Hindu devotees take part in the religious festival of Holi, also known as the festival of colours, in the town of Barsana in the Uttar Pradesh region of India, March 16, 2016. (Photo by Cathal McNaughton/Reuters)

A schoolgirl collects rubbish from Karachi's Clifton beach early morning April 22, 2013, during a cleaning campaign as part of the commemoration of Earth Day. (Photo by Akhtar Soomro/Reuters)

Riot police detain a woman during a protest near Mong Kok police station in Hong Kong, China on September 7, 2019. (Photo by Tyrone Siu/Reuters)

Amanda Seyfried attends the premiere of 20th Century Fox's “The Art Of Racing In The Rain” at El Capitan Theatre on August 01, 2019 in Los Angeles, California. (Photo by Phillip Faraone/Getty Images)

A fishmonger carries a shark on his motorcycle in Padang, West Sumatra, Indonesia August 25, 2016. (Photo by Iggoy el Fitra/Reuters/Antara Foto)

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)

Combat between two male stag beetles, Italy, 2022. During the mating season, male stag beetles (Lucanus cervus) go into a frenzy, with lively but harmless clashes, in which bigger males often have the advantage over smaller ones due to their impressive mandibles. Longer larval development and genetic traits can increase the size of some individuals, but all saproxylic beetles are threatened by poor forest management, logging and dead wood removal to “clean” the forest. (Photo by Iacopo Nerozzi)

An urban Opossum covered in light snow visits a suburban Chicago deck on December 10, 2025. (Photo by H Rick Bamman/ZUMA Press Wire/Rex Features/Shutterstock)