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Penguins and albatrosses have a ‘touch sensor’ in their beak
Some seabirds might have a ‘sixth sense’ at the end of their beak, new research reveals.
Getting a better understanding of the bill-tip in penguins and albatrosses might provide new ways to protect these threatened birds and better understand how they evolved.
When hunting for prey in the dark waters of the ocean, certain seabirds might have a secret weapon.
A new study has revealed a network of touch-sensitive pits, known as a bill-tip organ, hidden inside the beaks of albatrosses and penguins. While other birds like parrots and ducks are known to use this organ to help handle objects and sense movement, it had never before been detected in seabirds.
In other birds, such as ostriches, this bill-tip organ is an evolutionary relic. But researchers now want to know whether the organ helps penguins and albatrosses to catch food at depth underwater, or woo a mate in their tactile courtship rituals.
As Dr Carla du Toit, the lead author of the research explains, it’s just one of the many things we’re yet to understand about this bird sense.
“While some of the earliest research on bill-tip organs is more than a century old, our understanding of them is still fairly limited,” she says. “We know that various species have this organ, but we don’t have a good idea about how it evolved.”
“Finding these organs in penguins and albatrosses adds another piece to this puzzle. We’re really excited to describe them for the first time, as it represents an important stepping stone in understanding how birds evolved.”
The findings of the research were published in the journal Biology Letters.
If their bill-tip organ is active, it might help to stop albatrosses getting stuck on fishing lines. © stylefoto24/ Shutterstock
What are bill-tip organs used for?
Beaks are much more than a mouth - they’re one of the main ways birds experience the world. All birds get a certain amount of sensation from their beaks, but some species have taken this to extremes with what is called the ‘bill-tip organ’.
Parrots use this extra sense to help them manipulate food and other objects, while ducks can use them to detect food floating in the water. Kiwis and ibises can even use their beaks to sense the vibrations of their prey buried underground.
Until recently, however, no one thought that penguins and albatrosses had a bill-tip organ. That all changed when two scientists working with the Natural History Museum made a chance discovery.
“About eight years ago, Dr Alex Bond and Dr Steve Portugal noticed that there were some unusual structures on the beaks of albatrosses,” Carla recalls. “They reached out to me and my supervisor, Dr Susan Cunningham, and we realised that they could be the sensory pits of a bill-tip organ.”
By scanning samples taken from penguins and albatrosses the team were able to peer inside the beak. The beaks of these birds had structures similar to species known to have a bill-tip organ. This included a high number of canals in the bone, known as the neurovascular foramina, which provide space for nerves.
“This was a really unexpected finding, as penguins and albatrosses aren’t known for using touch to find their prey,” Carla says. “It’s really interesting to speculate about what they might use it for.”
“While we know that these birds can locate their prey visually, they also lose their depth perception and binocular vision at the tip of their beak when they put their heads underwater. The bill-tip organ could help to account for this, providing the tactile stimuli they need to grab and hold their prey when they get closer.”
If penguins and albatrosses do use touch-based foraging, it could change how we protect these endangered animals. One of the main threats to these birds is longline fisheries, as they get attracted by the fishing lures and caught on the lines.
By better understanding how they find food, new tactile countermeasures might help to keep these birds from being killed.
“We also find that a lot of these birds ingest plastic, so it’s possible that tactile stimulation could be making them mistake plastic for food,” Carla adds. “We’ll need to investigate more deeply to see if this is the case.”
The team’s research suggests herons might also have a bill-tip organ. © Richard Sagredo/ Shutterstock
Do other birds have bill-tip organs?
While it is possible that penguins and albatrosses do use their bill-tip organ, behavioural tests and brain studies will be needed to confirm this. But this is more difficult than it might sound.
“Many penguins and albatrosses are threatened with extinction, so it’s difficult to get access to them,” Carla explains. “Bird flu is also an added complication.”
“While we know exactly what part of the brain is involved in sensing stimuli from the bill-tip organ, we can’t look at these tissues because of the risk of infection from accessing specimens. It’s something we hope to pick up on in the future using birds that have died naturally once the avian pandemic is over.”
Instead, the researchers are pushing ahead with investigations of what the bill-tip organ can reveal about the wider evolution of birds. They analysed over 360 species to look for patterns in the sensory pits, finding that birds with the organs tended to have more pits on their upper beak.
“Our analysis included over 80% of living bird families, and it looks like more birds, including herons and gannets, have structures that look like a bill-tip organ,” Carla says. “We’ll now need to do more targeted research to establish whether this is the case.”
