With its huge eyes, comical name and diminutive size, Mark R. Smith’s image of a baby Hawaiian bobtail squid can’t help but raise a smile. A curiously endearing creature, the cephalopod is just 1.5cm across, its mantle cavity bearing more than a passing resemblance to a rather natty shower cap. But it is also a beautiful example of symbiosis – nature’s version of “I’ll scratch your back if you scratch mine” – for on the underside of the squid is a light organ which houses bioluminescent bacteria. The squid offers the bacteria protection and food, while the bacteria emit a glow – a handy trait that the squid uses to offset its silhouette, helping it to evade predators in the depths below. Mark R. Smith’s entry combines several images of a Hawaiian bobtail squid with different focus lengths to create a final picture with greater depth of field than normal. (Photo by Mark R. Smith/Wellcome Images/Macroscopic Solutions)

An Indian labourer sifts coloured powder, known as “gulal”, to be used during the forthcoming spring festival of Holi, inside a factory at Fulbari village on the outskirts of Siliguri on March 6, 2017. Holi, the popular Hindu spring festival of colours is observed in India at the end of the winter season on the last full moon of the lunar month, and will be celebrated on March 13 this year. (Photo by Diptendu Dutta/AFP Photo)

A dancer prays before she performs as land activists gather to commemorate the upcoming Women's Day in Phnom Penh, Cambodia, March 7, 2017. (Photo by Samrang Pring/Reuters)

Omsin, a 25 year old femal green sea turtle, rests next to a tray of coins that were removed from her stomach after a surgical operation at the Faculty of Veterinary Science, Chulalongkorn University in Bangkok, Thailand, March 6, 2017. (Photo by Athit Perawongmetha/Reuters)

Shot by Bert Hardy, the black and white images show prisoners carrying out remedial tasks such as untying knots in post office string and sewing mail bags. Other intriguing shots show lags doing their daily one hour outdoor exercise, being frisked for contraband items by officers during a routine “rub down” and serving evening meals. Strangeways was designed by Alfred Waterhouse and cost £170,000 ($207,910) to build. The prison, famed for its prominent ventilation tower and imposing design, has become a local landmark. Here: A prison officer frisking prisoners during the “rub-down” at Strangeways Prison in Manchester, UK on November 1948. (Photo by Bert Hardy/Picture Post/Hulton Archive/Getty Images)

Melissa Stewart's team competes in the official restart of the Iditarod, a nearly 1,000 mile (1,610 km) sled dog race across the Alaskan wilderness, in Fairbanks, Alaska, U.S. March 6, 2017. (Photo by Nathaniel Wilder/Reuters)

Cairo-based artist Chanel Arif's paints for her art project called After Dinner that uses humans and their surroundings as her canvas, in her gallery in the capital of Cairo, Egypt March 2, 2017. (Photo by Sherif Fahmy/Reuters)

(L-R) Marisa Berenson, Caroline de Maigret, Nicki Minaj and Lou Doillon attend the Haider Ackermann show as part of the Paris Fashion Week Womenswear Fall/Winter 2017/2018 on March 4, 2017 in Paris, France. (Photo by Bertrand Rindoff Petroff/Getty Images)