Franco Banfi / Freshwater jellyfish (Craspedacusta sowerbii) Lake Lugano, Ticino, Switzerland. August. Invasive species.

Jordi Chias / Atolla jellyfish (Atolla wyvillei) with Gentoo penguin (Pygoscelis papua) in the background near the surface. Antarctic Peninsula. Finalist in the Underwater category of the Wildlife Photographer of t...

Solvin Zankl / Deepsea Octopus (Bathypolypus bairdii) specimen from the North Atlantic, near the Faroe Islands at a depth of 805m

Solvin Zankl / Portuguese man-of-war (Physalia physalis) colony, underwater Sargasso Sea, Bermuda

Solvin Zankl / By-the-wind sailor (Velella velella) colony. Sargasso Sea, Bermuda.

Solvin Zankl / Portuguese Man-of-War (Physalia physalis) close up of tentacles, Sargasso Sea, Bermuda

Gabriel Rojo / Close up of Passionflower (Passiflora caerulea) La Pampa, Argentina.

Alex Hyde / Chlorophyte or green alga (Volvox aureus) in pond water. UK. The larger spheres are approximately 0.5mm in diameter. Digital composite image.

Alex Hyde / Harvestman (Megabunus diadema) with prominent, spiky eyes, Peak District National Park, Derbyshire, UK. April

Jack Dykinga / Saguaro cactus (Carnegiea gigantea) in flower at night, with The Milky Way behind, Sonoran Desert National Monument, Sierra Estrella Mountain Wilderness, Arizona, USA, May.

Juergen Freund / Bigfin reef squid (Sepioteuthis lessoniana) blurred motion photograph, Kimbe Bay, West New Britain, Papua New Guinea.

Juergen Freund / Detail of Giant kelp (Macrocystis pyrifera) gas-filled bladders (pneumatocysts) Vancouver Island, British Columbia, Vancouver Island, Canada.