The most colossal cephalopod you’ll find in the ocean is the giant squid: The animal can grow up to 43 feet in length and weigh a quarter of a ton. Despite their size, giant squids are notoriously difficult to spot. They’ve only been filmed alive a couple of times, which means that marine biologists have to get creative when estimating the species’ population size.

In the Science Friday video below, Elizabeth Shea, curator of mollusks at the Delaware Museum of Natural History, explains how sperm whale stomachs provide the best evidence of giant squid numbers we have. Architeuthis dux is one of the whale’s favorite meals, and their durable beaks can be found in whale stomachs long after the rest of their bodies have been digested.

Based on the number of beaks collected from the digestive tracks of sperm whales, scientists estimate that there are around 4.3 million giant squids inhabiting the depths of the oceans. That may seem high, but estimates can go much higher: Some calculations put the maximum number of giant squids at 130 million. So while the footage we have now may be scarce, there could be many chances to capture the squids in their natural habitat in the future.

[h/t Science Friday ]