The UK’s deadliest wildlife

The UK is not renowned for being a particularly dangerous country, especially when it comes to its wildlife. However there are a select few organisms that can still be described as deadly, whether it is to humans or other organisms. The term deadly is obviously subjective, so the organisms on this list are determined as such by both their potential and realised danger to both humans and other wildlife.

The first entry we have comes in plant form. The Aconitum plant genus, also known as Devil’s Helmet, Wolfsbane, Monkshood and the Queen of Poisons (an impressive title to be sure), is found to grow in many gardens in the UK. Fatalities are not common, but are documented. Part of the buttercup family, and comprised of roughly 250 species, the most poisonous part of the plant is the roots, which if ingested can cause death in just a few hours. Violent vomiting and diarrhoea are usually followed by death by heart failure. The leaves are less toxic than the roots, but can still cause strong stomach upsets. So take care if you are planning on picking your own salad.

Next we have something more sizeable and unexpected. The killer whale (Orcinus orca), also known as the orca, belies its name by being the largest member of the dolphin family, not whale. Weighing up to 6.5 tonnes, these apex predators are not know to attack humans. They do however pose a threat to several aquatic organisms, including seals, sealions, seabirds and even other whales. Armed with teeth up to 4 inches long and the ability to echolocate their prey, they possess a ferocious arsenal, which coupled with their speed and power makes them extremely well adapted predators.

With a name alone that can instill fear, the Portuguese man o’war (Physalia physalis) will be familiar to many, but not by association to our quaint little island. Occasional visitors to the south coast, the Portugues man o’war is not a jellyfish, or even a single organism, but in fact a collection of polyps which together comprise an animal known as a siphonphore. Stings are rarely fatal, but are reported to be extremely painful. The tentacles can also sting after the organism has died and washed up on a beach!
portuguese man of war

Finally we end on a familiar face. The adder (Vipera berus), one of only 2 species of snake to survive in Britain, does contain enough venom to kill a human (although unlikely in a healthy adult), but there has not been a reported death from a bite since 1975. This is down to a combination of advances in antivenom, a reticence for the animal to bite unless threatened, and declining numbers due to habitat destruction.

Although there are certainly many countries that contain more dangerous wildlife than the UK, wherever life exists, threat exists with it.


BBC News, (2014). How dangerous is Devil’s Helmet?. [online] Available at: [Accessed 28 Jan. 2015]., (2015). Adder. [online] Available at: [Accessed 1 Feb. 2015].

National Geographic, (2015). Killer Whales (Orcas), Killer Whale Pictures, Killer Whale Facts – National Geographic. [online] Available at: [Accessed 28 Jan. 2015].

National Geographic, (2015). Portuguese Man-of-Wars, Portuguese Man-of-War Pictures, Portuguese Man-of-War Facts – National Geographic. [online] Available at: [Accessed 28 Jan. 2015].

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Jamie Graham

Jamie Graham

I have recently completed my Master's in Biodiversity, Evolution and Conservation at UCL. I have a passion for nature and enjoy writing!
Jamie Graham

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