A woman dressed up for Halloween travels on a Metro train in São Paulo, Brazil on October 30, 2017. (Photo by Cris Faga/Rex Features/Shutterstock)

Local residents crowd a swimming pool during a hot weather in Suining, Sichuan province, 27 July 2008. (Photo by Reuters/Stringer)

A tree stands in a lake in Usingen near Frankfurt, Germany, Wednesday, March 22, 2023, the World Water Day. World Water Day was established in 1992 by the United Nations to spread awareness about the water condition all over the world. (Photo by Michael Probst/AP Photo)

A Hindu devotee takes sand bath at Sangam, the confluence of the rivers Ganges and Yamuna, in Prayagraj, in the northern Indian state of Uttar Pradesh, Monday, June 5, 2023. Prayagraj in the northern Uttar Pradesh state is an important Hindu pilgrimage center. (Photo by Rajesh Kumar Singh/AP Photo)

Harvesting water lilies in Dhaka, Bangladesh in the last decade of August 2023. (Photo by Mostafijur Rahman Nasim/Solent News & Photo Agency)

A child dressed in a Santa Claus costume reacts, on the day Palestinian Christians attend an Orthodox Christmas Mass at the Greek Orthodox Saint Porphyrius Church, amid the ongoing conflict between Israel and Hamas, in Gaza City on January 7, 2025. (Photo by Dawoud Abu Alkas/Reuters)

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)

Japan's delegation gather to sign the formal surrender document on the U.S. Navy battleship USS Missouri in Tokyo Bay in a September 2, 1945 file photo. (Photo by Reuters/US Navy)