After the rains at the beginning of April, the heat is settling in more each day. Here in Toulouse, the city has already taken on a summer-like appearance. It regularly reaches over 20°C during the day, flowers are blooming on every corner, and people are wearing light clothes instead of the winter coats, already stored away until the next cold season.
A nocturnal and urban huntress
In the evening, the streets are lively with laughter and the clinking of glasses on the terrace. Other animals are also active. Insects that were previously discreet are now coming out again and enjoying the warmth. Our heroine of the day, in fact, loves this warmth. And with the return of mild evening temperatures, there is a good chance we might come across her in the middle of a hunt. Let’s meet at 10 p.m. on Impasse de la Colombette. It’s right in the center, not far from the Jean Jaurès metro station, where brick and asphalt reign. But here, everything is peaceful. Large stretches of vegetation cling to the Toulouse red brick, framing the welcoming terrace of the scientific café nestled at the back of the dead end.
And then, there is a halogen lamp, which with its soft light illuminates the now deserted small courtyard. The obsessed midges circle around it, sometimes joined by some larger night butterflies. A feast is on the horizon for… But yes! There she is! Our huntress is out. Motionless, belly pressed against the wall, she is very close to the circle of light from the lamp. Do you see her? It’s a small lizard from the gecko family, called a Moorish wall gecko, with the scientific name Tarentola mauritanica. Its name evokes its original habitat, Mauritania, an ancient Berber kingdom consisting of several human tribes, with its headquarters located in present-day northern Morocco. As for the word “tarente,” it is more mysterious. Some believe it refers to a certain_SYMBOL_HERETypes of spiders, called tarantulas, whose bite was considered venomous, just like our gecko. But that’s not true! While tarantulas are indeed a threat to the insects and spiders they feed on, they do not produce venom!
## A Stocky and Rough Gecko!
The individual gracing us with its presence tonight is already quite large. About a foot in length from the tip of its nose to the end of its tail. In fact, its tail is as long as its body! The largest individuals can measure up to 15 cm, while babies that have just hatched are less than a centimeter long, so cute! However, I don’t know if it’s a male or a female… The differences are minimal; sometimes you can see a small bump at the base of the tail in males, but from this distance, it’s impossible to know!
Unlike the wall lizard with a elongated body and nose, and covered in smooth scales, our gecko is stocky and has a rough appearance like a little knight in armor. In English, it is sometimes called the “crocodile gecko.” Impressive, right! Its body is covered with small soft spikes, and under its skin, hard plates called osteoderms reinforce its protection, much like its giant cousin, the Komodo dragon, which I have already mentioned in a previous episode. As for its color, it allows it to blend in with rocks and walls where it roams. Therefore, geckos can vary in color from light beige to dark brown, almost black, with or without spots. They can also adjust their color according to the heat: light at night, they adopt a darker color during the day to better absorb the sunlight. Since they depend on the external temperature, they need to warm up well to be active!
## Sticky Fingers and Detachable Tail
Our scaly huntress has other peculiarities. Look at her eyes. In bright light, like tonight around this lamp, her pupil, the black part of her eye, narrows to a very fine vertical slit! In the dark, on the other hand, it widens and rounds, like a cat’s, to capture as much.The Curious World of the Tarentes
Tarentes, those small Mediterranean wall geckos, have some fascinating characteristics. First, their eyes don’t blink! They don’t have movable eyelids like humans. Instead, they use their tongue to moisten their eyes when needed. Additionally, if you look closely at their tails, you’ll notice something interesting. About halfway down the tail, the rough scales disappear, indicating that this part of the tail has regrown after being shed. This defense mechanism helps them escape from predators as the detached tail continues to wriggle, creating a distraction. Fortunately, through successive skin changes, their tails regenerate.
Tarentes can live up to 10 years if they avoid falling prey to predators, especially domestic cats. Sacrificing a piece of their tail is a small price to pay for a long life. But that’s not their only superpower! These geckos can effortlessly climb vertical surfaces due to adhesive pads on their toes that act like suction cups, allowing them to climb, wander, and run at high speeds on walls.
Tarentes Have Enemies in Their Scent!
Tarentes are territorial creatures who don’t appreciate encountering other geckos in their space. They use their sense of smell to detect intruders. If they sense a rival, they quickly extend their tongue to smell the air and identify the intruder’s scent. Recent studies on geckos have shown that they can differentiate between their own scent and that of an unfamiliar gecko. They use this ability to recognize and distinguish between themselves and others, showing a level of self-awareness uncommon in reptiles.
These geckos are known to chase away intruders, as seen when a smaller gecko attempted to approach a light source to catch insects. The larger gecko swiftly signaled the unwelcome visitor to leave with a quick head movement.
Great Travelers… Sometimes Unintentionally!
Although tarentes prefer dry, rocky habitats, they can unintentionally hitch rides to new locations.Tarentes from Mauritania are increasingly found in our cities, where they can find food, warmth, and shelter, whether it’s to lay their eggs in a wall crevice or to rest during the day, well hidden behind shutters. Even though coexisting with humans, especially their playful pets like overly curious cats, has consequences on the tarentes, they are not threatened. On the contrary, it seems that they are expanding their territory: our little lizards are venturing out into the world!
Originally, the Mauritian Tarente was only found along the Mediterranean coast: in North Africa, southern Greece and Italy, as well as southeastern France, where it has been seen since the early 19th century. This region of the world has always been a crossroads, an important trading hub where people and goods move around a lot. It is believed that in part, the tarente arrived in our midst for the first time by being transported on ships. But they continue to travel with the flow of our exchanges. Today, they can even be found in Mexico, Argentina, Uruguay, and in the southern United States, in California and Florida! They are far from their original Mediterranean habitat!
**Track the Tarentes Too!**
In recent years, more and more tarentes have been moving northward. Our small creatures seem to be thriving! In mainland France, the tarente has become a regular sight on the streets of Toulouse, and they are increasingly seen scurrying on walls in Bordeaux and Lyon. A study initiated in 2021 by several scientists from the Evolution and Biological Diversity laboratory at the University of Toulouse, including researcher Jessica Côte, aimed to determine how far the tarente could be spotted in our territory. This “participative” science project is open to everyone, and you too can help the scientists with their research.
To join the study, all you need to do is answer the online questionnaire, which you can find on the website named GeckoLocalisation, and indicate whether or not you have seen a tarente at your place. The initial results show that some tarentes have been spotted as far as Saint-Malo, and even in Lille and Calais, all the way up North near Belgium! The challenge now is to untangle all this and try to understand how they got there. When some individuals are seen alone, far from others, it is likely they were accidentally transported during the shipment of goods. Tarentes hide well, and while hunting for insects, they can easily end up in crates of fruits and vegetables… Further south, in the northern part of Lot, for example, the results suggest that the tarente is moving north on its own, without being transported by humans, as it finds the suitable conditions of warmth, shelter, and food there.
**Geographic Shift Due to Climate Change**
This phenomenon has already been observed in other lizards and snakes, which heavily rely on external temperatures to live their lives. Although they are not cold-blooded as commonly believed, they cannot regulate their body temperature like mammals and birds. As you may have noticed, generally, you feel warmer in summer and colder in winter, but your body temperature remains constant.relatively constant, between 36.6 and 38 °C. Tough! We say we are endotherms, a word that means we can generate and control heat inside our bodies. While reptiles, on the other hand, are ectotherms. Their internal temperature depends directly on the external temperature. That’s why you’ll regularly see lizards basking in the sun: they’re stocking up on energy! If it’s cold, however, they’ll struggle to warm up and generally stay hidden and still. With climate change, Northern Europe is warming up. Winters are milder, summers are hotter, and our geckos are finding new places to settle!
It also seems that the spread of the Moorish gecko is at the expense of other geckos. For example, the European leaf-toed gecko, which was very easily observable in 2009, has become much rarer in 2017, 8 years later. The opposite trend is observed in the Moorish gecko, which is now much more widespread than it was in 2009. So how can we explain the disappearance of one, and the expansion of the other? Does the Moorish gecko adapt better to the city and temperature changes than the leaf-toed gecko? Or does the Moorish gecko, being larger, steal its shelters and food from other geckos? It is still unknown… but scientists are on the case and looking for answers! In the meantime, the Moorish gecko has bright days ahead!