TY - JOUR

T1 - Mesopelagic cephalopods switch between transparency and pigmentation to optimize camouflage in the deep

AU - Zylinski, Sarah

AU - Johnsen, Sönke

N1 - Copyright © 2011 Elsevier Ltd. All rights reserved.

PY - 2011/11/22

Y1 - 2011/11/22

N2 - Animals in the lower mesopelagic zone (600-1,000 m depth) of the oceans have converged on two major strategies for camouflage: transparency and red or black pigmentation [1]. Transparency conveys excellent camouflage under ambient light conditions, greatly reducing the conspicuousness of the animal's silhouette [1, 2]. Transparent tissues are seldom perfectly so, resulting in unavoidable internal light scattering [2]. Under directed light, such as that emitted from photophores thought to function as searchlights [3-8], the scattered light returning to a viewer will be brighter than the background, rendering the animal conspicuous [2, 4]. 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 [3, 9-14]. However, pigmented animals are susceptible to being detected via their silhouettes [5, 9-11]. 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.

AB - Animals in the lower mesopelagic zone (600-1,000 m depth) of the oceans have converged on two major strategies for camouflage: transparency and red or black pigmentation [1]. Transparency conveys excellent camouflage under ambient light conditions, greatly reducing the conspicuousness of the animal's silhouette [1, 2]. Transparent tissues are seldom perfectly so, resulting in unavoidable internal light scattering [2]. Under directed light, such as that emitted from photophores thought to function as searchlights [3-8], the scattered light returning to a viewer will be brighter than the background, rendering the animal conspicuous [2, 4]. 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 [3, 9-14]. However, pigmented animals are susceptible to being detected via their silhouettes [5, 9-11]. 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.

KW - Animals

KW - Behavior, Animal

KW - Decapodiformes

KW - Marine Biology

KW - Octopodiformes

KW - Pacific Ocean

KW - Pigmentation

KW - Visual Perception

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

KW - Research Support, U.S. Gov't, Non-P.H.S.

U2 - 10.1016/j.cub.2011.10.014

DO - 10.1016/j.cub.2011.10.014

M3 - Article

C2 - 22079113

VL - 21

SP - 1937

EP - 1941

JO - Current Biology

JF - Current Biology

SN - 0960-9822

IS - 22

ER -