Bioluminescent Deep Sea Critters

[Sean Hayden]

What's that about? There are several animals with this ability that spend their entire lives in total darkness. Why did they evolve this trick?

[Svartalf]

anybody who could bring a satisfactory answer to that would be up for a nobel prize

[JimC]

Mating signals are one clear possibility...

[Sean Hayden]

Yes, and to attract a meal. But the question is why evolve these strategies in a completely dark environment?

[Svartalf]

well, it's surprising, but it's been verified that the visual organs of deep sea creatures are not at all atrophied, so, strategies involving light and visibility are not so absurd as it may seem, though, in a fish eat fish environment, signalling one's presence to potential predators may seem a bit counterproductive...

[Sean Hayden]

Most are blind though. Still, why should anything rely on light in a completely dark environment?

Is the thinking just that they brought the sensory gear with them to the depths?

[JimC]

Most are blind though. Still, why should anything rely on light in a completely dark environment?

Is the thinking just that they brought the sensory gear with them to the depths?

Cave fish have become blind over many generations - in total darkness, there is no selective pressure to maintain functioning eyes.

However, many deep-sea creatures can migrate up and down (often on a day/night cycle), and eyes can still be useful in very dim light. As for bioluminescence, it is a symbiotic relationship with light emitting bacteria. You asked "why evolve these strategies in a completely dark environment?" - well, it couldn't evolve where bright light swamped the relatively weak signals, so it has to be in darkness. Terrestrial insects such as glow worms (actually beetle larvae) exist in caves, and fire flies do their mating dance at night. Perhaps it hasn't evolved in cave fish, once their eyes have atrophied...

And I suspect that light signalling between conspecifics (mostly for mating) evolved first, which then provided a niche for deceptive advertising to attract unwitting prey, who thought they had a chance for a quick fuck...

[Sean Hayden]

Do all deep-sea creatures who use light migrate up and down?

it couldn't evolve where bright light swamped the relatively weak signals, so it has to be in darkness.

The question is more to do with the necessity of exposure to light to evolve the benefits of sight and light signaling. You seem to acknowledge this next when you talk about terrestrial insects which live in both light and dark.

They can't explain why animals that spend their entire lives in darkness have evolved these strategies.

--//--

On fucking, I just read something truly horrifying.

The female anglerfish releases pheromones to attract tiny males. When a male finds her, he bites on to her and never lets go. When a male of the anglerfish species Haplophryne mollis bites into the skin of a female, he releases an enzyme that digests the skin of his mouth and her body, fusing the pair to the point where the two circulatory systems join up. The male then atrophies into nothing more than a pair of gonads.

[JimC]

...The male then atrophies into nothing more than a pair of gonads...

Bollocks!

Sean Hayden wrote:

The question is more to do with the necessity of exposure to light to evolve the benefits of sight and light signaling. You seem to acknowledge this next when you talk about terrestrial insects which live in both light and dark.

They can't explain why animals that spend their entire lives in darkness have evolved these strategies.

The interesting counter-example is the various examples of blind cave fish (mostly totally separate lineages, so convergent evolution). As far as I know, none of them use bioluminescence. There are 2 possible reasons:

1. The sight atrophy evolved first, so making bioluminescent displays would be pointless.
2. Their cave environments had no light-generating bacteria for them to co-opt.

In contrast, the material I've seen and read about deep-sea fish don't seem to indicate much in the way of sight atrophy. Now, in some cases that may be, as I suggested earlier, that they are involved in vertical migrations, and their eyes are still useful in regions of very dim light. However, there is another possibility; once bioluminescent displays evolved in the aphotic zone, there was selective pressure to maintain eyes to monitor the displays around them, which would give important information about dangers or potential food.

[Sean Hayden]

Yeah, that makes sense; they took it down with them. I may search the library databases for more later.

[Sean Hayden]

. Their cave environments had no light-generating bacteria for them to co-opt.

Apparently some of the fish have their own systems that don't rely on a relationship with bacteria.

[laklak]

Yes, and to attract a meal. But the question is why evolve these strategies in a completely dark environment?

Ain't no why, shit just happened. Some shit was good, some shit wasn't, sucked if your shit was part of the wasn't.

Hard to fathom, actually, but a shiiiiiiiitload of time went by. How many tens and hundreds and thousands of thousands of generations does it take until some mutant deepsea mofo mutates a bioluminiscent thingy and attracts a bunch more brine shrimp? Short jump to us, if you think about it.

[Sean Hayden]

Yar, according to one study I found fish began evolving the ability during the Cretaceous some 150 mya. More than half of the species evolved to do so without the aid of bacteria.

Of course on a planet where bugs fart fire I guess a little light in your ass ain't too surprising.

[rainbow]

What's that about? There are several animals with this ability that spend their entire lives in total darkness. Why did they evolve this trick?

It is part of the Good Lord's plan.

[rainbow]

Of course in Africa, we go one better:
https://www.discovermagazine.com/planet ... llion-isns