Cuttlefish bone found on a beach in Torquay, Victoria
Image: Julia Cock
Source: Julia Cock
Question: Who killed this cuttlefish? And how did they do it?
Answer: This cuttlefish bone was found on a beach in Torquay, Victoria. The "bone" was examined by Museum Victoria's Marine Invertebrate Curators who identified that the teeth marks were made by a Bottlenose Dolphin.
Cuttlefish are not easy prey – they squirt clouds of dark ink at their attackers. This "smokescreen" gives cuttlefish a chance to escape and also warns nearby cuttlefish that a predator is in their midst. Cuttlefish ink is also thought to cause digestive problems for dolphins.
Scientists have long-known that Bottlenose Dolphins feed on cuttlefish, but recently Museum Victoria scientists found out how. It's a complex and fascinating process.
Marine Biologists Dr Julian Finn and Dr Mark Norman have discovered that dolphins are meticulous sushi chefs. Once a dolphin has caught and killed a cuttlefish, it lifts the cuttlefish up in the water and repeatedly smashes it with its snout. This ruptures the ink sac, resulting in an explosion of ink.
Once the dolphin has shaken all the ink from the cuttlefish, it moves it down to the ocean floor, turns the cuttle upside-down and pushes it across the sand. This strips the thin skin on the back of the cuttlefish, causing the cuttlebone to pop out intact and leaving behind a delicious ink- and bone-free sushi meal.
In the past, scientists had observed whole cuttlebones bobbing to the surface above feeding dolphins. How they were extracted intact was a mystery, until now.