The slimy blue sacks, which resemble a half-deflated balloon, were found over the weekend on the beach at Grève d’Azette.
The creatures, whose Latin name is Velella velella, are harmless drifters which have no form of self-propulsion and rely on the wind and their translucent sail. They usually live on the surface of the sea out in the Atlantic but can get stranded in large numbers around the Channel Islands and the UK following a prolonged period of westerly winds.
The majority of by-the-wind sailors, which are floating colonies of hydrozoans, are ‘left handed’, with the sail going from upper-left to lower-right along their long body axis. This feature – whether they are right- or left-handed – can dictate where they are distributed.
Paul Chambers, marine and coastal manager at Environment, Growth and Housing, said: ‘The last time this happened they were found in their hundreds along the south and west coasts and eventually made their way around the rest of the coast.’
By-the-wind sailors resemble the more exotic Portuguese man o’ war, which washed up in their hundreds two years ago. However, they lack the bright pink and purple sail – and potentially deadly sting – which their more fearsome-sounding lookalike possesses.
