Original subtitles

(dramatic musical tones)

- [Narrator] A country in Central America

has become the kingdom of two very different lizards.

The basilisk carves out a carnivorous existence

while iguanas choose a slower pace of life.

In such a competitive realm, both species

are capable of performing strange

and seemingly impossible feats in order to survive.

With very different tastes in food,

the two species rarely come into contact.

But when the newborn reptiles

take their first steps into their forest domain,

battle commences.

In the war of contrasting lizards,

(ominous music)

survival is no guarantee.

(upbeat music)

In Central America, there is a land of endless rainforests.

(slow music)

Costa Rica.

(slow music)

Over a third of this foliage rich country

has become a nature reserve.

(slow music)

As a result, natural habitats thrive

and create a home for around 5% of Earth's species.

(serene music)

Birds of extraordinary vibrancy flourish

in the lush forest canopy.

(slow music)

Incredible colors are somewhat of a trend

of Costa Rica's wildlife.

The platinum jeweled scarab beetle

is perhaps the most radiant of the forest inhabitants.

(slow music)

It is believed its immensely shiny body

reflects its surroundings, camouflaging the beetle

against the dense foliage.

Larger creatures also reside in the bountiful trees.

(slow music)

Sloths can be found high in the forest canopy.

(slow music)

With plenty of food on offer,

the distinctive mammal can enjoy a slower pace of life.

(slow music)

Below the trees, there are yet more

wild wonders to discover.

Lizards are abundant in Costa Rica.

At only around five centimeters in size,

slender brown anoles survive amongst the forest vegetation.

(upbeat music)

(birds chirping)

Males use an extendable flab of skin

below their jaw, called a dewlap,

to communicate with potential mates.

(upbeat music)

(birds chirping)

The elaborate display seems to have the desired effect.

(upbeat music)

Further down, there are even stranger creatures.

This snakelike body, in fact,

belongs to another species of lizard.

The streamline reptile can move rapidly

along the forest floor.

(upbeat music)

Of all of Costa Rica's many species of lizard,

there is one that is famed for its intimidating appearance

and fierce nature.

The green basilisk.

The distinctive lizard's fearsome features

gave birth to their namesake.

Basilisk originates from a terrifying monster

of Greek mythology.

As their predatory appearance suggests,

basilisks are carnivorous.

(menacing music)

Straying into this lizard's territory

is a fateful mistake.

(menacing music)

It's not just insects on the menu,

a basilisk will take on anything it can fit in its mouth.

Even its own kind.

(menacing music)

Victims are swallowed whole.

With a third of the country

being a protective nature reserve,

Costa Rica has become a sanctuary

for more than 70 species of lizard.

Among the distinctive creatures,

there is one that dwarfs others.

(serene music)

At two meters in size, the green iguana

is the largest lizard in Central and South America.

(serene music)

The huge reptiles live in large groups.

(serene music)

Like the basilisks, they strike a fearsome appearance.

(serene music)

Hardened scales act like a protective suit of armor.

(serene music)

To complement their formidable looks,

green iguanas are also equipped with sharp claws.

Genders are easily identified.

(serene music)

Males have swollen cheeks, clad with enlarged scales.

(serene music)

Females, on the other hand,

strike a more understated appearance.

(serene music)

They may be known as green iguanas,

but they, in fact, come in many different colors.

(serene music)

Some of the lizards lack fully grown tails.

Their distinctive stumps are evidence

of the iguana's ability to shed their tales when attacked.

Fortunately, they do grow back, given time.

Despite their bulky frames, the lizards are at home

navigating the forests many trees.

Their fearsome looking claws are, in fact,

specialized for climbing.

(playful music)

They may look predatory, but these lizards

show little interest in passing insects.

(playful music)

Wandering invertebrates are simply an irritant,

rather than a tasty treat.

(playful music)

The large lizard has a much different taste in food.

(playful music)

These fearsome looking creatures are strictly vegetarian.

Leaves are their staple food source.

(playful music)

Herbivores may be a rarity in the lizard world,

but green iguanas have a ravenous appetite

and will consume as much plant life as possible.

Juicy fruits are a particular delicacy.

Flowers are also on the menu

and the lizards will go to extreme lengths

to get to the flowery feasts.

(upbeat music)

Known to consume around 30 different kinds of plants,

green iguanas have little chance of going hungry.

It is believed that they evolved to become herbivores,

so not to clash over food with carnivorous lizards,

like the aggressive basilisk.

(birds chirping)

Over millions of years, green iguanas

have become perfectly adapted to life in Costa Rica.

They start their day off in a lethargic state.

(slow music)

The lizards are awake, but movement is minimal.

(slow music)

As ectotherms, they rely on the sun

to warm their body temperature.

Thermal imaging shows the waking iguana

is only 25 degrees Celsius.

As the sun rises, the lizard begins to warm.

(upbeat music)

By 8 a.m., the iguana finally hits

its perfect body temperature of 36 degrees Celsius.

(upbeat music)

(birds chirping)

As they have relatively large bodies,

they take a long time to warm up.

After a morning bask, the iguanas can eventually head out

in search of food.

(upbeat music)

With food readily available, the longest an iguana

will travel from its home is a mere 100 meters.

There's no chance of the plants running away,

so the large lizards can afford to cruise

at a steady 3 kilometers per hour.

Once the best location is found,

their morning feast can begin.

But after just 15 minutes, the dining iguana

is forced to cut its meal short.

(slow music)

(birds chirping)

Bloated with food, the lizard must head back to bask.

Their need to rest is a consequence

of their vegetarian lifestyle.

(slow music)

Plants contain cellulose, which are particularly tough

to break down.

Iguanas do have plenty of microorganisms in their intestine

to aid digestion.

However, these organisms need to be close to 40 degrees

to function properly.

(slow music)

To achieve this, iguanas must keep still

for 96% of the day.

(birds chirping)

It is an effective method, but being static

for such long periods can leave an iguana

dangerously exposed.

(ominous music)

A post-breakfast sunbathe can become a matter

of life or death.

(ominous music)

Unbeknown to the resting iguana,

a huge boa constrictor is making its way

up the lizard's tree.

(ominous music)

Just as it gets within striking distance,

the usually docile iguana dodges the formidable snake.

(ominous music)

But it is not enough to deter the persistent predator.

(ominous music)

With nowhere else to run, the iguana has only one option.

A leap of faith.

(ominous music)

The large lizard makes a surprisingly good swimmer.

While basking, the cunning reptiles usually pick branches

that hang above water.

Diving into the unknown is the iguana's

last ditch survival tactic.

(birds chirping)

The carnivorous basilisk is also not afraid

to enter the water

and has no problem navigating its way

through the aquatic world.

However, they are not alone in the river.

This is also the domain of the spectacled caiman.

(upbeat music)

Reaching up to three meters in length,

it dwarfs the basilisk.

(upbeat music)

Stealthily, the caiman stalks the floating lizard.

(upbeat music)

Once within range, there is no escape.

(drum banging)

(water splashing)

(upbeat music)

A basilisk stands little chance of outswimming a caiman.

But it does have a secret weapon.

(water running)

These lizards can literally run on water.

(upbeat music)

This extreme form of propulsion

is much faster than swimming.

(upbeat music)

To achieve this seemingly impossible feat,

basilisks pull off some astonishing footwork.

(upbeat music)

The speedy lizards make 20 steps per second to stay afloat.

(upbeat music)

All their momentum stems from their powerful rear legs.

(water splashing)

(upbeat music)

Web-like folds between the basilisk's claws

open when in water, creating a larger surface area.

(upbeat music)

The first phase of this incredible stride

is a powerful slap.

(water splashing)

Force generated by the impact

produces a mass of air around the lizard's submerged legs.

(water splashing)

This perfect technique creates less water resistance

and allows the basilisk to lift its legs out of the water

at astonishing speeds.

They can keep up the lightning quick pace

for around 20 meters, giving them more than enough distance

to escape a pursuing predator.

As November awakens, Costa Rica is entering

the hottest and driest season of the year.

(slow music)

As ever, iguanas bask in the morning sun.

However, this male's coloration has dramatically changed.

He has turned orange.

The change in color is called nuptial coloration

and happens during the mating season.

(slow music)

(birds chirping)

At this time, males partake

in a peculiar head shaking ritual.

The unusual display is an iguana's way

of communicating its presence to its rivals.

(upbeat music)

A shaking head is a clear warning

to any potential trespassers.

(upbeat music)

Even with all the frantic displaying,

males still come face to face.

(upbeat music)

Fights erupt all around the canopy.

(upbeat music)

Those with the best treetop position

must be willing to fight to keep hold

of their prized real estate.

In the land of the iguana, encroaching onto another's patch

is an act of war.

The incumbent treetop male must decide

whether he wants to risk all and take on

the approaching intruder.

However, the defending iguana

has not mastered treetop warfare.

Crashing to the ground, the clumsy male

hasn't just had a hefty fall,

he's also lost his prized territory.

Only the strongest will be able to secure mating rights.

(bird shrieking)

During this season, males will spend most of the day

battling for dominance.

(upbeat music)

As the iguanas reach the middle of their breeding season,

the fighting begins to calm down.

(birds chirping)

Those that have fought well

have been able to secure a harem of females.

For the successful fighters, the real work starts now.

(upbeat music)

Males with harems would get back to their head shaking ways.

Although this time, the iguana does not want

to scare anyone off.

(upbeat music)

He is trying to impress his females.

(upbeat music)

But the wooing tactic is having little effect.

(upbeat music)

Undeterred, the male carries on.

(upbeat music)

No matter how hard he shakes his head,

the female shows zero interest.

Finally, the persistent male takes the hint.

(upbeat music)

A female iguana will only be receptive to a male's advances

on a few days within the breeding season window.

To stand any chance of mating,

the head shaking lizards must keep their act up

for days on end.

Persistence seems to be key.

With a female closing in, it could be

this male's big chance.

But unfortunately for the doting lizard,

he is simply in the way.

The head shaking must go on.

For those without a harem, they must be more opportunistic.

(bright music)

Scrambling up a tree, this male has sensed

a chance of romance.

A female straying from her harem is an opportunity

too good to miss.

Rushing the stray iguana, the male latches on

to his potential mate.

(upbeat music)

This could be his only chance to extend his bloodline.

However, he is not alone.

The scuffle has lured another male.

(upbeat music)

Chaos erupts over the trapped female.

(upbeat music)

Such force does not go down well.

(upbeat music)

As soon as the bullied female gets a chance,

she leaps to freedom.

(upbeat music)

The two forceful iguanas need to work

on their social skills.

In contrast, a male with a harem

has been taking a more subtle approach

and patience is a virtue.

His constant displaying is finally paying off.

Two months after mating, there is a change

in the female iguana's behavior.

Their appetite has dramatically decreased.

The change in eating habits signifies

they are close to giving birth.

At this time, expectant mother's abdomens

are packed full of eggs.

With no space left for food,

this female is on the verge of laying.

(cheerful music)

To give birth, she must first descend from the canopy.

(cheerful music)

Once on the forest floor, the mother to be

needs to find the best spot to lay her precious cargo.

(cheerful music)

A disused animal den adjacent to a river

is the perfect location.

Before laying, the iguana must further excavate the cavity.

(birds chirping)

In total, she lays around 80 eggs.

For now, her work is done.

The heat from the ground will incubate the developing eggs.

(thunder roaring)

June hails the start of Costa Rica's rainy season.

It has been three months since the iguana's spawned.

(rain falling)

In contrast to the frantic breeding season,

both male and females have become less active

during the day.

(rain falling)

The falling water cools down the lizard's body temperature,

zapping them of vital energy.

(rain falling)

(slow music)

While the rain falls, the eggs continue

to develop underground.

With their mother giving them

the perfect incubation chamber,

the developing lizards are ready to hatch.

(slow music)

From the tiny shell, emerges a perfectly formed

30 centimeter long iguana.

(slow music)

It takes an hour for the newly hatched lizard

to free itself from its egg.

After a couple of days, the newborn iguana

takes its first steps into the outside world.

(cheerful music)

It's not the only one braving the outdoors.

All the siblings have surfaced together.

(cheerful music)

(upbeat music)

It doesn't take long for the newborn iguanas

to get used to life in the trees.

(cheerful music)

Once outside their incubation chamber,

the young lizards stick together.

(cheerful music)

However, they cannot rest forever.

Finding food is a priority.

(cheerful music)

From the get-go, iguanas feast on anything

that is soft and green.

(cheerful music)

For the first few months of their lives,

the tiny lizards will stay together as a family group.

(cheerful music)

Through day

(cheerful music)

and night.

(cheerful music)

The sibling lizards maintain constant contact.

(cheerful music)

Evolving to become herbivores

is believed to be the main reason

for the green iguana's success.

They can be found throughout the tropical zones

of Central and South America.

And not just in rainforests.

Some iguanas have even taken to a more urban lifestyle.

A small town in Northern Costa Rica

has become a hotspot for the large lizards.

Thanks to their ability to feed on a variety of plants,

iguanas thrive in the urban environment.

(upbeat music)

And have even become a hit with locals and tourists, alike.

(upbeat music)

There are plenty of newborns taking their first steps

into their urban home.

(upbeat music)

They can be found all over town.

(upbeat music)

Darkness provide the tiny iguanas with plenty of food.

Soft flowers are perfect for the little lizards.

(upbeat music)

Wherever there is tasty foliage to be had,

green iguanas thrive.

(upbeat music)

It's not just iguanas venturing into the outside world.

Newborn basilisks are also taking their first steps.

From the get-go, they commence a predatory life.

(menacing music)

Insects are the growing lizards' main targets.

Their lightning quick reactions

allow the hungry basilisks to catch plenty of prey.

In contrast to the iguanas,

the predatory lizards go it alone

and get their meals to themselves.

However, the hunting instinct

can often lead the young reptiles into danger.

(menacing music)

(water splashing)

Fortunately, this basilisk has already mastered the art

of running on water.

But the lizard is not out of the woods yet.

(water splashing)

It is fast becoming an escape artist.

(birds chirping)

Weighing less than an adult,

young basilisks are actually better at running on water

than their elders.

(upbeat music)

Lighter on their feet, they can even change direction

on the fly.

(ominous music)

This incredible ability helps young basilisks

survive a solitary life.

(ominous music)

(water splashing)

(birds chirping)

Unlike the lone hunters, the newly hatched iguanas

are still sticking together.

(birds chirping)

Sprouting grass offers the tiny lizards a fresh feast.

(birds chirping)

However, life at ground level is risky.

(birds chirping)

(ominous music)

An adult basilisk has entered the iguana's feeding grounds.

(ominous music)

Frantic head movements indicate the predator

is locking onto a target.

(ominous music)

Straying into the basilisk's strike range

(ominous music)

is a fatal mistake.

(slow music)

The unfortunate lizard is swallowed whole.

A lone iguana stands no chance

against a surprise basilisk attack.

(slow music)

To while the supreme hunter remains in the area,

all of the young lizards could face a similar fate.

(ominous music)

(birds chirping)

Succumbing to the basilisk seems inevitable,

but there is hope for the iguanas.

(cheerful music)

When they stick together, they have many eyes

ready to alert the group of danger.

(cheerful music)

Once the alarm is raised, the cunning juveniles split off

in different directions, confusing their deadly pursuer

and allowing the fleeing lizards to escape.

(cheerful music)

For the young iguanas, their greatest strength of all

is unity.

(birds chirping)

Costa Rica's protected forests provide the iguanas

and basilisks with a home unspoiled by man.

To survive, the lizards have evolved in very different ways.

The basilisks use their fierce predatory instincts

to carve out a living, while iguanas thrive

on a vegetarian diet.

As a result, the two lizards do not compete over food.

However, there are many threats

from other forest inhabitants.

Both have developed unique methods

to avoid would-be predators and even each other.

They may clash and live contrasting lifestyles,

but the fierce and gentle lizards

have both become legends of Costa Rica.

(upbeat music)