Showing Pigmentation Changes With Light Exposure in the Cephalopods

Showing Pigmentation Changes With Light Exposure in the Cephalopods

Blue Light Turns an Octopus Red
http://news.sciencemag.org/sciencenow/2011/11/scienceshot-blue-light-turns-an...

One thousand meters under the sea, where the red wavelength of sunlight doesn't penetrate, red organisms are effectively invisible. But things are trickier in the middle ocean depths, between 600 and 1000 meters, where sunlight can still reveal the silhouettes of colorful sea creatures. So a couple of mid-ocean-dwelling cephalopods—the animal class including octopuses and squids—have come up with a flexible strategy: Start out transparent, but change colors when certain predators come around. In a new study reported online today in Current Biology, researchers witnessed this behavior in the octopus Japetella heathi (shown) and the squid Onychoteuthis banksii. They exposed the creatures to a beam of directed blue light, as might come from certain bioluminescent predators, as well as to other stimuli such as passing shadows. When the blue light hit them, the cephalopods contracted muscles that stretched their pigment-containing cells, turning their skin red. In the wild, this quick blush hides the cephalopods from their predators, as red objects are imperceptible under blue light. Thus, J. heathi and O. banksii stay invisible, even though they're no longer transparent.

Reference
Mesopelagic Cephalopods Switch between Transparency and Pigmentation to Optimize Camouflage in the Deep
Current Biology, 10 November 2011 10.1016/j.cub.2011.10.014
http://www.cell.com/current-biology/abstract/S0960-9822%2811%2901138-9

Highlights
•Transparency and pigmentation are incomplete solutions to mesopelagic camouflage
•Mesopelagic cephalopods switch between these strategies in response to blue light
•This optimizes camouflage under both ambient light and directed bioluminescence
•Spectral data show that pigmented tissue reflects half the light of transparent tissue

Summary
Animals in the lower mesopelagic zone (6001,000 m depth) of the oceans have converged on two major strategies for camouflage: transparency and red or black pigmentation. Transparency conveys excellent camouflage under ambient light conditions, greatly reducing the conspicuousness of the animal's silhouette. Transparent tissues are seldom perfectly so, resulting in unavoidable internal light scattering. Under directed light, such as that emitted from photophores thought to function as searchlights, the scattered light returning to a viewer will be brighter than the background, rendering the animal conspicuous. At depths where bioluminescence becomes the dominant source of light, most animals are pigmented red or black, thereby reflecting little light at wavelengths generally associated with photophore emissions and visual sensitivities. However, pigmented animals are susceptible to being detected via their silhouettes. Here we show evidence for rapid switching between transparency and pigmentation under changing optical conditions in two mesopelagic cephalopods, Japetella heathi and Onychoteuthis banksii. Reflectance measurements of Japetella show that transparent tissue reflects twice as much light as pigmented tissue under direct light. This is consistent with a dynamic strategy to optimize camouflage under ambient and searchlight conditions.

Video: Showing Pigmentation Changes With Light Exposure in the Cephalopods (Duke University)
A squid and an ocotpus that dwell 600 to 1000 meters deep in the open
ocean are able to switch between transparent or opaque to evade different
predators.
Fonte: DukeUniversityNews http://www.youtube.com/user/DukeUniversityNews

Category:

Pets & Animals

Tags:

• mesopelagic
• cephalopods
• switch
• between
• transparency
• pigmentation
• optimize
• camouflage
• deep

[TiaSaysSo]

Good work Dr.Zylinski.Wonder if these cephalopods can sustain normal housekeeping activites under prolonged pigmentation?Or do they go into a state of torpor during pigmentation?

[momtoo]

Thanks. I just read a story about Japetella heathi octopus in MSNBC science and wanted to see a video of the process...YOURS was the only one!!!