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)

A man does physical exercise during sunset over the Finnish Gulf coast in St. Petersburg, Russia, Wednesday, April 14, 2021. (Photo by Dmitri Lovetsky/AP Photo)

Anicka Newell, of Canada, does a handstand ahead of the final of the women's pole vault at the 2020 Summer Olympics, Thursday, August 5, 2021, in Tokyo. (Photo by Matthias Schrader/AP Photo)

A person does a handstand in front of a burning pile of tyres during a protest against prospect of military rule in Khartoum, Sudan on October 21, 2021. (Photo by Mohamed Nureldin Abdallah/Reuters)

Antonina Yermokhina, 86, does physical exercises during her daily training session on the embankment of the Yenisei River in the Siberian town of Divnogorsk, Russia November 13, 2017. (Photo by Ilya Naymushin/Reuters)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

Valeria Ruiz, 10, from Colombia, does a cartwheel while visiting the U.S. Capitol, as Republican members of the House continue to work towards electing a new Speaker of the House in Washington, U.S., October 9, 2023. (Photo by Kevin Lamarque/Reuters)

Olympic gold medal-winning gymnast Hezly Rivera does a flip before throwing out a ceremonial first pitch before a baseball game between the Texas Rangers and the New York Yankees, Wednesday, September 4, 2024, in Arlington, Texas. (Photo by Jeffrey McWhorter/AP Photo)