Alex Mustard / Yellowtail tang (Zebrasoma xanthurum) male and female turn belly to belly during spawning to ensure fertilization. Temple, Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea. This action is very fast...

Danny Green / Polar bear (Ursus maritimus) male female pair looking upwards, snow covered hills in background. Svalbard, Norway, April 2018.

Dave Bevan / Slow motion clip of two pairs of Jackdaws (Corvus monedula) squabbling over nest site, Worcestershire, England, UK, May.

Markus Varesvuo / Japanese / Red-crowned crane (Grus japonicus) two calling and dancing, part of bonding and courtship display, Hokkaido Japan February

Sergey Gorshkov / Leopard (Panthera pardus) female fighting off male after he tries to mate with her. Londolozi Private Game Reserve, Sabi Sand Game Reserve, South Africa.

Alex Hyde / Yellow-flecked glassfrogs (Sachatamia albomaculata) mating pair, Osa Peninsula, Costa Rica

Andy Rouse / Great crested grebes (Podiceps cristatus) pair in courtship 'weed dance' in morning light, Wales, UK, February.

Tony Wu / Humpback whales (Megaptera novaeangliae) engaged in courtship, with the male hovering above the female. Vava'u, Tonga, Pacific Ocean.

Danny Green / Atlantic Puffin (Fratercula arctica) pair bill rubbing part of courtship ritual, Skomer Island, Wales, UK, May

Lou Coetzer / Pintailed whydah (Vidua macroura) male displaying to female, Masai Mara, Kenya.

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their courtship dance in which they mimic each other's movements. The Netherlands. April.

Andy Sands / Small emperor moth (Saturnia pavonia) male below female both displaying eyespots on Gorse, Captive, UK, April