Five destructive invasive species are described in more detail below: killer shrimp, floating pennywort, zebra mussel, water primrose and quagga mussel. You can read descriptions of their identifying features and follow the links to identification sheets with photos.
For other invasive species, use the links below to download identification sheets, and to see pictures and videos.
If you come across an invasive species, you should report it using this link:
One of the most invasive species in Europe, the killer shrimp can survive for up to 15 days in damp conditions. It kills a range of British species, including young fish, and can spread rapidly. It is a freshwater species, but can survive in brackish waters too.
A few tips for identifying killer shrimps:
If you spot a killer shrimp, you should report it:
This is also called 'water pennywort' or sometimes just 'pennywort'. It has shiny, kidney-shaped leaves with crinkled edges and is usually found floating on still or slow-moving fresh water. Floating pennywort can grow up to 20 centimetres a day, blocking out light and reducing the oxygen for other plants and animals.
If you spot a floating pennywort, you should report it:
Zebra mussels are found in rivers, canals and lakes and can block pipe-work and affect lock gates. They can also smother native species and rapidly take nutrients from the water, altering ecosystems.
If you spot a zebra mussel, you should report it:
Water primrose is a highly invasive freshwater weed from South America. It has become a serious problem in France where it blocks water ways and overgrows ponds and lakes. It has only recently started to be found in Britain. but if it were to establish widely could cost as much as £242 million to manage. You should therefore make sure to report any sightings as soon as possible using the links below.
If you spot a water primrose, you should report it:
Closely related and very similar to the zebra mussel, but possibly even more invasive. It can survive in some places that zebra mussel can't and can even displace them. Like the zebra mussel and killer shrimp this species comes from the ponto-caspian region in south-east Europe. It's not yet present in Great Britain, but like the killer shrimp could turn up soon. Any suspected sighting should be reported as soon as possible using the guidance below.
Similar to zebra mussel and quite difficult to distinguish, if you suspect quagga mussel make sure to make a note of where you saw it and inform the relevant organisation (the Environment Agency in England and Wales, the Scottish Environment Protection Agency in Scotland).
Image courtesy of Mike Quigley, U.S. Department of Commerce
If you spot a Quagga Mussel, you should report it: