If you’re planning on a summer paddle or swim in British sea watch out for these stinging stunners.

It’s prime jellyfish season and while the majority found in our waters are relatively harmless there are a couple you should avoid.

The lion’s mane jellyfish, which has been spotted this year around Scottish and Northern Irish waters, packs a nasty sting, although it’s unlikely to do you any real damage.

The jellyfish that you really want to avoid however, is the infamous Portuguese man o’ war.

This specimen, which can grow to 30m, delivers an extremely painful and occasionally fatal sting.

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Thankfully, they’re pretty rare in our water and restricted to the South West, although large numbers were reported in the late summers of 2007, 2008 and 2009.

Other jellyfish with powerful stings include the mauve stinger which is occasionally seen in western waters.

The most common jellyfish in British waters are the barrel, blue, compass, moon and ‘by-the-wind sailor’ jellyfish – although their stings are mild.

If you do spot a jellyfish, particularly one of the rarer or more painful variety, you can report them to The Marine Conservation Society at www.mcsuk.org .

Just don’t touch it!