basin.
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Producer – Mike Salisbury
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Life In The Undergrowth: The Silk Spinners
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Silk is the invertebrates' great invention.
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"Silk really is an extraordinary material," explains David Attenborough.
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"It is stronger than a steel thread of the same diameter but, unlike steel, it's elastic. It can stretch up to twice its length.
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"The inhabitants of the undergrowth developed the ability to produce this remarkable material very early in their evolutionary history over 300 million years ago."
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From the protective stalks of lacewing eggs to the amazing hanging threads of New Zealand's fungus gnats, invertebrates use it in a huge range of ways.
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A cave in New Zealand is illuminated by twinkling blue bio-luminescent lights produced by fungus fly larvae but the effect is as sinister as it is truly magical: the glowing blobs attract flies and moths which become snared in the silk to make a ready meal for the larvae.
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It is spiders, though, who have taken silk-spinning to extremes.
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The common wolf spider has no web, but the female is a gentle parent who encases her eggs in a silken bundle which she carries wherever she goes.
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Then there is the bolas spider that uses a ball of sticky silk coated in a copy of moth pheromone to lure moths in, and the infamous redback spider of Australia who uses silk to 'ping' its prey up into the air where they can be consumed at the spider's leisure.
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Silk is used by some communal spiders to create silken palaces that can rise 15 to 20 metres up in the forest canopy.
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Here, millions of tiny spiders work together to kill prey many times their own size.
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In the UK, gossamer is the creation of a million baby spiders that spin threads vertically from the top of bushes which will carry them off into the wind, enabling them to travel for miles.
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David concludes: "Silk can be used for transport, as well as looking after the young, courtship and, of course, catching prey. Ingenious though we are, we have not yet been able to invent anything as strong, as light or as elastic as silk."
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Producer – Bridget Appleby
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Life In The Undergrowth:
Intimate Relations
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The world of invertebrates is a web of relationships with plants and other animals, and this programme is full of incredible partnerships.
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It features unique footage of one of the world's smallest insects, a chalcid wasp known as a fairyfly.
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At only a quarter of a millimetre long, the fairyfly glides underwater in search of water beetle eggs to lay its own eggs.
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They are not the only insects who have come up with ingenious ways of finding a place to lay their eggs.
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The bot fly targets cattle in Brazil by catching other species of flies which spend a lot of time hanging around cows. The bot flies wait around cow dung where the flies come to lay their eggs and then ambush them to lay their eggs.
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Some insects have the ability to force a plant to make a home for them.
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In the upper reaches of the Amazonian rain forest are strange areas, sometimes the size of a football field, in which grow only one kind of small tree.
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These are known as 'Devil's gardens' by locals but, rather than being the work of devils, they are the work of minute Myrmelachista ants less than five millimetres in size.
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These ants 'farm' the particular trees that give them shelter and, in order to make sure they can grow without competition, the ants kill off all other types of seedlings in the surrounding vegetation.
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David Attenborough points out that among the animals of the undergrowth, there are many mutually beneficent partnerships.
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"But exploitation and deception can work just as well … and in any relationship there is a risk of treachery and deceit."
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Examples include the blister beetle, whose larvae huddle together on the end of a piece of grass and mimic a female bee to get themselves transported to where they need to be, and the blue butterfly caterpillar that tricks its way inside an ants' nest where it is fed, cleaned and cared for as if it were one of the queen ant's own brood until it is ready to emerge as a butterfly.
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One insect is in on this con, however, and uses it to its own advantage.
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Producer – Stephen Dunleavy
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Life In The Undergrowth: Supersocieties
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Just like mammals, invertebrates do not always operate alone. True sociality was the last feature to evolve in invertebrates as recently as the time of Tyrannosaurus.
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In the last programme of the series, David Attenborough explores the tensions below the surface in some of the great social structures built by insects.
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"We now know that every insect society is full of conflict, power struggles and mutinies," begins David.
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"Social insects construct the tallest of non-human buildings. They protect their colonies with great ferocity.
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"They increase the size of their societies at an alarming rate, and they're capable of mobilising huge armies to make wars on their neighbours."
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The sand wasp works hard to look after its young but the female is too busy to guard all her nest sites.
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Paper wasps in Panama, on the other hand, have learnt to group their nests together. The female wasp employs her sisters to look after her eggs.
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The nests are well guarded and the wasps rear more young than if they were to nest alone.
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Bees are renowned for their colonies but these colonies are rife with tension.
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For the first time, cameras have filmed the worker bumblebees turning on their queen and stinging her to death, behaviour that has only recently been discovered.
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