By Ella Davies
Earth News reporter
Labord's chameleons grow up fast
The short but spectacular life cycle of the Labord's chameleon has been filmed by BBC documentary makers.
The lizards live for no more than five months after hatching.
They then grow rapidly until they reach maturity, when adult females develop vibrant colours to attract a mate before laying eggs and dying.
The annual lifecycle of these reptiles reflects the extreme seasons in southwest Madagascar, according to scientists.
Labord's chameleons (Furcifer labordi) are the shortest-lived land vertebrate in the world and are only found in the forests of southwest Madagascar.
During the dry season the whole population of chameleons consists of just eggs.
Incubating for approximately eight months, they hatch synchronously at the start of the wet season.
The chameleons rapidly develop into adulthood, taking advantage of the increase in insect prey that also emerges with the rains.
Once they have mated, the females lay their eggs and all of the adult chameleons die off as the dry weather returns.
According to Dr Kris Karsten, whose study of the unique chameleon was published in the journal PNAS, this remarkable annual lifestyle is very rare among reptiles.
"About a dozen species of lizards experience very high annual turnover... However, for those species, their maximum longevity is [greater than] one year since some survive for a second year," said Dr Karsten.
"In contrast, Furcifer labordi is a chameleon with only four to five months as their maximum longevity, and so their entire lifecycle - not just post-hatching life span - is annual."
Insects often have short life cycles. Adult mayflies live for as little as 30 minutes - enough time to reproduce before dying
The pygmy goby, a tiny coral reef dwelling fish, lives for just 59 days
Shrews are some of the shortest-lived mammals, living for 14-19 months
According to Dr Karsten, chameleons are difficult to study in the wild because of their excellent camouflage and secretive behaviour.
A BBC crew filming for the series Madagascar aimed to capture the chameleons' life cycle in full.
With populations limited to a handful of forest patches, the team relied upon keen-eyed guides to locate the lizards.
Timing provided the biggest challenge for the film crew however, as they attempted to film the chameleons' brief lives.
"An animal that lives its life in 12 weeks changes so fast that you have to be there at exactly the right time to catch them as small babies and at the moment they start to fight for mates," said researcher Emma Napper.
The crew captured footage of the hungry young chameleons feasting on spiders and other insects.
"The babies were real characters, they looked very cute but had a voracious appetite, trying to eat anything that moved," said Ms Napper.
"This is important for them as from the moment they hatch, they are in a race to grow up."
Growing up to 2.5mm a day, the young chameleons soon developed into adults.
The females underwent a dazzling transformation as they adopted vibrant mating colours to attract males.
The males meanwhile engaged in hissing, grappling fights in their pursuit of females.
The chameleons' colourful and crucial mating behaviour
Successfully mated females then laid their eggs before the dry weather returned, the adults died, and the cycle began again.
Scientists attribute the "bizarre" life cycle of these chameleons to the extreme changes in weather in southwestern Madagascar.
They propose that spending the majority of their lives incubated in an egg is an adaptation that allows the chameleons to survive even when food is scarce.
"What further studies of these chameleons can also do is help us better understand mechanisms of aging and the evolutionary drivers of life span," said Dr Karsten.
"There are probably so many more equally fascinating things left to be discovered about the herpetofauna of Madagascar."
Madagascar concludes on BBC TWO at 2000 GMT on Wednesday, February 23.