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Gecko or skink?

Ever wondered if you're looking at a gecko or a skink? Here's a guide to help you tell the difference.

Omnivorous - eats insects such as moths and flies, berries and nectar

Gecko

Skink

Eats primarily invertebrates, along with       some fruit especially in summer

Excellent sight, smell and hearing

Excellent sight, smell and hearing

Large bulging eyes

Smaller eyes

Smells with its tongue

Smells with its tongue

Blinks its eyes to keep them moist and clean

Has clear eyelids that it licks to keep clean and moist

A well defined neck

No pronounced neck

Great climbing abilities, can "adhere" to surfaces and walk upside down. Learn more...

   Mostly ground dwellers, but agile climbers too

Vocal with clicks and squeaks

Somewhat vocal, squeaks

Gives birth to twins

Gives birth to up to seven offspring

Skin loose and velvety

Skin sleek and shiny

Scales small and granular

Overlapping rows of shimmering scales

More slender than a gecko

Rounded toes

Tapering, pointy toes

Can self-amputate tail

Sheds skin all at once, or in strips, to accomodate growth

Can self-amputate tail

     Sheds skin in small         patches to accomodate growth

Has a long tapering tail

Image: Anna Yeoman

 

The secrets of the sticky feet:

Gecko and van der Waals forces

Gecko are well-known for their incredible ability to climb vertical walls, cross ceilings and hang on the underside of tree branches. Their feet have been well-studied in the past, and have led to some interesting bio-mimicry technology, such as ways to seal wounds and sticky hand-held paddles to help soldiers scale walls. Yet ongoing research is showing just how complex the geckos’ adhesion system really is. 

 

Geckos stick to surfaces because their toes are covered in millions of microscopic hairs called setae. Each seta splits off into hundreds of even smaller bristles called spatulae. These spatulae get so close to the contours of the wall or tree that they tap into a special kind of electromagnetic force called van der Waals force. Van der Waals forces involve the creation of a physical bond between the electrons from the gecko hair molecules and the electrons from the wall molecules. As the electrons interact with each other they create an electromagnetic attraction.

 

Scientists have discovered how the balance of forces acting on the gecko, and the angle of its toe hairs, contribute to the creation of its successful stickiness. The setae on the gecko’s feet don’t stand up straight at a 90-degree angle, but instead branch off at oblique angles. Researchers have developed a mathematical model that shows that as the hairs bend at angles closer to horizontal, the surface area that the geckos stick to increases, and the geckos can support more weight. This system makes it possible for geckos to stick and unstick their feet so rapidly that they can race across surfaces at 20 body lengths per second. If, however, the surface is covered in too much moisture, the sticking powers are reduced. 

 

They have also discovered that setae are ultraflexible. When a gecko changes direction quickly or leaps to another surface, the setae and spatulae have to absorb huge amounts of energy and redirect it. The flexibility and stretchiness of the setae make this possible. 

Van der Waals forces involve the creation of a physical bond between the electrons from the gecko hair molecules and the electrons from the wall molecules.

Department of Conservation. Lizards. Department of Conservation.

Retrieved from: https://www.doc.govt.nz/nature/native-animals/reptiles-and-frogs/lizards/

 

Dickerson, K. (2014). Geckos' sticky secrets? They hang by toe hairs. Live Science. Retrieved from: https://www.livescience.com/47307-how-geckos-stick-and-unstick-feet.html

New Zealand Herpetological Society (2017). Herpetofauna (native).

Retrieved from: https://www.reptiles.org.nz/herpetofauna/native

 

Patterson, G. (Jul 2000). Skinks on the edge. New Zealand Geographic, 47.

Retrieved from: https://www.nzgeo.com/stories/skinks-on-the-edge/

 

Science Learning Hub – Pokapū Akoranga Pūtaiao (17 Dec 2009). Native skinks and geckos. 

Retrieved from: https://www.sciencelearn.org.nz/resources/1381-native-skinks-and-geckos

Bibliography

Contact us:

Email Grant Norbury at: norburyg@landcareresearch.co.nz

 

Tel: +64-21-1783604

Central Otago Ecological Trust
PO Box 282
Alexandra
New Zealand

 

Central

Otago

Ecological

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© 2019 Anna Yeoman for the Central Otago Ecological Trust