Page 17 - Atlas Of The World's Strangest Animals

NAMIB WEB-FOOTED GECKO 17

Comparisons

Apart from skinks (family Scincidae),geckos are one of the most are dwarf geckos – Sphaerodactylus ariasae and Sphaerodactylus
diverse groups in the reptile kingdom.There may be as many as parthenopion – which are both less than 1cm (0.4in) long.That’s
900 separate species and they come in all sizes.The two smallest 14 times smaller than the biggest web-footed gecko!

Sphaerodactylus parthenopion

Web-footed gecko

Six-lined racerunner

contrast, web-footed geckos have thin, almost translucent, Namib web-footed gecko habitats
pink skin, which makes them virtually invisible when
viewed against the dusky desert sands.

Strange sights
According to John Heywood’s book of proverbs (1546)
‘All cats are grey in the dark.’ It’s a saying that holds true
for humans.We see poorly in the dark – generally just
fuzzy tones of black and white. So it’s easy to imagine that
geckos would have a hard time finding their way around at
night. Not so. New research has revealed that they may see
better in the dark than we do.
All geckos have extremely large eyes to gather as much
light as possible.Those species that are active during the
day tend to have rounded pupils, but nocturnal reptiles,
like the web-footed gecko, have vertical pupils. By day,
these pupils narrow to tiny slits to protect the sensitive
retina at the back of the eye from damage.According to
researchers from Lund University, Sweden, this ‘design’ has
other advantages too. It seems that slit pupils allow those wave lengths.With round pupils, parts of the lens is
animals with colour vision to see sharply focused images at covered every time the pupil expands or contracts.With a
night – something that no human can do. slit pupil, the whole diameter of the lens remains
Light travels at different wave lengths depending on its uncovered, allowing every colour to stay in focus.What’s
colour. Human eyes have single-focus lenses, which means more, according to specialist work on nocturnal vision,
that not every colour is in focus when it hits the lens. colour vision is much more common in the animal
Many animals solve this problem with multi-focus lenses, kingdom than was once assumed, and geckos probably
where different parts of the lens are ‘tuned in’ to different have excellent colour, as well as night, vision.

(c) 2011 Marshall Cavendish. All Rights Reserved.