Catfish use complex coordination to suck in prey

April 16, 2019

PROVIDENCE, R.I. [Brown University] -- Catfish do not have arms or tongues to help them catch and swallow their prey -- instead, a catfish ready to strike moves its head.

Using a powerful X-ray-based technology, Brown University scientists tracked catfish as they caught and swallowed prey to develop a precise understanding of the complex set of motions required to create the suction necessary to eat. They found that many of the bones in the catfish skull work in a coordinated manner to catch food. However, the bones move more independently when the fish swallow.

"Fish have the most mobile skulls of vertebrates," said Aaron Olsen, a postdoctoral research associate in Brown's Department of Ecology and Evolutionary Biology. "Fish have over a dozen moving pieces in their skull, and they're all connected together by joints and ligaments in these closed loops called 'linkages' in engineering. In comparison, humans have moving lower jaws and middle ear bones, but that's it. The heads of fishes also have very diverse shapes, so we can study how these complex systems evolved in lots of different linages of fishes."

The findings were published on Wednesday, April 17, in the journal Proceedings of the Royal Society B.

To make the observations, Olsen and his colleagues used a 3D-imaging technology called X-ray Reconstruction of Moving Morphology (XROMM), which was developed at Brown. The technology combines CT scans of a skeleton with high-speed X-ray video, aided by tiny implanted metal markers, to create visualizations of how bones and muscles move inside humans and animals. The technique is so precise that scientists can track movements with errors equivalent to only the width of a human hair.

"XROMM basically gives us X-ray vision to watch how multiple bones move within an animal as they perform a behavior," Olsen said.

In this study, the team used XROMM to watch three catfish catch and swallow prey -- including food pellets, bits of squid and earthworms. First, the fish move their whisker-like barbels back and forth in the tank. Immediately after a barbel touches a piece of food, four primary bones that surround the mouth and throat expand outward in a consistent and coordinated manner to form the suction necessary to catch it.

On the other hand, these bones move more independently and less consistently as the fish swallow. Olsen isn't certain why swallowing is less coordinated.

"It seems like different tasks need different levels of coordination," Olsen said. "But what determines a good level of coordination for a specific task is an open question. What our study shows is that these natural behaviors have different levels of coordination. We're not sure if they strictly require different levels of coordination."

Previous research from the lab of Brown professor and senior researcher Elizabeth Brainerd has used XROMM to study the feeding behavior of other fish, including bass and sharks. Largemouth bass protrude their jaws, which helps to catch their prey. Catfish cannot protrude their jaws in that manner, Olsen said. Instead, the bone critical for that action in bass evolved into the base of the whisker-like barbels in catfish, he added.

Bamboo sharks are distantly related to all bony fish, including catfish. However, both bamboo sharks and catfish have powerful shoulders, or pectoral girdles, that both species move extensively during feeding, Olsen said.

Comparing different species of fish with different body shapes, skull structures and feeding behaviors can provide insights into how fish with different body shapes evolved different structures and mechanisms to solve similar tasks, Olsen said.

Members of the research team are currently using XROMM to track the characteristic "vacuum-like" behavior of koi. Other members of the Brainerd lab are studying the feeding behaviors of other species of fish.

Olsen is in the process of constructing a model to explain how the bones and ligaments that comprise the catfish skull move together as a complex system.
-end-
In addition to Olsen and Brainerd, other authors include Ariel Camp from Brown and Patricia Hernández from George Washington University. The National Science Foundation (grants 1612230, 1655756 and 1661129) and the Bushnell Research and Education Fund supported the research.

Brown University

Related Behavior Articles from Brightsurf:

Variety in the migratory behavior of blackcaps
The birds have variable migration strategies.

Fishing for a theory of emergent behavior
Researchers at the University of Tsukuba quantified the collective action of small schools of fish using information theory.

How synaptic changes translate to behavior changes
Learning changes behavior by altering many connections between brain cells in a variety of ways all at the same time, according to a study of sea slugs recently published in JNeurosci.

I won't have what he's having: The brain and socially motivated behavior
Monkeys devalue rewards when they anticipate that another monkey will get them instead.

Unlocking animal behavior through motion
Using physics to study different types of animal motion, such as burrowing worms or flying flocks, can reveal how animals behave in different settings.

AI to help monitor behavior
Algorithms based on artificial intelligence do better at supporting educational and clinical decision-making, according to a new study.

Increasing opportunities for sustainable behavior
To mitigate climate change and safeguard ecosystems, we need to make drastic changes in our consumption and transport behaviors.

Predicting a protein's behavior from its appearance
Researchers at EPFL have developed a new way to predict a protein's interactions with other proteins and biomolecules, and its biochemical activity, merely by observing its surface.

Spirituality affects the behavior of mortgagers
According to Olga Miroshnichenko, a Sc.D in Economics, and a Professor at the Department of Economics and Finance, Tyumen State University, morals affect the thinking of mortgage payers and help them avoid past due payments.

Asking if behavior can be changed on climate crisis
One of the more complex problems facing social psychologists today is whether any intervention can move people to change their behavior about climate change and protecting the environment for the sake of future generations.

Read More: Behavior News and Behavior Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.