Cubans gather at Havanas Malecon waterfront to watch the fireworks on the eve of the city's 500th anniversary on November 15, 2019, in Havana, Cuba. The fireworks were launched from the opposite side of the Havana bay, at the El Morro fortress and lighthouse complex. (Photo by Sven Creutzmann/Mambo photo/Getty Images)

A camel calf is seen among a herd in the desert near Dakhla in Morocco-administered Western Sahara, on October 13, 2019. In the Oued Eddahab desert in Western Sahara, Habiboullah Dlimi raises dairy and racing camels just like his ancestors used to, but with a little help from modern technology. While his animals roam free and are milked traditionally, by hand, at dawn and dusk, they are watched over by hired herders and Dlimi follows GPS coordinates across the desert in a 4X4 vehicle to reach them. (Photo by Fadel Senna/AFP Photo)

A Sadhu or a Hindu holy man carrying his pet monkey walks after taking a dip at the confluence of the river Ganges and the Bay of Bengal on the occasion of “Makar Sankranti” festival at Sagar Island, south of Kolkata, India, January 14, 2017. (Photo by Rupak De Chowdhuri/Reuters)

A walker has left a handprint on a snow- covered tree trunk on Grosser Feldberg mountain in the Taunus mountain range, Germany, 16 January 2017. (Photo by Frank Rumpenhorst/DPA)

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)

Martin Herrera, 58, who has had a love for roosters since his childhood, and has spent the last 20 years domesticating and training them, walks with his favorite rooster “Paquito” in San Jose, Costa Rica April 27, 2017. (Photo by Juan Carlos Ulate/Reuters)

People walk along the Neva River at sunset in St.Petersburg, Russia, Tuesday, December 6, 2016. The temperature in St.Petersburg is –9C ( 15.8 °F). (Photo by Dmitri Lovetsky/AP Photo)

An air tanker drops fire retardant on flames as firefighters continue to battle against the Detwiler fire in Mariposa, California on July 19, 2017. The Detwiler fire is currently at 7 percent containment and has burned more than 45,000 acres and destroyed eight structures. (Photo by Josh Edelson/AFP Photo)