Incredible! Unique Fish Communicate With Electricity, With Human-Like Cues

Persistent chatter isn't the best way to pass your message across. Taking a breath before speaking about something crucial can make people pay attention more closely to what you have to say.

(Photo : Harrison Haines)

Freshwater Fish Speak Through Weak Pulses of Electricity 

This is not just a trick we humans have puzzled out. Birds and Frogs have also been found to take deliberate pauses in their speech, and as it turns out, elephantfish, or mormyrid fish, usually time their silence almost in the same ways.

These freshwater fish speak through weak pulses of electricity underwater, and a new study has discovered the information they relay to each other is also marked by pauses that are well-timed.

When kept in pairs, mormyrids (Brienomyrus brachyistius) actively make pauses in their electric signals before sending a burst of electric pulses out. When separated from each other, they do this far less often, which proposes it's a characteristic of mormyrid communication.

Such moments of silence that are well-timed are believed to stop fish close by from becoming so used to the frequent stream of electric signals that they no longer really pay attention to what's being said. Rather, a pause of around one second may prime a fellow mormyrid to receive potential messages.

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The Pregnant Pauses 

 The authors wrote: "Our discovery that burst displays tend to happen not too long after pauses in mormyrids is similar to the discovery that human speakers tend to place pauses before words that have high information content."

This isn't the first time mormyrids have been found taking pregnant pauses while electric communication is going on. In fact, other electric fish, known as gymnotiformes have also been found to do the same during courtship. That said, this new research is the first to suggest a cellular model that might give an explanation about these pauses.

Making use of intracellular recording, researchers discovered the brains of mormyrids are more stimulated easily following a short bout of silence. By artificially inserting pauses into the electric signals of a single fish in a pair, the authors were able to reveal a boost in the brain activity of the other fish.

(Photo : Gilberto Olimpio)

Synaptic Depression 

"Interestingly," the team notes, "the suitable timescales for pauses in human speech are approximately almost the same as those in the electric communication of mormyrids, taking place in the range of hundreds of milliseconds to seconds."

This proposes similar cellular process is taking place in both fish and human brains, and the authors believe they know what it is.

When receptors in the brain are continuously stimulated, synapses are known to weaken after a while, reducing the activity of sensory circuits overall. This is referred to as synaptic depression, and it's what permits the animal brain to master which signals are most crucial and therefore require attention the most. 

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