Nav: Home

How do fishes perceive their environment?

May 03, 2017

Fishes perceive changes in water currents caused by prey, conspecifics and predators using their lateral line. The tiny sensors of this organ also allow them to navigate reliably. However, with increasing current velocities, the background signal also increases. Scientists at the University of Bonn have now created a realistic, three-dimensional model of a fish for the first time and have simulated the precise current conditions. The virtual calculations show that particular anatomical adaptations minimize background noise. The results are now being presented in the Journal of the Royal Society Interface.

The ide (Leuciscus idus) is a fish that inhabits the lower stretches of slow-flowing rivers. Like most fishes, it can perceive the current using its lateral line. The mechanoreceptors of this organ are distributed over the surface of the entire body, which is why the organ provides a three-dimensional image of the hydrodynamic conditions. Fishes can thus also find their way around themselves in the dark and identify prey, conspecifics, or predators. The recently retired zoologist Prof. Horst Bleckmann from the University of Bonn has spent many years researching the sensitive organ and has used it as inspiration for technical flow sensors in order to, for instance, identify leakages in water pipes.

First realistic three-dimensional computer model

The scientists Dr. Hendrik Herzog from the Institute of Zoology and Dr. Alexander Ziegler from the Institute of Evolutionary Biology and Ecology at the University of Bonn have now entered a new dimension of research into the lateral line in fish: they created the first realistic, three-dimensional computer model of the lateral line system, which they used to calculate the precise flow conditions of the surrounding water. "We concentrated on the head of the ide, because the lateral line of the fish has a particularly complex form there," reports Dr. Herzog.

This organ has two different types of sensors. Some protrude like small bumps from the surface of the fish's skin and the water flows directly over them. Others sit in canals that are submerged into the cranial bone and are connected to the water via small pores. "If prey, such as a freshwater shrimp, is close by, the local water current and pressure conditions change," explains Dr. Ziegler. The fish registers this with its many sensors. "However, until now, the actual function of such different types of current measurement had not been clarified conclusively."

Both researchers received active support from Birgit Klein from the Westphalian University of Applied Sciences. In her bachelor thesis at the Institute of Zoology, the current master student compared various methods of 3D reconstruction. She took around 350 photos of the head of the ide from various angles and used them to produce a 3D model of the fish surface. She had dyed the channels and sensors of the lateral line beforehand, which is why the structures in the model can be clearly identified. She then optimized the dataset by digitizing the fish head using a much higher-resolution laser scanning procedure.

This created a realistic image of the fish surface, but the inside of the animal was not recorded in this way. This is why the researchers used a micro-computed tomography scanner as the third method. A contrast agent allowed the soft tissue to be shown even when using this X-ray technique. At the end, data from all three techniques flowed into the realistic model of the lateral line. The zoologists thus simulated various current conditions and calculated the hydrodynamic signals to the various sensors.

A strong current is a challenge for the fish, as the background noise for the sensors is particularly great. Nevertheless, the fish can precisely perceive its environment even with high water speeds. As the researchers show with their calculations, depressions ensure that the current is significantly reduced for the bump-like sensors that sit on the surface of the skin. "The relative signal strength of, for instance, prey organisms thus becomes greater," explains Dr. Herzog. For the sensors in the channels, it was shown that certain sections of the lateral line are particularly sensitive to the respective current strength due to different channel diameters.

Bio-inspired application: improved navigation of underwater robots

"Using our methodical approach, comparative anatomical studies between different fish species with an especially high level of detail will be possible in the future," reports Dr. Ziegler. His colleague sees bio-inspired applications in the foreground: "The knowledge from such 3D models of fish may also make it possible to significantly improve the autonomous navigation of underwater robots using flow sensors," suggests Dr. Herzog.
-end-
Publication: Form and function of the teleost lateral line revealed using three-dimensional imaging and computational fluid dynamics, the Journal of the Royal Society Interface, DOI: http://dx.doi.org/10.1098/rsif.2016.0898

Media contact:

Dr. Hendrik Herzog
Institute of Zoology
University of Bonn
Tel. +49 (0)228/735490
E-mail: hendrik.herzog@uni-bonn.de

Dr. Alexander Ziegler
Institute of Evolutionary Biology and Ecology
University of Bonn
Tel. +49 (0)228/735758
E-mail: aziegler@evolution.uni-bonn.de

University of Bonn

Related Sensors Articles:

Sensors detect disease markers in breath
A small, thin square of an organic plastic that can detect disease markers in breath or toxins in a building's air could soon be the basis of portable, disposable sensor devices.
Are your sensors spying on you?
Cyber experts at Newcastle University, UK, have revealed the ease with which malicious websites and installed apps can spy on us using just the information from the motion sensors in our mobile phones.
A novel method for the fabrication of active-matrix 3-D pressure sensors
A new study, affiliated with South Korea's Ulsan National Institute of Science and Technology (UNIST), developed a transistor-type active-matrix pressure sensor using foldable substrate and air-dielectric layer.
For female mosquitoes, two sets of odor sensors are better than one
A team of Vanderbilt biologists has found that the malaria mosquito has a second complete set of odor receptors that are specially tuned to human scents.
Optimized sensors to study learning and memory
Scientists at Max Planck Florida Institute for Neuroscience are working to understand how molecules send messages throughout the neuron.
Pioneering chip extends sensors' battery life
A low-cost chip that enables batteries in sensors to last longer, in some cases by over ten times, has been developed by engineers from the University of Bristol.
New sensors can detect single protein molecules
For the first time, MIT engineers have designed sensors that can detect single protein molecules as they are secreted by cells.
Contracts signed for ELT mirrors and sensors
At a ceremony today at ESO's Headquarters four contracts were signed for major components of the Extremely Large Telescope (ELT) that ESO is building.
Pain sensors specialized for specific sensations
Many pain-sensing nerves in the body are thought to respond to all types of 'painful events', but new UCL research in mice reveals that in fact most are specialized to respond to specific types such as heat, cold or mechanical pain.
3-D-printed organ-on-a-chip with integrated sensors
Researchers have made the first entirely 3-D-printed organ-on-a-chip with integrated sensing.

Related Sensors Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".