Scorpions, tough Chelicerata arachnids, well known for their association with the one of the most hostile, hottest environments on earth…deserts. But even when not living in deserts, scorpions still tend to be found in warm ecosystems, such as rainforests and savannas. However, believe it or not, there is a scorpion that braces the rather unpleasant British weather.
The European yellow-tailed scorpion (Euscorpius flavicaudis), is a small black scorpion with yellow-brown legs, that is widely distributed across Europe (especially in the south), as well as Northern parts of Africa (Cloudsley-Thompson and Constantinou, 1983). As an adult, they reach sizes of 35-45mm in length, in shape it is a typical fossorial scorpion with large, strong pedipalps, a stout body, short legs and a short, thick tail (Benton, 1991). It is also known to be a very docile species, only resorting to stinging when actively provoked, preferring to scuttle away than waste its venom on something that it cannot eat. However, if the scorpion does sting, it’s venom is very mild and essentially harmless (Wanless, 1977). This small, discrete scorpion has been residing in the UK for quite some time now, with the earliest record coming from 1870, identified by JJ Walker (the labeled specimen is currently in the Natural History museum). This first specimen was found at the Sheerness Dockyards in Kent, and it is here where these scorpions mainly survive. However, there have been other records of this species from places such as the Plymouth docks. It is therefore, safe to assume that E. flavicaudis was accidentally introduced by hitting a ride on ships coming over to Britain from Europe, but the fact that they have managed to survive here, is a true testament to the adaptability of scorpions.
Despite being well known for living in some of the hottest places on earth, these environments are often very cold at night therefore scorpions, like most desert creatures, often stay hidden during the day (normally in a burrow) and venture out at night. By this point they have absorbed enough warmth from the sand during the day to be active during the cool hours of the night. Furthermore, many places where scorpions are common (such as Arizona) can experience quite cold winters, during which many species of scorpions hibernate. However, what is considered cold in Arizona and Britain, are two very different things. The upper boundary of winter temperatures in Arizona (especially in the Southern and Central areas) can be between 18°C and 21°, to put that in perspective, the average temperature for the UK in July (our hottest month) is 19°C . So, whilst the American scorpions experience blistering hot summers and mild winters, over in the UK the weather remains consistently mild. Furthermore, the areas normally inhabited by E. flavicaudis (such as southern France and Spain) also experience significantly hotter summers and milder winters than England. So, how do they survive?
The populations of E. flavicaudis are restricted to these dockland areas in the South of England, which implies that they did come across on boats from Europe. However, the fact that they have not spread so far shows that they are still surviving in the mildest and warmest areas of the UK. It has been suggested that E. flavicaudis may have developed different behaviors that have enabled them to survive for so long in the cold UK climate. For example, Cloudsley-Thompson and Constantinou (1983), tested to see whether the UK population of E. flavicaudis, had adapted to a more daily lifestyle to make use of the daytime warmth. Diurnal activity is not unheard of in scorpions, but is more common in forest species, with desert scorpions tending to be more dedicated to the nocturnal lifestyle (Cloudsley-Thompson and Constantinou, 1983).
However, their study found no significant increase in diurnal activity in the scorpions at the Sheerness Docks, but they are not strictly nocturnal, like most desert scorpions, and do show some degree of daytime behavior. Therefore, they concluded that these scorpions invoke no special behavioral or physiological changes to survive in England. Most scorpions are capable of surviving freezing temperatures and E. flavicaudis are found at high altitudes in the alps, so must encounter cold temperatures. In the UK, their activity levels are very low, with each individual on average, only leaving their wall crack retreats around 10 times a year (Benton, 1992). Like most scorpions, they are ambush predators, therefore minimizing the amount that they need to move, they simply sit and wait for a meal to stumble into their path. In the UK they feed mainly on woodlice but will occasionally each one another if food is in low supply (Benton, 1992), furthermore they can last an incredibly long time between meals. Scorpions are well known for their ability to survive long periods of food deprivation, with one individual of Urodacus manicatus (black rock scorpion) survived 17 months on a single house fly meal (Southcott, 1995). This ability to survive harsh conditions is how scorpions have lasted millennia and inhabit some of the toughest places on Earth.
As global warming continues, and average temperatures are on the rise, it is as fully as possible that the UK is residing E. flavicaudis may start spreading and moving further inland and could potentially inhabit much of England. As for now, they are restricted to the low rainfall, warmer docklands, but it is entirely plausible that one day they may become an integral part of the UK’s ecosystem, which in itself could cause problems. Accidentally introduced species are famed for the disruption that they so often cause. However, some slots into the ecosystem without any apparent negative effects, for example the tube-web spider (Segestria Florentina) was accidentally introduced to the UK in a similar manner to E. flavicaudis, way back in the 1800s. And whilst still restricted to the Southern areas, populations of S. florentina are steadily increasing and spreading further North, they have become well established and thrive in their new environment (we almost went a whole blog post without mentioning a spider). But for now, the UK’s only scorpion is stuck in the immediate areas from which they were disembarked from the boats. I very much wish to go and find one at some point, with a UV torch during the summer months, they shouldn’t be too hard to find at night. It would be exciting to see a scorpion in England.
To conclude, the Euscorpius flavicaudis scorpions that brace the grim English climate, don’t appear to possess any special attributes that enable them to do this. But instead, just rely on the tough, robustness of their Scorpion nature. By moving very little, eating very little and simply sitting and waiting for their food to appear, they are managing to survive, in a small restricted population, despite the unpleasant climate. However, given enough time and significant rises in temperatures, they could one day spread and become integrated into the UK’s ecosystems.
I hope you have enjoyed reading this quick article on Euscorpius flavicaudis and its life in the UK, was about the time I did an article that wasn’t about spiders.
Thank you for reading!
Until next time.
Photo credit: Jan Ove Rein, scorpion files.
Benton, TG (1992). The ecology of the scorpion Euscorpius flavicaudis in England. Journal of Zoology, 226(3), 351-68.
Cloudsley-Thompson, JL and Constantinou, C. (1983). How does the scorpion Euscorpius flavicaudis manage to survive in Britain? International Journal of Biometeorology, 27(2), 87-92.
Southcott, RV (1955). Some observations on the biology, including mating and other behavior, of the Australian scorpion Urodacus manicatus Pocock. Transactions o the Royal Society of South Australia, 78145-54.
Wanless, FR (1977). On the occurrence of the scorpion Euscorpius flavicaudis (Degeer) at Sheerness Port, Isle of Sheppey, Kent. Bull. Brother arachnol. Soc., 4(2), 74-6