Fish Hunting Strategies

[gwand]

Fish species evolved different hunting strategies using distinct visual cues

Researchers have described how fish larvae rely on species-specific combinations of vision and movement to detect and capture prey.

phys.org

 

[GaryE]

The tail spring thing is fascinating.

I once set up a tank that was 2/3 filled. Up at the top, I attached a culture medium for wingless fruit flies, which dropped into the tank and formed herds on the duckweed, which covered half the surface.
My wild caught Epiplatys phoeniceps got impatient, and started picking off flies 3 or 4 inches above the water, on the outside of the culture container where the wingless mutants would crawl around. The 'pike killies' would drift and watch, clearly calculating. Then the tail would curl and fire them at the target, which once they had had a few missed attempts, they never missed again.

That tail curl generated explosive speed.

In the wild, I caught Epiplatys huberi under overhanging plants. When I pulled the net out of the tangles, I found fish, but also a lot of tiny spiders, and ants. My weird experiment in (unsuccessfuly) trying to breed E. phoeniceps years before, by giving them all the bugs they could eat had let me see natural hunting behaviour, as I'm sure the fish I caught were feeding on out of water foods.

 

[TwoTankAmin]

I was a psych major in College. Part of that involved Experimental Psychology and experimental design. Unlike many of the other sciences, psychology relies on less objective factors and more on subjective ones. Especially challenging in experimental research in this field involves trying to eliminate the uncontrolled variables which might be involved.

So, when I read research papers in other fields, especially those relevant to our hobby, I am always looking for the failure to consider what I believe are variable not eliminated which are likely influencing the results. After reading what was available at the above link and Then skimming through the actual paper. I had a few issues. Perhaps the most important was the lack of a section normally found in research papers called "MATERIALS AND METHODS" This elucidate how they studied and what they used to do so.

As far as I can tell the purpose of the "paper" was to understand the hunting strategies of several different species which they use in the wild. And the first alarm bell went off when I read this"

We used high-speed cameras and deep-learning-based tracking tools to record and analyze thousands of hunting episodes from individual fish larvae placed in controlled environments with live prey,"

This study was not conducted in the wild. The live prey part made sense but the controlled environment was off base. Fish do not live and involved naturally in controlled environments. These most definitely have an important influence on both evolution and the behaviour it engenders in species.

The next issue I had was that there was no identification of what constituted the live prey. If I have to find and kill a cow and then carve it up to make my steak dinner v.s. going to the supermarket and buying it, my behaviors will be completely different.

Next, prey does not swim around with a big sign on it that says eat me I will make it easy for you to do so. Prey have also evolved to avoid becoming food to the best of their ability to do so. Their environment plays a part in this aspect of things. If the prey ia always caught, that species is likely to have gone extinct long ago and the hunter would either have had to switch prey or also gone axtinct from starvation.

I have never studied the behavior in the wild of the fish I have kept in my tanks. For this information I have relied on the work of others and conversations with people who have actually studied the fish I the wild. What I do know is that how the fish behave in our tanks is, in many case, not identical to how they behave in the wild.

Because of my interest in the plecos and especially in the B&W Hypancistrus of the Big Bend region of the Rio Xingu, I have kept and bred a number of these species in my tanks for years. I cannot recreate their natural environment, I cannot even get it close. I do not feed them the foods on which they rely in the wild. I breed them in species tanks with no predators. About the best I can do is keep them in parameters that are similar to those in the wild and insure their nutritional needs are met from the foods I do feed.

What the above as done is is allowed me to become decently informed about how my fish behave in captivity and what methodologies I can use which will not discourage nor to prevent them from spawning. What I cannot learn from this is how they behave in the wild without any controlls being im[osed by me.

I am pretty sure the researchers in the paper referenced could not have done their work in the wild. It could only be done in an artificial setting in a lab which is a whole lot smaller and much more limited than what the fish encounter in nature. So the eye movements can be studied and can be explained, but why they are that way cannot be. The fish evolved in nature not confined in tanks.

I will end this with an observation. A good portion of humanity is able to read and write. Everybody reading this thread reads from left to right. But ask if you ask Google "is all modern writing left to right" here is what comes back from the AI Overview

No, not all modern writing is left to right. While many European, North American, South American, Indian, and Southeast Asian languages use left-to-right scripts, languages like Arabic, Hebrew, Urdu, and Persian are written from right to left. There are also languages like Mongolian, Chinese, and Japanese which are traditionally written vertically from top to bottom, although they can also be written horizontally (left-to-right).

The directionality of a writing system is a fascinating aspect of linguistics and cultural history. It's thought to have been influenced by factors such as the materials used for writing (e.g., stone, paper) and even the handedness of the scribes.

So, how many of us reading this thread can read from right to left of from top to bottom?

I would also ask this question about the research. Why was it done besides to satisfy the curiosity of the researchers who like to study this sort of thing? The conclusions are pretty much that all the fish studied catch their prey using different specific methods physiologically and thus manage to feed themselves. I also wonder what might eat the hunters and it this has an influence on things.