June 2021

Crocodile bezoar

Is this a dung ball created by a dung beetle?


This round smooth ball does have the general appearance of a dung beetle ball but is in fact a crocodile bezoar or hairball.

Crocodiles have powerful digestive systems to deal with the food they eat, which is mostly whole animals. Most parts of their prey, including bones, are easily broken down by the crocodile’s digestive enzymes. However, the hair and fur, hooves and outer plates of turtle shells, are made of a substance keratin, and this is not easily digested.

They may pass the hair or fur through as a scat, but crocodiles sometimes develop a bezoar or hairball that they regurgitate after eating and digesting animals that have irritating hair, such as wild pigs.

In simple terms the bezoar is solid mass of indigestible material that accumulates in the digestive tract of an animal, sometimes causing a blockage. Bezoars are sometimes mistakenly confused with gastroliths, which are the stones that are swallowed by some animals including crocodiles and alligators, some birds and even some ancient marine reptiles, to help break up and digest food.

Many other animals create bezoars or hairballs in their digestive tracts. Cat owners can be all too familiar with cat hairballs, and even goats can have them. Goat bezoars were prized in medieval medicine for warding off the risk of being poisoned.

Wild pigs often feature on crocodile’s menus. Given that wild pigs destructive foraging and predation on crocodile clutches brings them in close proximity to the water’s edge, it is not surprising, and somehow appropriate, that they end up as meals for crocodiles.

Queensland Museum's Find out about... is proudly supported by the Thyne Reid Foundation and the Tim Fairfax Family Foundation.