Jellyfish in the North Atlantic - in pictures

Pelagia noctiluca. Doggett and Shucksmith headed to the outlying islands of North Rona and Sula Sgeir, some 85 miles west of Stromness. The water was full of jellyfish and other planktonic creatures at many of the sites they visited. The further they headed offshore, the more bizarre these globular lifeforms became Photograph: Matt Doggett /www.earthinfocus.com

Neoturris pileata. These medusoid lifeforms came in all shapes and sizes, with vivid colours and fine details Photograph: Polly Whyte/www.earthinfocus.com

The highlight of all the species for the two divers was Pelagia noctiluca, a stunning, delicate, mauve jellyfish. It was this species that was the subject of Shucksmith's winning entry to the British Wildlife Photography awards in 2011. 'These are truly stunning creatures, their vivid purple and lilac hues complemented by graceful, long, stinging tentacles extending out into the oceanic waters. They may pack a bit of a sting but their tentacles attract many small fish seeking refuge from hungry predators' Photograph: Richard Shucksmith/www.earthinfocus.com

An unknown species Photograph: Matt Doggett/www.earthinfocus.com

Photographing Neoturris pileata Photograph: Matt Doggett/www.earthinfocus.com

In a year when many blooms of jellyfish have been reported around the British Isles, salps were also abundant. Salps are colonial sea squirts that are linked end-to-end. They swim through the water column, filtering their food through inhalant and exhalent siphons. Despite their appearances, salps are some of the most evolutionary advanced creatures in the sea, falling just short of the vertebrates on the tree of life Photograph: Matt Doggett/www.earthinfocus.com

Close inspection of the Thetys vagina salp reveals its intricate structure. Thetys can grow up to 30cm long and are a good indication that the oceanic water being dived is being moved by oceanic Atlantic currents Photograph: Richard Shucksmith/www.earthinfocus.com

Elsewhere in Scotland, Doggett and his wife experienced another dense plankton bloom closer to home. The waters of Loch Duich on the west coast provided perfect conditions to support an awe-inspiring aggregation of Aurelia aurita, the moon jelly. 'The jellies were so dense that at times I couldn’t see my wife Polly just a few metres away. It was a very calming, surreal experience, like diving in some kind of thick, primordial soup' Photograph: Matt Doggett/www.earthinfocus.com

Smaller jellyfish included comb jellies (ctenophores) such as Beroe cucumis, that swim by using the fine hairs called cilia along the length of their body. These are predatory animals, engulfing any planktonic life unfortunate enough to get in their way Photograph: Matt Doggett/www.earthinfocus.com

Smaller still are the ctenophores Lampea sp. that cruise the water column hunting salps. A close-up reveals tiny bright-orange shrimps called amphipods that are hitching a ride on the jellyfish Photograph: Richard Shucksmith / www.earthinfocus.com

The two marine biologists and photographers were aboard the MV Halton to document the clear blue waters and abundant wildlife of the North Atlantic, but little did they realise how much the plankton would compete for their attention Photograph: Matt Doggett/www.earthinfocus.com