Sir David Attenborough focuses on the giraffe's super-elongated neck and the chameleon's stretchy tongue in this episode - two attributes that make their owners very curious creatures.

Chameleon

The chameleon is a truly bizarre creature in both its appearance and behaviour.

They have swivel eyes that work independently of each other, a grasping, prehensile, monkey-like tail, and their colour changes rapidly.

However, the most fascinating part of the chameleon is its incredible tongue, which can stretch to twice its body length and can accelerate up to five times faster than a fighter jet to hunt hard to reach insects. There's no escaping their sticky projectile.

Giraffes

The giraffe is an animal that can’t fail to impress. At up to 19 feet or 6 metres in height, the majority of that being neck, it is equally intriguing in appearance and mysterious in its biology.

It has taken science a long time to fully understand the amazing feat of biological engineering that keeps blood flowing the enormous distance from the giraffe’s heart to its head.

How has nature overcome the problems of being stretched to the limit?