Original subtitles

It's been labeled the most exotic island chain in the world.

Pristine sands, azure blue seas

and colorful reefs make Zanzibar

a much loved holiday destination.

For centuries, the lure of ivory, spices and gold,

has attracted empire builders from across the globe.

But people aren't alone in their quest to set up home here.

Bizarre creatures, many of enormous size,

run wild throughout the archipelago.

And marine giants patrol the island shores.

Zanzibar is an untamed wilderness.

Zanzibar is a land of giants.

Lying 40 km off the east coast of Tanzania in Africa,

the Zanzibar archipelago

is dominated by two islands,

Unguja and Pemba.

Unguja is the larger of the two,

measuring just 100 km long by 30 wide.

Around 130,000 years ago,

the Indian Ocean sea levels began to drop.

Enormous fossilized coral reefs were revealed,

giving birth to Zanzibar,

and the many smaller islands surrounding its coast.

Some creatures began colonizing the island from day one,

but along with other primates,

people set up home here more recently.

2,000 years ago settlers arrived along Zanzibar's shores,

living simple lives governed by the tides.

Ever since, the islands have been a trade hub

between mainland Africa and Asia,

and the population has risen to around one million.

But Zanzibar still has a wild side.

And as the tides come and go,

the island's giant creatures reveal themselves.

Nothing looks more tranquil,

than warm tropical waves lapping over a white, sandy shore.

However, on Zanzibar's beaches,

there's far more than meets the eye.

Some of the island's earliest colonizers came ashore in search of food,

long before the arrival of man.

And they never left.

At low tide, shore-dwelling crabs

have important jobs to do.

Excavating and maintaining burrows

burns lots of energy.

Algae and fungu scraped off filtered sand particles

forms the bulk of this crab's diet.

Feeding is a production line process

leaving sand pallets dotted along the shore.

At low tide, black herons

are also on the lookout for a meal.

Although the crabs take cover...

This bird has bigger fish to fry.

For one species, mealtimes prove a little more challenging than to others.

Adult male fiddler crabs have an over-sized claw.

It's the violin-playing motion they make while eating that has given rise to their name.

Female fiddler crabs are better balanced than males

and cause quite a stir whenever they venture among the boys.

This frantic waving is all about catching the eye of a passing lady.

The faster the rhythm, the better the chance of being noticed

and outdoing the competition.

Females prefer fast wavers

and this male has struck the right chord

as his conquest enters his burrow.

Not all mating is a private affair.

Some females prefer using the safety of their own burrows

to incubate their eggs.

For male fiddler crabs, size also matters when it comes to protecting territory.

Shows of strength like these deter neighbors from cramping their style

and also keep potential squatters at bay.

As the new tide approaches, it's a scramble to retreat to saftey underground.

Those who've wandered too far from their burrows muscle-in on someone else's hard-earned home.

The turning of Zanzibar's tides governs the lives of many creatures.

But certain life forms have set up permanent home on dry land.

At just a kilometer long, and 300 meters wide,

Zanzibar's Chumbe Island reveals the fossilized coral

that forms the region's bedrock.

Devoid of soil, Chumbe's forest is home

to a highly-specialized plant community

that survives without any groundwater.

Giant roots spread out in all directions

and smaller species cling to any surface they can.

Many plants and trees get their water from the humid air.

Others like the baobab stockpile reserve

during the rainy season.

These are the green giants within this forest.

Lining the island's shore is another tall tree.

Although these coconut palms fall short on girth,

at 30 meters tall, they match the baobab for height.

This slender giant is key to the existence of a colossus creature

that thrives on the flesh of its seeds.

As night draws in,

the world's biggest creepy crawly reveals itself.

Weighing over 4 kg,

with a leg span up to a meter,

the coconut crab is the world's largest land-living invertebrate.

It's actually a giant hermit crab,

and while it's young, it carries another creature's abandoned shell on its back for protection.

Fully grown, it develops a tough outer skin.

It stays hidden during the day to reduce water loss from heat.

But at night, this solitary stalker

heads off in search of its favorite food.

Unlike most of its relatives,

the coconut crab can't survive in water.

It would drown if submerged.

Its gills have evolved to work like lungs

although they need to be kept moist in order to function.

Its antenna have also evolved,

enabling it to pick up airborne scents

the same way insects do.

This forest forager, along with others,

is on to something.

Also known as the robber crab or palm thief,

coconut crabs are great climbers.

They can't cut down coconuts by themselves,

however fallen fruits are quickly seized upon.

Although the surrounding sea is a no-go zone

for these land-based giants,

it wasn't always that way.

They started life in the water.

A female coconut crab makes her way to the shore.

She's been carrying a batch of eggs

glued to her abdomen for two months.

At high tide, they're ready to be released.

On contact with water, the eggs hatch immediately.

The juvenile giants eventually make their way ashore.

They live a hermit's life before becoming permanent dry-land residents.

Giants don't just live above Zanzibar's island shores.

Beneath the surface of the surrounding seas,

lie some of the biggest of all.

This coral reef is a living seascape

made up on millions of tiny plant-like animals

known as coral polyps.

Together, they act as a single super-sized organism.

Secreting calcium carbonate from their base,

the polyps form complex and striking sculptures.

Colonies grow over thousands of years,

eventually joining other communities to become a reef.

Some stretch 90 km across the ocean floor

and have been growing for over 50 million years.

Zanzibar hosts some of the most spectacular coral gardens in the world,

and over 90% of East Africa's hard coral species

are found here.

These rainforests of the sea

are at the heart of an entire underwater ecosystem.

Anemones, sea cucumbers, eels,

and an array of tropical fish,

make this underwater Eden their permanent home.

Further along the reef looms another giant.

Of the 400 or so species of ray,

the manta is the largest.

These alien-looking creatures

can grow up to an incredible seven meters across

and weigh as much as two tons.

They lead solitary lives

and only come together in large numbers

under certain conditions.

These manta rays have traveled far to this section of reef for a special service.

This cleaning station provides the opportunity

for a good once-over from attentive cleaner fish.

Flashes of blue and yellow advertise their presence.

The clients happily flood in.

But before the manta rays take up this service,

they need to form a queue.

Individuals size one another up

by swimming parallel to the reef.

Once a heirarchy is established,

they take turns swooping into the station.

Each species of cleaner fish

nibbles a different section to reduce competition.

This mutually beneficial relationship

provides the fish with a steady supply of food

and ensures the manta's skin

is free of dead cells and parasites.

Cleaning sessions can last up to three hours,

and once thoroughly scrubbed,

the manta rays head back into the deep.

Unlike many of their shark cousins,

these graceful giants pose no threat to other fish.

Manta rays are filter feeders,

and when plankton blooms,

everyone joins the feeding frenzy.

Filtering large volumes of water

they funnel the miniature prey into their gaping mouths.

A single manta can sieve up to 17 kilos of plankton a day.

Barrel rolling is a quick way of returning to a particularly dense patch of food.

As more manta join the feeding frenzy,

they're suddenly eclipsed by one of Zanzibar's greatest oceanic giants.

Whale sharks can grow to over 20 meters

and weigh up to 34 tons.

That's more than five African elephants.

They are by far the largest fish in the world.

Dwarfing everything in their wake,

they survive on some of the smallest organisms in the ocean.

They can sift over 6,000 liters of water an hour.

Fine filters, also known as gill rakers,

trap any organism over two millimeters wide.

Most species of shark wave their tales

to propel themselves.

However whale sharks are unique

in moving their entire bodies from side to side.

They remain close to the surface

and their top speed is a modest five kilometers per hour.

It isn't just giants that are attracted

to these plankton blooms.

Smaller fish also move in to feed.

But dining with this particular giant has its downside.

These fishermen have just received a precious sign.

Knowing where and when to cast their nets

is the key to a good catch.

The whale shark's tale act as a valuable time-to-go-fishing flag.

This small dugout canoe makes light work of catching up with the shark.

Their efforts pay off.

It would normally take a whole day to land a haul of this size.

Guided by their giant neighbor,

the fishermen's nets are soon full.

As aquatic giants patrol the shores,

on one island, a unique species of primate

has taken refuge in the trees.

Unlike most in Zanzibar's archipelago,

Pemba Island is formed from a true landmass

rather than coral reefs and sand banks.

Lying 40 km north of Unguja,

rolling hills and forested valleys

have earned Pemba another name, Green Island.

The region's vast number of trees

are home to one of the rarest primates in the world.

Isolated from mainland Africa for over 10,000 years,

the Zanzibar red colobus monkey

has evolved to become a distinct species.

Its color and some of its habits are unique.

Feeding is a group activity that begins in the early morning.

Colobus are leaf eaters.

Leaves are highly nutritious,

but most animals are unable to digest the cellulose

that makes up plant cell walls.

Colobus monkeys have a solution.

They have a four-chambered stomach,

like many hooved animals,

which enables bacteria to ferment

and break down what they eat.

After an hour or so's munching, it's time to rest.

Their peculiar digestive system

leads to long periods of inactivity.

Up to 70% of the time, they're awake.

But not all members of this troop are sleepy.

Unlike most other monkeys,

young red colobus continue suckling

for around 18 months.

Energy from their mother's milk is quickly converted.

And while the grownups take a nap,

the youngsters decided it's time to play.

For an adult red colobus monkey,

grabbing a peaceful 40 winks is easier said than done.

Alongside the annoying antics of the troop's teenagers...

The process of digesting large volumes of leaves

creates an inevitable byproduct.

Methane and carbon dioxide

are two gases these youngsters will just have to learn to live with.

Zanzibar's red colobus are also fond of unripe berries and seeds.

Unlike many primates,

their stomachs can't digest the sugars contained in the more mature fruit.

Here on Pemba Island

is a giant creature that does have a sweet tooth.

The Pemba flying fox is the largest bat in the world.

It has a wingspan in excess of a meter-and-a-half.

Most other bats use acute hearing to capture insects,

but flying foxes rely on large eyes

to track down their meals.

Blossom, nectar and ripe fuit

make up the majority of their vegetarian diet.

These mega-bats have excellent vision

and good hearing.

They're also very vocal,

especially when neighbors get a little too close.

Living in large groups of up to 850

has its downside.

Especially when all you want to do is sleep.

But as night draws in,

the inconvenience of sharing a tree with so many

reaps its reward.

Flying foxes split up in search of food.

When they return to the roost,

different scents indicating which trees are in fruit

are shared among the entire group.

Individuals now know where to forage the following night.

While Pemba Island's flying foxes

help pollinate plants and disperse seeds,

another mammal causes nothing but trouble.

Vervets are medium-sized monkeys

that hang around in troops of up to 50.

Unlike the island's red colobus

that suckle for well over a year,

vervet youngsters nurse for approximately four months.

The school of hard knocks starts early in vervet society,

and this troop are up to no good.

Fruits, berries and leaves

make up a large part of this monkey's diet.

But one of their favorites fruits is cassava.

This starchy, tuberous root is full of carbohydrates,

and is one of the most drought-tolerant crops on the planet.

After rice, cassava is the second-most important food crop

throughout Zanzibar.

Protecting their precious fields

is a constant battle for Pemba's farmers.

The vervets realize they've been spotted

and scramble back to the trees.

The farmer's catapults and sticks

act only as a temporary deterrent.

The vervets don't just pose a problem to people's livelihoods.

One of the island's animal residents often falls foul to this monkey's antics.

They've dislodged a mother and baby flying fox from their tree.

Unable to take off from the ground,

the farmers realize the pair need help.

20 years ago, these giant bats

were virtually hunted to extinction

by local islanders.

Today the species is protected.

The Pemba people realize the important role the bats play in dispersing pollen and seeds.

They're vital for keeping the region's forest alive.

On Unguja Island, the tide retreats

and local women go to work.

The Nungwi people have hunted along these shores for centuries.

They're searching for food, but in particular, octopus.

Every nook and cranny is checked.

The octopus could be hiding anywhere.

Finally, one of the group may be in luck.

Finding an octopus is one thing.

Coaxing it out of its lair is another.

Collecting octopus is a way of life for the Nungwi,

as well as putting food on the table.

Any excess catch is sold to the local market.

Over-hunting is avoided by only fishing on the last days of the month,

when the tides are at their lowest.

Zanzibar's tides also support another local business.

Seaweed is used all over the world

as an ingredient for fertilizers,

cosmetics, even cheese.

Pegs, set 10 meters apart

are joined by a network of ropes

to which plant cuttings are tied.

The seaweed remains submerged in these inter-tidal lagoons

and takes around two months to grow.

Once harvested, the plants are hung out to dry in the sun.

Zanzibar exports around 700,000 tons

of seaweed every year.

And most famous make around $40 a month.

Although seaweed is highly prized by humans,

one of Zanzibar's aquatic creatures

is especially fond of it as well.

At high tide, green turtles enter the lagoons

to feast on any floating fare.

When young, these amphibious reptiles

feed on jellyfish, shrimps, the small fish.

Measuring over a meter long

and tipping the scales at around 200 kilograms,

it's only during adulthood

that these green giants become strictly vegetarian.

Apart from when they're nesting, green turtles rarely come ashore.

However one of their giant relatives

has set up permanent home on Zanzibar's Changuu Island,

less than five kilometers away.

At over 250 kilograms in weight

and with a shell length approaching one-and-a-half meters,

the aldabra is one of then largest tortoises in the world.

It's one of the longest-lived animals too.

Some live for over 200 years.

Giant tortoises feed mainly on grasses and woody plants.

Whenever these aren't within reach, dried leaves will do.

This crunchy meal contains very little moisture.

So aldabra tortoises draw on a special method to re-hydrate their enormous frames.

The fat stored beneath their shells

can be converted to water.

Burning these reserves releases fluid during the hottest parts of the day

and prevents them becoming dehydrated.

Changuu's giant tortoises can survive without water for long periods.

But for creatures less fortunate,

another location provides a permanent wetland.

On Zanzibar's Unguja Island,

the shoreline boundary isn't clearly defined.

Small estuaries venture into forests,

forming a unique relationship between land and sea.

Mangroves thrive in saline coastal habitats.

A complex system of aerial roots enables the intake of oxygen

and traps organic debris

that would otherwise be washed out to sea.

These tidal swamps provide a breeding ground

and nursery for several species of fish and invertebrates.

Many of these will head out into the surrounding reefs and seabeds when adults.

Some species of mangrove have developed a unique method of reproducing.

The seeds germinate and become fully-fledged seedlings

while attached to the mother plant.

These pods are then released, allowing them to immediately take root.

Or they can remain dormant to float further afield.

Adjoining the mangrove, is the largest reserve of mature woodland

in the entire archipelago.

Living fossils, like this cycad tree,

have remained unchanged for millions of years,

a lineage stretching back before the dinosaurs.

Similar to pine trees,

this species doesn't produce any flowers.

However, unlike their relatives,

each cycad tree produces only male or female seed cones.

These colorful structures can be up to a meter long

and weigh over 30 kilos.

It's no wonder, even herb-loving dinosaurs

became such giants too.

Jozani Forest lies at the heart of the island.

Alongside the vast array of birds, insects and reptiles,

it's home to two species of primate.

Sykes monkeys eat virtually anything,

leaves, ripe fruits and flowers,

Insects, and even small vertebrates.

However, not every prey makes an easy picking.

Zanzibar's giant carpenter ants

also have a giant bite.

At around two centimeters in length,

they put up a strong defensive fight.

This monkey soon realizes it's bitten off more than it can chew.

Jozani's other primate, the red colobus monkey

is a strict vegetarian.

It's identical to the species found on Pemba Island,

except this particular population

has come up with a unique solution

to their ongoing wind problem.

Instead of sitting around feeling bloated after a bellyfull of leaves,

these monkeys are on a mission.

They single out their target...

And wait for the right moment to strike.

Without warning, they launch their attack.

It's a constant battle for the island's charcoal sellers.

Here in Jozani, red colobus have long worked out

that eating charcoal aids the digestion of exotic leaves.

This learned behavior passed down from mother to young

is unique to Unguji's troops.

As night draws in,

another of Zanzibar's giants emerges from the shadows.

This is no ordinary rat.

At over a meter in length,

it's one of the largest in the world.

Known as a giant pouched rat,

it's able to store vast amounts of food

in its expandable cheeks.

Its eyesight is very poor,

but is compensated for by an excellent sense of smell and hearing.

Its giant nose is so sensitive,

scientists have begun using this species

to sniff out land mines

and detect human diseases, such as tubercolosis.

To avoid predators, the rat changes its burrow site every two weeks.

And this may not be a bad thing.

A unique species of leopard is still thought to roam these woods.

Legend has it many were kept by witches

and used to hound local villages.

Because of this supernatural association,

the island's leopard has been hunted to the brink of extinction.

Zanzibar's giant rat population however

continues to flourish.

Zanzibar is an island paradise.

People live by the turning of the tides.

And its isolation has seen Zanzibar's creatures

evolve and grow.

Many mainland species are forced to remain small

to escape predators,

but island animals have an easier life.

Abundant food, less competition

and fewer predators have had a positive effect.

They've allowed Zanzibar, and its many islands,

to become a wilderness of giants.