The six-months-old female koala cub holds on to the back of zoo keeper Lena at the zoo in Duisburg, Germany, 23 October 2015. The yet unnamed baby weighs 580 grams. (Photo by Roland Weihrauch/EPA)

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)

Israeli soldiers of the Search and Rescue brigade take part in a training session in Ben Shemen forest, near the city of Modi'in May 23, 2016. (Photo by Amir Cohen/Reuters)

Veterinarians and biologists from the Quito Zoo and the Andean Condor Foundation fit a tracking collar that juvenile Andean bear Tupak will wear for the next four years, prior to his reintroduction into the wild, after the bear's life was deemed in danger due to proximity to humans, in Quito, Ecuador on March 31, 2024. (Photo by Karen Toro/Reuters)

A girl competes during a Hobby horsing competition in St. Petersburg, Russia, on Sunday, April 21, 2024. Several dozen kids, 48 girls and one boy, from first-graders to teenagers gathered in a gymnasium in northern St. Petersburg, Russia's second largest city, for a hobby horsing competition. (Photo by Dmitri Lovetsky/AP Photo)

American rapper Ashnikko poses as she arrives for the Brit Awards at the O2 Arena in London, Britain on February 11, 2023. (Photo by Maja Smiejkowska/Reuters)

“Atzeries”, a fire beast sets off his fire crackers during a “Correfocs” in Barcelona's Gracia neighborhood, Spain on May 27, 2023. (Photo by Matthias Oesterle/Alamy Live News)

“Sunward”. When the Mediterrenean Mantis opened its wings, It seemed very impressive at the sunshine... Photo location: Nicosia, Cyprus. (Photo and caption by Hasan Baglar/National Geographic Photo Contest)