Touch sensation by pectoral fins of Pimelodus pictus

[Silurus]

Hardy, AR, BM Steinworth & ME Hale, 2016. Touch sensation by pectoral fins of the catfish Pimelodus pictus. Proceedings of the Royal Society of London B: Biological Sciences. doi: 10.1098/rspb.2015.2652

Abstract

Mechanosensation is fundamental to many tetrapod limb functions, yet it remains largely uninvestigated in the paired fins of fishes, limb homologues. Here we examine whether membranous fins may function as passive structures for touch sensation. We investigate the pectoral fins of the pictus catfish (Pimelodus pictus), a species that lives in close association with the benthic substrate and whose fins are positioned near its ventral margin. Kinematic analysis shows that the pectoral fins are held partially protracted during routine forward swimming and do not appear to generate propulsive force. Immunohistochemistry reveals that the fins are highly innervated, and we observe putative mechanoreceptors at nerve fibre endings. To test for the ability to sense mechanical perturbations, activity of fin ray nerve fibres was recorded in response to touch and bend stimulation. Both pressure and light surface brushing generated afferent nerve activity. Fin ray nerves also respond to bending of the rays. These data demonstrate for the first time that membranous fins can function as passive mechanosensors. We suggest that touch-sensitive fins may be widespread in fishes that maintain a close association with the bottom substrate.

[smitty]

What exactly are mechanosensors. Could not find anything in dictionary.com and does the fin cause a reaction to humans. I have touched my Pimelodus and did not get any reaction.

[bekateen]

A mechanosensor is the same thing as a mechanoreceptor: It means a cell or structure (in this case, in the skin) which can detect and respond to mechanical stimuli - touch, pressure, friction, pulling, shearing sensations.

It means basically that the fish can "feel" things with it's fins.

Cheers, Eric

[smitty]

bekateen is it a myth that they can cause human to have an adverse chemical reaction?

[bekateen]

bekateen is it a myth that they can cause human to have an adverse chemical reaction?

Hi Smitty,
I think you are asking whether or not the fish spines can sting or cause us harm, yes? If that's your question, then the answer is yes. Here is another thread on that subject: Pathophysiological effects of Pimelodus maculatus venom.

But from the abstract, that isn't the focus of the paper in this current thread.

Cheers, Eric

[bekateen]

Hi @Silurus,

Do you have access to this article? If so, could I please have a copy (my institution doesn't appear to have access)? My email is [email protected].

Thank you, Eric

[bekateen]

Here we examine whether membranous fins may function as passive structures for touch sensation... To test for the ability to sense mechanical perturbations, activity of fin ray nerve fibres was recorded in response to touch and bend stimulation. Both pressure and light surface brushing generated afferent nerve activity. Fin ray nerves also respond to bending of the rays. These data demonstrate for the first time that membranous fins can function as passive mechanosensors.

This sounds like a nice piece of work.

It would make sense that membranous fins should possess inherent sensory ability - Wouldn't you expect that fish can "feel it" when something touches their fins? And it shouldn't be a requirement that the sensors are physically located in the actual membrane, but they could be located along the rays; as long as the location of the sensor is mechanically perturbed by an action (sensory stimulus), even if the perturbation is applied elsewhere on the fin, this should be sufficient to trigger a neural signal to the central nervous system. Much in the same way that hitting below your kneecap with a rubber hammer activates stretch receptors in the muscle spindles of the thigh to trigger the knee-jerk reflex, the force is pulled through the tissue from the source of contact to the site of the sensory receptor.

Cheers, Eric

[smitty]

@betateen I know they probably can cause discomfort by sticking you. Maybe not as bad as some thorny cats. But I heard that they can cause a chemical reaction.

[bekateen]

Hi Smitty, I'm not sure then what you mean by "chemical reaction." The link above mentions venom in the fish fin, so it's not just the discomfort of a physical poke that we would feel. There is a negative reaction (pain, inflammation, cardiac harm), and it's triggered by chemicals (venom).

What have you read/heard before?

Cheers, Eric

[pleconut]

I have kept a small group of these only for the last few weeks, so I have been reading this with some interest, as it does seem in my observations that they do seem to interact with one another, and even other fish using fin contact. The second point re toxicity, as I'm still unfamiliar with them to a point, I'm slightly extra careful working in and around them. I've read elsewhere a jab can hurt for a upto a good few hours. And one reason why catching them with a net isn't recommended, not only can it injure them, but they can potentially injure you while you try to free them from the net.

[smitty]

@bekateen: Okay you answered it I guess I missed it when I read it earlier. So they do cause some form of chemical reaction if they stick you. I got stuck but did not get a reaction so I was thinking it was a myth. Thanks for educating me.