It's Lizard Week on iNaturalist! Apr 17 - Apr 23, 2016

This week the Critter Calendar we’re focuses on a charismatic group of reptiles who have an almost worldwide distribution and inhabit most terrestrial ecosystems on Earth - the lizards! There are several taxonomic definitions of lizards, and for the purposes of the Critter Calendar we are focusing on a fairly traditional view, which includes what’s in the suborder Sauria on iNaturalist. You can check out our Sauria page to see which families are included on the left-hand side.

So just what is a lizard? For the most part we all know one when we see one, but some can be tricky and as lizards are an evolutionary grade, they are often defined negatively, through differences between close lizard relatives like snakes and the tuatara.

  • Lizards, like all reptiles, have scaly dry skin. Lizard scales can take on many forms - some are granular and pebbly, some are smooth and plate-like, while others are spiny and overlapping. Many lizard species will have several types of scales, such as the Night Lizards, who have large plate-like scales on their head and tiny granular scales over the rest of their bodies.
  • Most lizards have eyelids and external ear openings, which snakes lack.
    Most lizards have four limbs. Some, however, have only vestigial limbs and others such as the Glass Lizard are completely limbless.

  • Many lizards can “drop” their tails when threatened. Snakes are not able to do this.
    Unlike snakes, the internal organs of lizards are not linearly arranged. Lizards also have two functional lungs - snakes have only one functional lung.

  • The Tuataras of New Zealand has a slightly different skull than lizards do, and are the only extant members of the order Rhynchocephalia.

Some familiar and/or interesting types of lizards are:

Monitor Lizards (Family Varanus) - An ancient family found in Asia, Africa and Australia, these lizards have a triangular-shaped head, forked tongues, long necks and powerful legs and tails. The world’s most massive lizard, the Komodo Dragon, belongs to this family.

Geckos (Infraorder Gekkota) - Named for the chirping sounds they make, Geckos are mostly nocturnal and most geckos have incredible adhesive feet which allow them to climb on many surfaces. The majority of geckos also lack eyelids and must clean the transparent membrane over their eyes by licking it.

Chameleons (Family Chameleonidae) - a bizarre group of Old World lizards with zygodactylus feet, long extendable tongues, and eyes which can move independently of each other. Many are able to change their skin’s color but this is done more for communication and not for camouflage.

Skinks (Family Scinidae) - lizards with long bodies, no pronounced neck, and short or nonexistent legs. Most skinks are adapted to moving quickly along the ground, almost like a snake, but some, such as the endangered Solomon Island Skink, live arboreally. This species even lives in social groups called circuli.

If you see a lizard this week, Share your findings with us on iNaturalist, we’ll be keeping track here. Happy lizard hunting!

Posted by loarie loarie, April 21, 2016 05:42


I think more people could participate in the Critter Calendar projects if only they were more visible.

Posted by scubale over 5 years ago (Flag)

@scubale -- on every person's dashboard, it shows the critter of the week. It's quite engaging! I've been trying hard to hunt for each critter of the week. :)

Posted by sambiology over 5 years ago (Flag)

Would it be possible to add a "join this project" button on this page (the critter of the week description page)?

Posted by liesvanrompaey over 5 years ago (Flag)

@sambiology I'm sorry but I can't see it in my dashboard.

Posted by scubale over 5 years ago (Flag)

@scubale that might be because it only displays for people with their locale set to English?

Posted by loarie over 5 years ago (Flag)


I tried to change settings, restoring the English language, but I still don't see any reference to the project in my dashboard.
Maybe because I haven't Customized a few aspects of the site for a place, like common names?
(My box "Place" is empty.)
I think this should be irrelevant.

Posted by scubale over 5 years ago (Flag)

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