Whipsnade Zoo carried out its annual weigh-in for all of its 3,500 animals, a huge-scale operation to keep track of the health and wellbeing of all creatures great and small.
All animals must have their vital statistics recorded as a part of this regular check-up. The weights and measurements are recorded in a database called Zoological Information Management System (ZIMS), which helps zookeepers around the world compare important information on thousands of species.
This global database is used by more than 1,000 zoos, with information on 6.8 million animals across 21,000 species, and is constantly growing.
Zoological manager Matthew Webb said: "All of our animals at ZSL Whipsnade Zoo are weighed and measured regularly, but the annual weigh-in is an opportunity to review the information we've recorded, and ensure it is up-to-date and accurate."
The waist measurements and weight checks are particularly important to help identify pregnant animals, many of which are from endangered species.
Whipsnade Zoo is part of the European Endangered Species Programme, and so it is critical that pregnancies are identified among the animals during the weigh-in.
The animals at Whipsnade range greatly in size, weight and height, and the zookeepers must use creative tactics to coax the animals onto the scales.
Greater one-horned rhinoceros Behan, one of the heaviest animals at the zoo, stepped onto an industrial-sized scale for keepers to record her weight, which came to an impressive 1765kg.
The European brown bears were encouraged with veggie rewards to stand at their full height, which was measured at 2.1 metres. Northern rockhopper penguins were tempted onto the scales by their favourite fishy snacks, and weighed in at only 2.68kg.
As one of the world's most endangered species of spider, the zoo's baby Desertas wolf spiderling required particularly sensitive equipment in order to weigh in at just 0.039g.
The zoo's new aquarium presented another challenge for keepers who had to zip up their wetsuits and dive into the water in order to measure the 300 underwater inhabitants in 10 different aquatic habitats.
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