The lateral line – my superpower

Hi there! For this post, I want to talk about dancing. That’s right folks, I perform a little dance when I’m trying to get Toni or the other ladies to hang out with me. I also do this move called a “lateral display” where I make myself look really big and shake my body at other males to threaten them. When I fight with other males, we push around a lot of water at each other. If we can’t resolve our fight with these behaviors, then we go to the more dangerous behaviors, like biting each other.

See fish have this thing called the mechanosensory lateral line. It’s composed of these little bundles, called neuromasts, that are on my skin or inside canals beneath my skin. These neuromasts have little hair cells on them that are covered by a jelly-like mass called the cupula. When something near me moves in the water, it creates water motion that deflects the cupula over these neuromasts and opens mechanically gated ion channels on the hair cells. This information then gets sent to my brain. This water-movement information helps me orient in a current, find things to eat, avoid things trying to eat me, and even communicate with my friends (and enemies!).

My humans are interested in how I use this sensory system for social communication. To look at my lateral line system, they placed me in a container of orange stuff they called DASPEI. This dye stains the hair cells of my neuromasts and makes them glow in the dark! Here’s a picture…. Think I’ll just use this as my Halloween costume this year!

They can also make my lateral line non-functional. They place me in a beaker of chemicals, either cobalt chloride or aminoglycoside antibiotics, for a few hours. This chemically disables my neuromasts. It’s a weird feeling. I can still feel it if they touch me, but I can’t feel any of the water movements from the other fish around me. Anyways, after this treatment, they let me recover overnight. Then they let me do my thing! I either get to court Toni or defend my territory from another dude. The humans then compare my behaviors when I have an intact functioning lateral line to when they’ve ablated it.

They found that when they knock out my lateral line, I have a hard time assessing the other male. Sure, I can see how big he is, but when we’re closely size-matched, that water movement information also helps me. Because we can’t feel the water we’re trying to push at each other without this functioning lateral line, we also escalate our fights a lot quicker. Man, that’s tiring! I’m happy I normally have use of my lateral line so I don’t have to do that all the time… They even looked in my brain to see where this information is processed!

Now my humans are trying to determine how we use our lateral line during reproduction. As I said, I perform a little dance called a “quiver” when courting Toni. My humans think that Toni uses the water information produced by this dance to help decide which male she wants (obviously I’m the only correct choice!). So they’re knocking out her lateral line system and seeing what it does to her receptiveness to me. I really hope my dancing still impresses her… Check back later to hear from Toni and how this impacts her!


Want to know more about the lateral line? Check out these papers from the Maruska lab:

Butler, J.M. and K.P. Maruska. 2016. Mechanosensory signaling as a potential mode of communication during social interactions in fishes. Invited Commentary, J Exp Biol 219: 2781-2789. link

Butler, J.M. and K.P. Maruska. 2016. The mechanosensory lateral line system mediates activation of socially-relevant brain regions during territorial interactions. Front Behav Neurosci 10:93. link

Butler, J.M. and K.P. Maruska. 2015. The mechanosensory lateral line is used to assess opponents and mediate aggressive behaviors during territorial interactions in an African cichlid fish. J Exp Biol. 218: 3284-3294. link

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