ZSL London Zoo is undertaking its annual weighing day, with staff finding novel ways to take the measurements of some weird and wonderful creatures.
So, how do you measure a gorilla? Try tucking some tasty treats into a tree next to the measuring stick, then retreat to a safe distance! (see video)
Figures are recorded into the Zoological Information Management System (ZIMS), a database shared with zoos around the world, helping zoo-keepers to compare information on thousands of endangered species.
Luke Harding, a qualified keeper in the reptile department, was tasked with weighing an "incredibly rare" species of crocodile that was hatched at the zoo in June. "At this age these guys are really secretive feeders, so as babies they're really shy. So one of the best ways for us to tell that everybody within the group is eating well and growing well is to take regular weights," he said.