vision in the deep sea article

monty

Colossal Squid
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#1
Since there was some interest in this over in supporters, I thought I'd make a thread to discuss this article:

Vision in the Deep Sea by Eric J. Warrant and N. Adam Locket

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=241117

which I've found has a wealth of information about the visual world at depths of interest to deep-sea ceph studies.

I should re-read it myself to comment. If anyone needs the PDF feel free to PM me and I'll send it to you.
 

monty

Colossal Squid
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#2
On re-reading, I still enjoyed the article quite a bit, so I figured I'd bump this thread a bit.

It seems that Architeuthis and other big-eyed cephs are a "best of both worlds" in that their eyes are so big they don't have to sacrifice visual acuity in order to have good low-light vision, unlike a lot of the smaller-eyed animals surveyed in the paper. I'd expect this means the large squids are really visually superior to most of the other animals at the depths where they live, and that combined with the long reach of their tentacles probably means they can ambush prey with a sudden tentacle strike before the prey is aware of their presence.

I also find the concept of polarization being used to break camouflage interesting (p.700) since cephs can discriminate based on polarized light. Also, I learned (p.693) that there are many more cephs that have some color discrimination (or at least more than one receptor type)-- I had previously thought that only Watasenia scintillans had color perception.

Most intriguing, though, I find the picture the authors paint of the diversity of visual environments found in the deep sea, and how it's possible to understand the adaptations of animals based on where in these regions they spend their lives. It's easy to forget that most of our footage of these animals in their native environment is shot from ROVs and submersibles that have huge, bright camera lights, and produce an environment quite different from the natural one.
 

OB

Colossal Squid
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#3
Will commit to reading, also. I owe Eric that...
 

DWhatley

Cthulhu
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#4
monty;143946 said:
Most intriguing, though, I find the picture the authors paint of the diversity of visual environments found in the deep sea, and how it's possible to understand the adaptations of animals based on where in these regions they spend their lives. It's easy to forget that most of our footage of these animals in their native environment is shot from ROVs and submersibles that have huge, bright camera lights, and produce an environment quite different from the natural one.
I wonder how the number of differences compare to the diversity on land. Initially I thought the observed numbers to be huge but then started thinking about insects and other non-mammals and realized that I had no idea if the number of variations on land were more or less than in the sea.
 

Rachael

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#5
This paper is very interesting. I did not know about the other species of cephalopod, apart from W. scintillans, that have more than one visual pigment (Japetella sp, Pyroteuthis sp, Pterigioteuthis sp, and Bathyteuthis). I was wondering have all these species evolved the same ability to have more than one visual pigment independently or are they related to each other in some way?
 

monty

Colossal Squid
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#6
Rachael;144983 said:
This paper is very interesting. I did not know about the other species of cephalopod, apart from W. scintillans, that have more than one visual pigment (Japetella sp, Pyroteuthis sp, Pterigioteuthis sp, and Bathyteuthis). I was wondering have all these species evolved the same ability to have more than one visual pigment independently or are they related to each other in some way?
That's a very interesting question... I wish I had time to poke around the web for more info... From a quick glance at tolweb.org, it doesn't seem like Japetella (an octopod) and Bathyteuthis are too closely related to the others, so my first guess would be that it's a pretty easy adaptation to get via a copy-and-mutate pathway, but that's pure conjecture. If you find any more information, please post about it!

edit: Nixon & Young don't describe multiple visual pigments in any species other than W. scintillans, for what that's worth.
 

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