The setting sun illuminates the sky behind wind turbines of a wind park near Neusiedl am See, December 22, 2014. (Photo by Heinz-Peter Bader/Reuters)

The sun rises over the north sea as The Couple by artist Sean Henery sits just of the coast at Newbiggin-by-the-Sea, England, Wednesday October 8, 2014. (Photo by Owen Humphreys/AP Photo/PA Wire)

5-year-old Rina Kumari rubs her eye while cracking stones on the banks of Mahananda river in Siliguri, northeast India, March 5, 2005. Over 400 million people in India live below the internationally agreed poverty line (living on less than US $1 per day). According to estimates, several hundred thousand children work as labourers and beg on the streets in India. (Photo by Desmond Boylan/Reuters)

India: A sweeper cleans the side of a road near a replica of the Eiffel Tower amid heavy fog in the early morning in the northern Indian city of Chandigarh January 18, 2010. (Photo by Ajay Verma/Reuters)

Interior designer Zahra Afridi (R) kicks a punching bag during a kickboxing training session at her home in Islamabad February 10, 2014. Afridi runs her own interior design company. Her most recent project was a Classic Rock Coffee cafe in Islamabad. Though instability continues to plague Pakistan and many areas are dominated by social conservatism, some of the country's more affluent residents have worked to fashion a very different kind of lifestyle for themselves. Pictures of men and women taking part in all sorts of activities and professions – from being a pilates instructor, to a textile retail entrepreneur, to a member of a rock band – offer a different view of Pakistan to images of conflict that often make the news. (Photo by Zohra Bensemra/Reuters)

People take pictures of deer in the Phoenix Park in Dublin, Ireland December 5, 2016. (Photo by Clodagh Kilcoyne/Reuters)

Fr. Denis Crosby blesses a live lamb during a Pattern Day mass to St. Brigid at the holy well of St. Brigid in Liscannor, Ireland February 1, 2017. (Photo by Clodagh Kilcoyne/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)