Reptiles & How To Tell One From Another.

John Grundy News, Revealing Reptiles


At first glance and often in a split second, as a reptile retreats from your advance, it is very difficult to tell if the animal you have just seen is one previously spotted.

Hammerhead gets his name from the T piece connected to its head marking.

So how do we begin to spot the difference? Are there any features in a reptile’s face or markings that set it apart from others in the area? Fortunately for us there are. But it takes time to see these features.

Malcolm X. Very distinguishing head markings.

With patience (there’s that word again. It keeps cropping up in these Revealing Reptile blogs) you can begin to spot subtle differences between individuals in a group or population.

I call this one Donnie Darko. Can you see why?

I have built up a catalogue, over the years, of portraits of adders. These are possibly the easiest to differentiate as their individuality is displayed on the tops of their heads. Each adder is born with a distinguishing head and neck pattern. Just as we have finger prints which set us apart from one another reptiles also bare subtle distinguishable characteristics.

Grass snakes require a different approach. If for some reason you need to tell one from another (for example in a PhD study on individuality in reptiles) you need to look at their throat markings. This is where they have their individuality. The checker-board patterns below a grass snake’s chin and throat are very distinct.

I do know people who have studied grass snake populations and have had to gather the snakes to check each one (The resulting stink from days of being sprayed with musk have resulted in these people becoming disowned by all who know them).

I’m sure their crescents and cheek markings are distinct as well but much more subtly, perhaps.

Two male common lizards both with distinct markings.

Lizards are quite distinctly patterned across their bodies and so a good photograph will allow the observer to tell one from another. Again, patient observation of a group will help build up recognition of individuals. Unlike the snakes the colouration of a lizard does not show through clearly until about the second year. See previous blog ‘Second Year in the life of a Lizard.’

Slowworm female. You’ll need a microscope to tell the difference between these.

So far with slowworms I’ve failed to become adept at telling one from another. They are different, I’m sure, with a few together you can use size and tone of colour. Facial markings are so subtle and fine that you would have to take a good, long, hard look.

Reptile surveying can become all encompassing, your social life may wander. Time spent staring at reptiles is, however, very rewarding in it’s own way. Learning to tell one from another helps us to understand group interactions, dispersal and other behaviours. To quote one of the volunteers who came out recently ‘you have to look and look further.’

Happy Herping!

John Grundy

John has spent more than thirty years honing his skills as a spotter of our region’s elusive and well-camouflaged reptiles. He can often be found wandering the moors of Durham looking for signs of life in the undergrowth. As the Revealing Reptiles Project Officer John frequently delivers reptile survey training to groups and individuals.

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