Research Areas | Marine Biological Laboratory

Camouflage & Adaptive Coloration

Nearly all animals have some sort of adaptive coloration or camouflage patterning that is often linked to a behavior to make it adaptive.

Some of the functions of adaptive coloration include:

defense against predators,
communication with conspecifics,
attracting or deceiving mates,
repelling or deceiving rivals,
signalling alarm to conspecifics and so forth,
protection from the environment (e.g., ultraviolet radiation, cold), and
approaching prey

iBioSeminar: Concepts and questions (28:00 min)

Camouflage

A primary defense against predators throughout the animal kingdom (and against the enemy during human warfare) is to avoid detection or recognition through camouflage. Achieving effective camouflage requires a suite of appropriate actions by an animal:

sensing the local environment (including the animals in it),
filtering the sensory input,
using selected sensory input to make a behavior decision,
directing the appropriate effectors (be they muscles/postures/color patterns, etc.) to achieve some form of camouflage, and
implementing the appropriate behavior to render the camouflage effective.

How many kinds of camouflage are there?

There is still active debate on how to best "categorize" camouflage. Generally the tactics involve hindering or preventing detection or recognition. Some of the generally accepted mechanisms of camouflage include:

general background resemblance (or "background matching,"
deceptive resemblance (or "masquerade" including mimicry),
disruptive coloration,
countershading/concealment of the shadow.

Other mechanisms include self-shadow concealment, obliterative shading, distractive markings, flicker-fusion camouflage, motion dazzle and motion camouflage. Ongoing research worldwide is occurring on many of these features.

Cephalopods: ultimate adaptive coloration?

A distinguishing feature of cephalopods is that individual animals can change their appearance with a speed and diversity unparalleled in the animal kingdom: we term this “rapid, neurally controlled polymorphism.” Some squids, octopuses and cuttlefish can show 30-50 different appearances. In fact, these marine invertebrates manifest most aspects of their behavior through body patterning. An example of their versatility is that – unlike other animals that use one or a few mechanisms of camouflage – cephalopods use most of the mechanisms listed above.

Sensory/motor mechanisms of achieving adaptive coloration in cephalopods

Due to their sophisticated neural control of the skin, cephalopods can adapt to a wide range of backgrounds. What sensory cues do they use to achieve background matching? Vision is probably the main cue, but cephalopods do not seem to have color vision. We are currently investigating the mechanisms and functions of polarization sensitivity in cephalopods. We have also begun to look at visual features of the background that cuttlefish use to switch on disruptive coloration.

Tactile cues seem not to be used by cuttlefish for regulating their skin texture - vision seems to be used. Olfactory cues are used by cuttlefish females to choose mates, yet we do not know if/how this translates to certain body patterns for communication. Read more about skin ultrastructure and neurobiology in the next section.

How do you study camouflage?

Field work is mandatory to experience and understand the dynamic features of light throughout each daily, lunar, seasonal, and yearly cycle. Field work also enables observation and analysis of animal behavior under natural conditions. Laboratory experiments provide detailed testing of sensory cues, motor output and sequences of behavior. Computer simulations allow additional testing of hypotheses at multiple levels of analysis.

Publications on adaptive coloration and behavior:

Allen, J. J., Akkaynak, D., Sugden, A. U., and Hanlon, R. T. (2015). Adaptive body patterning, three-dimensional skin morphology and camouflage measures of the slender filefish Monacanthus tuckeri on a Caribbean coral reef. Biological Journal of the Linnean Society, 116(2), 377–396. doi: 10.1111/bij.12598

Buresch, K. C., Ulmer, K. M., Cramer, C., McAnulty, S., Davison, W., Mathger, L. M., and Hanlon, R. T. (2015). Tactical Decisions for Changeable Cuttlefish Camouflage: Visual Cues for Choosing Masquerade Are Relevant from a Greater Distance than Visual Cues Used for Background Matching. Biological Bulletin, 229(2), 160 – 166. Pubmed: 26504156

Chiao, C. C., Chubb, C., and Hanlon, R. T. (2015). A review of visual perception mechanisms that regulate rapid adaptive camouflage in cuttlefish. Journal of Comparative Physiology A-Sensory Neural and Behavioral Physiology, 201(9), 933–945. doi: 10.1007/s00359-015-0988-5

Tyrie, E. K., Hanlon, R. T., Siemann, L. A., and Uyarra, M. C. (2015). Coral reef flounders, Bothus lunatus , choose substrates on which they can achieve camouflage with their limited body pattern repertoire. Biological Journal of the Linnean Society, 114(3), 629–638. doi: 10.1111/bij.12442

Buresch, K. C., Ulmer, K. M., Akkaynak, D., Allen, J. J., Maethger, L. M., Nakamura, M., and Hanlon, R. T. (2015). Cuttlefish adjust body pattern intensity with respect to substrate intensity to aid camouflage, but do not camouflage in extremely low light. Journal of Experimental Marine Biology and Ecology, 462, 121–126. doi: 10.1016/j.jembe.2014.10.017

Watson, A. C., Siemann, L. A., and Hanlon, R. T. (2014). Dynamic camouflage by Nassau groupers Epinephelus striatus on a Caribbean coral reef. Journal of Fish Biology, 85(5), 1634 – 1649. doi: 10.1111/jfb.12519

Akkaynak, D., Treibitz, T., Xiao, B., Gurkan, U.A., Allen, J.J., Demirci, U. and Hanlon, R.T. (2014). Use of commercial off-the-shelf digital cameras for scientific data acquisition and scene-specific color calibration. Journal of the Optical Society of America 31(2), 312-321. doi: 10.1364/JOSAA.31.000312

Chiao, C. C., Ulmer, K. M., Siemann, L. A., Buresch, K. C., Chubb, C., and Hanlon, R. T. (2013). How visual edge features influence cuttlefish camouflage patterning. Vision Research, 83, 40–7. doi: 10.1016/j.visres.2013.03.001

Staudinger, M. D., Buresch, K. C., Mäthger, L. M., Fry, C., McAnulty, S., Ulmer, K. M., and Hanlon, R. T. (2013). Defensive responses of cuttlefish to different teleost predators. The Biological Bulletin, 225(3), 161–74. Pubmed: 24445442

Ulmer, K. M., Buresch, K. C., Kossodo, M. M., Mäthger, L. M., Siemann, L. A., and Hanlon, R. T. (2013). Vertical visual features have a strong influence on cuttlefish camouflage. The Biological Bulletin, 224(2), 110–8. Pubmed: 23677976

Akkaynak, D., Allen, J. J., Mäthger, L. M., Chiao, C.-C., and Hanlon, R. T. (2013). Quantification of cuttlefish (Sepia officinalis) camouflage: a study of color and luminance using in situ spectrometry. Journal of Comparative Physiology. A Neuroethology, Sensory, Neural, and Behavioral Physiology, 199(3), 211–25. doi: 10.1007/s00359-012-0785-3

Hanlon, R. T., Chiao, C.-C., Mäthger, L. M., and Marshall, N. J. (2013). A fish-eye view of cuttlefish camouflage using in situ spectrometry. Biological Journal of the Linnean Society, 109(3), 535–551. doi: 10.1111/bij.12071

Mäthger, L. M., and Hanlon, R. T. (2012). Pigmentation or transparency? Camouflage tactics in deep-sea cephalopods. Pigment Cell & Melanoma Research, 25(3), 295–296. doi: 10.1111/j.1755-148X.2012.00985.x

Barbosa, A., Allen, J. J., Mäthger, L. M., and Hanlon, R. T. (2012). Cuttlefish use visual cues to determine arm postures for camouflage. Proceedings. Biological Sciences / The Royal Society, 279(1726), 84–90. doi: 10.1098/rspb.2011.0196

Buresch, K. C., Mäthger, L. M., Allen, J. J., Bennice, C., Smith, N., Schram, J., Chiao, C.C., and Hanlon, R. T. (2011). The use of background matching vs. masquerade for camouflage in cuttlefish Sepia officinalis. Vision Research, 51(23-24), 2362–8. doi: 10.1016/j.visres.2011.09.009

Zylinski, S., How, M.J., Osorio, D., Hanlon, R.T. and Marshall, N.J. (2011). To be seen or to hide: visual characteristics of body patterns for camouflage and communication in the Australian giant cuttlefish, Sepia apama. American Naturalist, 177(5), 681-690. doi: 10.1086/659626

Chiao, C.-C., Wickiser, J. K., Allen, J. J., Genter, B., and Hanlon, R. T. (2011). Hyperspectral imaging of cuttlefish camouflage indicates good color match in the eyes of fish predators. Proceedings of the National Academy of Sciences of the United States of America, 108(22), 9148–53. doi: 10.1073/pnas.1019090108

Staudinger, M. D., Hanlon, R. T., and Juanes, F. (2011). Primary and secondary defences of squid to cruising and ambush fish predators: variable tactics and their survival value. Animal Behaviour, 81(3), 585–594. doi: 10.1016/j.anbehav.2010.12.002

Allen, J.J., Mäthger,L.M., Buresch, K.C., Fetchko, T. Gardner, M. and Hanlon, R.T. (2010) Night vision by cuttlefish enables changeable camouflage. J. Experimental Biology 213: 3953-3960. doi: 10.1242/jeb.044750

Allen, J. J., Mäthger, L. M., Barbosa, A., Buresch, K. C., Sogin, E., Schwartz, J., and Hanlon, R. T. (2010). Cuttlefish dynamic camouflage: responses to substrate choice and integration of multiple visual cues. Proceedings. Biological Sciences / The Royal Society, 277 (1684), 1031–9. doi: 10.1098/rspb.2009.1694

Hanlon, R.T., Watson, A.C., and Barbosa, A. (2010). A “mimic octopus” in the Atlantic: flatfish mimicry and camouflage by Macrotritopus defilippi. Biological Bulletin 218 (1): 15-24. (Editor’s Choice Article and Cover Shot) Pubmed: 20203250

Chiao, C.C., Chubb, C., Buresch, K., Allen, J., Barbosa, A., Mäthger, L.M., Hanlon, R.T. (2010). Mottle camouflage patterns in cuttlefish: quantitative characterization and visual stimuli that evoke them. Journal of Experimental Biology 213: 187-199. doi: 10.1242/jeb.030247

Hanlon, R.T., & Messenger, J.B. 1996. Cephalopod Behaviour. Cambridge University Press.

Hanlon R.T., Chiao C-C., Mäthger, L.M., Barbosa A., Buresch K.C., & Chubb, C. 2009. Cephalopod dynamic camouflage: bridging the continuum between background matching and disruptive coloration. Philosophical Transactions of the Royal Society B 364: 429-437.

Williams, S.B., Pizarro, O., How, M., Mercer, D., Powell, G., Marshall, J., & Hanlon, R. 2009. Surveying nocturnal cuttlefish camouflage behaviour using an AUV. IEEE International Conference on Robotics and Automation: 214-219.

Mäthger, L.M., Shashar, N., & Hanlon, R.T. 2009. Do cephalopods communicate using polarized light reflections from their skin? Journal of Experimental Biology 212: 2133-2140. (Featured Commentary)

Mäthger, L.M., Barbosa, A., & Hanlon, R.T. 2009. Cuttlefish use visual cues to control 3-dimensional skin papillae for camouflage. Journal of Comparative Physiology A 195: 547-555.

Chiao, C-C., Chubb, C., Buresch, K., Siemann, L., & Hanlon, R.T. 2009. The scaling effects of substrate texture on camouflage patterning in cuttlefish. Vision Research 49 (13): 1647-1656.

Mäthger, L.M., Denton, E.J., Marshall, J., & Hanlon, R.T. 2008. Mechanisms and behavioral functions of structural coloration in cephalopods. Journal of the Royal Society Interface 6: S149-S164.

Hanlon, R.T., Conroy, L.-A., & Forsythe, J.W. 2008. Mimicry and foraging behaviour of two tropical sand-flat octopus species off North Sulawesi, Indonesia. Biological Journal of the Linnean Society, 93: 23-38.

Mäthger, L.M., Chiao, C-C., Barbosa, A, Buresch, K., Kaye, S., & Hanlon, R.T. 2007. Disruptive coloration elicited on controlled natural substrates in cuttlefish, Sepia officinalis J. Exp. Biol. 210: 2657-2666.

Mäthger, L.M., & Cronin, T.W. 2007. Spectral and spatial properties of the polarized light reflections on the arms of squid (Loligo pealeii) and cuttlefish (Sepia officinalis L.). Journal of Experimental Biology. 210: 3624-3635.

Mäthger, L.M., & Hanlon, R.T. 2007. Malleable skin coloration in cephalopods: selective reflectance, transmission and absorbance of light by chromatophores and iridophores. Cell and Tissue Research 329: 179-186.

Hanlon, R.T. 2007. Cephalopod dynamic camouflage. Current Biology 17 (11): 400-404.

Hanlon, R.T., Naud, M.-J., Forsythe, J.W., Hall, K., Watson, A.C., & McKechnie, J. 2007. Adaptable night camouflage by cuttlefish. American Naturalist 169 (4): 543-551.

Barbosa, A., Mäthger, L.M., Chubb, C., Florio, C., Chiao, C-C., & Hanlon, R.T. 2007. Disruptive coloration in cuttlefish: a visual perception mechanism that regulates ontogenetic adjustment of skin patterning. Journal of Experimental Biology 210: 1139-1147.

Mäthger, L.M., & Hanlon, R.T. 2006. Anatomical basis for camouflaged polarized light communication in squid. Biology Letters 2(4): 494-496.

Chiao, C-C., Kelman, E.J., & Hanlon, R.T. 2005. Disruptive body patterning of cuttlefish (Sepia officinalis) requires visual information regarding edges and contrast of objects in natural substrate backgrounds. Biological Bulletin. 208: 7-11.

Anderson, J.C., Baddeley, R.J., Osorio, D., Shashar, N., Tyler, C.W., Ramachandran, V.S., Cook A.C., & Hanlon, R.T. 2003. Modular organization of adaptive colouration in flounder and cuttlefish revealed by independent component analysis. Network: Comput. Neural Syst. 14: 321-333

Chiao, C-C., & Hanlon, R.T. 2001. Cuttlefish camouflage: visual perception of size, contrast and number of white squares on artificial substrata initiates disruptive coloration. J. Exp. Biol. 204: 2119-2125.

Chiao, C-C., & Hanlon, R.T. 2001. Cuttlefish cue visually on area—not shape or aspect ratio—of light objects in the substrate to produce disruptive body patterns for camouflage. Biol. Bull. 201:269-270.

Hanlon, R.T., Forsythe, J.W., & Joneschild, D.E. 1999. Crypsis, conspicuousness, mimicry and polyphenism as antipredator defences of foraging octopuses on Indo-Pacific coral reefs, with a method of quantifying crypsis from video tapes. Biol. J. Linn. Soc. 66: 1-22.

Hanlon, R.T., Maxwell, M.R., Shashar, N., Loew, E.R., & Boyle, K.-L. 1999. An ethogram of body patterning behavior in the biomedically and commercially valuable squid Loligo pealei off Cape Cod, Massachusetts. Biol. Bull. 197(1): 49-62.

Shashar, N., & Hanlon, R.T. 1997. Squids (Loligo pealei and Euprymna scolopes) can exhibit polarized light patterns produced by their skin. Biol. Bull. 193(2): 207-208.

Forsythe, J.W., & Hanlon, R.T. 1997. Foraging and associated behavior by Octopus cyanea Gray, 1849 on a coral atoll, French Polynesia. J. Exp. Mar. Biol. Ecol. 209: 15-31.

Cornwell, C.J., Messenger, J.B., & Hanlon, R.T. 1997. Chromatophores and body patterning in the squid Alloteuthis subulata. J. mar. biol. Assoc. U.K. 77: 1243-1246.

DiMarco, F.P. ,& Hanlon, R.T. 1997. Agonistic behavior in the squid Loligo plei (Loliginidae, Teuthoidea): Fighting tactics and the effects of size and resource value. Ethology 103(2): 89-108.

Hanlon, R.T., & Messenger, J.B. 1996. Cephalopod Behaviour. Cambridge University Press.

Adamo, S.A., & Hanlon, R.T. 1996. Do cuttlefish (Cephalopoda) signal their intentions to conspecifics during agonistic encounters? Anim. Behav. 52: 73-81.

Hanlon, R.T., Smale, M.J., & Sauer, W.H.H. 1994. An ethogram of body patterning behavior in the squid Loligo vulgaris reynaudii on spawning grounds in South Africa. Biol. Bull. 187(3): 363-372.

Cooper, K.M., Hanlon, R.T., & Budelmann, B.U. 1990. Physiological color change in squid iridophores II. Ultrastructural mechanisms in Lolliguncula brevis. Cell Tissue Res. 259: 15-24.

Hanlon, R.T., Cooper, K.M., Budelmann, B.U., & Pappas, T.C. 1990. Physiological color change in squid iridophores I. Behavior, morphology and pharmacology in Lolliguncula brevis. Cell Tissue Res. 259: 3-14.

Cooper, K.M., Hanlon, R.T., & Budelmann, B.U. 1990. Physiological color change in squid iridophores II. Ultrastructural mechanisms in Lolliguncula brevis. Cell Tissue Res. 259: 15-24.

Novicki, A., Budelmann, B.U., & Hanlon, R.T. 1990. Brain pathways of the chromatophore system in the squid Lolliguncula brevis. Brain Res. 519(1-2): 315-323.

Hanlon, R.T., & Wolterding, M.R. 1989. Behavior, body patterning, growth and life history of Octopus briareus cultured in the laboratory. Am. Malacol. Bull. 7(1): 21-45.

Hanlon, R.T. 1988. Behavioral and body patterning characters useful in taxonomy and field identification of cephalopods. Malacologia 29(1): 247-264.

Hanlon, R.T., Messenger, J.B. 1988. Adaptive coloration in young cuttlefish (Sepia officinalis L.): The morphology and development of body patterns and their relation to behaviour. Phil. Trans. R. Soc. Lond. B 320: 437-487.

Colorful Skin: Changeable Pigments, Reflectors & 3D Shape

The colorful and changeable skin of cephalopods is an elegant arrangement of pigments and reflectors. We are interested in their gross and fine morphology, their control and their optical output. Octopus and cuttlefish have the unique ability for “shape shifting” skin; that is, controllable papillae that can render the skin bumpy or smooth to any degree. A wide variety of techniques is used to accomplish this research: light, electron and confocal microscopy; macrophotography and videography; underwater photography; electrophysiology, neuronal staining and tracing; and spectrometry (in the lab and the field). We collaborate with artists, modelers, materials scientists and engineers to determine how cephalopods may inspire the development of novel materials such as fabrics and cosmetics.

iBioSeminar: Changeable Skin (31:00 min)

Publications on skin ultrastructure and neurobiology:

Kingston, A. C. N., Kuzirian, A. M., Hanlon, R. T., & Cronin, T. W. (2015). Visual phototransduction components in cephalopod chromatophores suggest dermal photoreception. The Journal of Experimental Biology, 218(Pt 10), 1596–602. doi: 10.1242/jeb.117945

Kripke, E., Senft, S., Mozzherin, D., & Hanlon, R. (2015). Visualizing Biological Complexity in Cephalopod Skin: A Synergy of Art and Science Technologies. Leonardo, 48(5), 486–487. doi: 10.1162/LEON_a_01124

Kingston, A. C., Wardill, T. J., Hanlon, R. T., & Cronin, T. W. (2015). An Unexpected Diversity of Photoreceptor Classes in the Longfin Squid, Doryteuthis pealeii. PLoS One, 10(9). doi: 10.1371/journal.pone.0135381

Allen, J. J., Akkaynak, D., Sugden, A. U., & Hanlon, R. T. (2015). Adaptive body patterning, three-dimensional skin morphology and camouflage measures of the slender filefish Monacanthus tuckeri on a Caribbean coral reef. Biological Journal of the Linnean Society, 116(2), 377–396. doi: 10.1111/bij.12598

Yu, C., Li, Y., Zhang, X., Huang, X., Malyarchuk, V., Wang, S., Shi, Y., Gao, L., Su, Y., Zhang, Y., Xu, H., Hanlon, R. T., Rogers, J. A. (2014). Adaptive optoelectronic camouflage systems with designs inspired by cephalopod skins. Proceedings of the National Academy of Sciences of the United States of America, 111(36), 12998–13003. doi: 10.1073/pnas.1410494111

Bell, G. R. R., Mäthger, L. M., Gao, M., Senft, S. L., Kuzirian, A. M., Kattawar, G. W., & Hanlon, R. T. (2014). Diffuse white structural coloration from multilayer reflectors in a squid. Advanced Materials, 26(25), 4352–6. doi: 10.1002/adma.201400383

Gonzalez-Bellido, P. T., Wardill, T. J., Buresch, K. C., Ulmer, K. M., & Hanlon, R. T. (2014). Expression of squid iridescence depends on environmental luminance and peripheral ganglion control. Journal of Experimental Biology, 217(Pt 6), 850–858. doi: 10.1242/jeb.091884

Allen, J. J., Bell, G. R. R., Kuzirian, A. M., Velankar, S. S., & Hanlon, R. T. (2014). Comparative Morphology of Changeable Skin Papillae in Octopus and Cuttlefish. Journal of Morphology, 275(4), 371–390. doi: 10.1002/jmor.20221

Deravi, L. F., Magyar, A. P., Sheehy, S. P., Bell, G. R. R., Mäthger, L. M., Senft, S. L., Wardill, T.J., Lane, W.S., Kuzirian, A.M., Hanlon, R.T., Hu, E.L., & Parker, K. K. (2014). The structure-function relationships of a natural nanoscale photonic device in cuttlefish chromatophores. Journal of the Royal Society, Interface / the Royal Society, 11(93), 20130942. doi: 10.1098/rsif.2013.0942

Mäthger, L. M., Senft, S. L., Gao, M., Karaveli, S., Bell, G. R. R., Zia, R., … Hanlon, R. T. (2013). Bright White Scattering from Protein Spheres in Color Changing, Flexible Cuttlefish Skin. Advanced Functional Materials, 23(32), 3980–3989. doi: 10.1002/adfm.201203705

Allen, J. J., Bell, G. R. R., Kuzirian, A. M., & Hanlon, R. T. (2013). Cuttlefish skin papilla morphology suggests a muscular hydrostatic function for rapid changeability. Journal of Morphology, 274(6), 645–56. doi: 10.1002/jmor.20121

Bell, G. R. R., Kuzirian, A. M., Senft, S. L., Mäthger, L. M., Wardill, T. J., & Hanlon, R. T. (2013). Chromatophore radial muscle fibers anchor in flexible squid skin. Invertebrate Biology, 132(2), 120–132. doi: 10.1111/ivb.12016

Kreit, E., Mäthger, L. M., Hanlon, R. T., Dennis, P. B., Naik, R. R., Forsythe, E., & Heikenfeld, J. (2013). Biological versus electronic adaptive coloration: how can one inform the other? Journal of the Royal Society, Interface / the Royal Society, 10(78), 20120601. doi: 10.1098/rsif.2012.0601

Wardill, T. J., Gonzalez-Bellido, P. T., Crook, R. J., & Hanlon, R. T. (2012). Neural control of tuneable skin iridescence in squid. Proceedings. Biological Sciences / The Royal Society, 279(1745), 4243–52. doi: 10.1098/rspb.2012.1374

Mäthger, L. M., Bell, G. R. R., Kuzirian, A. M., Allen, J. J., & Hanlon, R. T. (2012). How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings? The Journal of Experimental Biology, 215(Pt 21), 3752–7. doi: 10.1242/jeb.076869

Izumi, M., Sweeney, A.M., DeMartini, D., Weaver, J. C., Powers, M.L., Tao, A., Silvas, T.V., Kramer, R.M., Crookes-Goodson, W.J., Mäthger, L.M., Naik, R.R., Hanlon, R.T., & Morse, D.E., 2010. Changes in reflectin protein phosphorylation are associated with dynamic iridescence in squid. J. Royal Society Interface 7: 549-560.

Mäthger, L.M., Denton, E.J., Marshall, J., & Hanlon, R.T. 2009. Mechanisms and behavioral functions of structural coloration in cephalopods. Journal of the Royal Society Interface 6: S149-S164.

Mäthger, L.M., Shashar, N., & Hanlon, R.T. 2009. Do cephalopods communicate using polarized light reflections from their skin? Journal of Experimental Biology 212: 2133-2140. (Featured Commentary)

Allen, J.J., Mäthger, L.M., Barbosa, A., & Hanlon, R.T. 2009. Cuttlefish use visual cues to control 3-dimensional skin papillae for camouflage. Journal of Comparative Physiology A 195: 547-555.

Miserez, A., Weaver, J.C., Pedersen, P.B., Schneeberk, T., Hanlon, R.T., Kisailus, D., & Birkedal, H. 2008. Microstructural and biochemical characterization of the nano-porous sucker rings from Dosidicus gigas. Advanced Materials 20: 1-6.

Mäthger, L.M., Denton, E.J., Marshall, J., & Hanlon, R.T. 2008. Mechanisms and behavioral functions of structural coloration in cephalopods. Journal of the Royal Society Interface 6: S149-S164.

Sutherland, R.L., Mäthger, L.M., Hanlon, R.T., Urbas, A.M., & Stone, M.O. 2008. Cephalopod coloration model. I. Squid chromatophores and iridophores. Journal of the Optical Society of America, 25 (3): 588-599.

Sutherland, R.L., Mäthger, L M., Hanlon, R.T., Urbas, A.M., & Stone, M.O. 2008. Cephalopod coloration model. II. Multiple layer skin effects. Journal of the Optical Society of America, 25 (8): 2044-2054.

Chiou, T.H., Hanlon, R.T., Mäthger, L.M., & Cronin, T.W. 2007. Spectral and spatial properties of the polarized light reflections on the arms of squid (Loligo pealeii) and cuttlefish (Sepia officinalis L.). Journal of Experimental Biology. 210: 3624-3635.

Mäthger, L.M., Barbosa, A., Miner, S., & Hanlon, R.T. 2006. Color blindness and contrast perception in cuttlefish (Sepia officinalis). Vision Research 46: 1746-1753.

Saidel, W.M., Shashar, N., Schmolesky, M.T., & Hanlon, R.T. 2005. Discriminative responses of squid (Loligo pealeii) photoreceptors to polarized light. Comparative Biochemistry & Physiology A: 142/3: 340-346.

Shashar, N., Borst, D.T., Ament, S.A., Saidel, W.M., Smolowitz, R.M., & Hanlon, R.T. 2001. Polarization reflecting iridophores in the arms of the squid Loligo pealeii. Biol. Bull. 201:267-268.

Cooper, K.M., Hanlon, R.T., & Budelmann, B.U. 1990. Physiological color change in squid iridophores II. Ultrastructural mechanisms in Lolliguncula brevis. Cell Tissue Res. 259(1): 15-24.

Novicki, A., Budelmann, B.U., & Hanlon, R.T. 1990. Brain pathways of the chromatophore system in the squid Lolliguncula brevis. Brain Res. 519(1- 2): 315-323.

Cooper, K.M., & Hanlon, R.T. 1986. Correlation of iridescence with changes in iridophore platelet ultrastructure in the squid Lolliguncula brevis. J. exp. Biol. 121: 451-455.

Dubas, F., Hanlon, R.T., Ferguson, G.P., & Pinsker, H.M. 1986. Localization and stimulation of chromatophore motoneurones in the brain of the squid, Lolliguncula brevis. J. exp. Biol. 121: 1-25.

Dubas, F., Leonard, R.B., & Hanlon, R.T. 1986. Chromatophore motoneurons in the brain of the squid, Lolliguncula brevis: An HRP study. Brain Res. 374(1): 21-29.

Florey, E., Dubas, F., & Hanlon, R.T. 1985. Evidence for L-glutamate as a transmitter substance of motoneurons innervating squid chromatophore muscles. Comp. Biochem. Physiol. C. 82(2): 259-268.

Hanlon, R.T. 1982. The functional organization of chromatophores and iridescent cells in the body patterning of Loligo plei (Cephalopoda: Myopsida). Malacologia 23(1): 89-119.

Sensory Ecology

Overall, we are interested in how cephalopods use their senses of vision and olfaction to carry out many of their primary behaviors in the field. For example, the functional morphology and neurobiology of the chromatophore system of cephalopods are studied on a variety of cephalopod species, and image analysis techniques are being developed to study crypsis and the mechanisms that enable cryptic body patterns to be neurally regulated by visual input. Various aspects of predation, antipredator defenses, and reproduction are conducted in field sites worldwide

Laboratory studies on the mechanisms and functions of polarized light sensitivity in cephalopods are underway. Olfactory sensing by Nautilus (which functions in food detection and location as well as mate choice) has been studied in the laboratory. Visual features that octopuses use for maze learning are also investigated. Lab experiments in large indoor seawater tanks are being conducted to determine how male squids, Loligo pealeii, use visual then contact chemical cues in egg capsules to initiate highly robust agonistic behavior.

iBioSeminar: Exploring Mechanisms of Visual Perception (51:00 min)

Publications on sensory ecology:

Mäthger, L.M., Shashar, N., & Hanlon, R.T. 2009. Do cephalopods communicate using polarized light reflections from their skin? Journal of Experimental Biology 212: 2133-2140. (Featured Commentary)

Crook, R., Hanlon, R.T., & Basil, J. In press, 2009. Memory of visual and topographical features suggests spatial learning in the ancient cephalopod Nautilus. J. Comparative Psychology.

Wilson, M., Hanlon, R.T., Tyack, P.L., & Madsen, P.T. 2007. Intense ultrasonic clicks from echolocating toothed whales do not elicit anti-predator responses or debilitate the squid Loligo pealeii. Biology Letters 3(3): 225-227.

Madsen, P.T., Wilson, M., Johnson, M., Hanlon, R.T., Bocconcelli, A., Aguilar Soto, N., & Tyack, P.T. 2007. Clicking for calamari: toothed whales can echolocate squid Loligo pealeii. Aquatic Biology 1: 141-150. (Feature Article)

Mäthger, L.M., Chiao, C-C., Barbosa, A., Buresch, K., Kaye, S., & Hanlon, R.T. 2007. Disruptive coloration elicited on controlled natural substrates in cuttlefish, Sepia officinalis J. Exp. Biol. 210: 2657-2666.

Mäthger, L.M., & Hanlon, R.T. 2007 Malleable skin coloration in cephalopods: selective reflectance, transmission and absorbance of light by chromatophores and iridophores. Cell and Tissue Research 329, 179–186.

Wilson, M., Hanlon, R.T., Tyack, P.L., & Madsen, P.T. Intense ultrasonic clicks from echolocating toothed whales do not elicit anti-predator responses or debilitate the squid Loligo pealeii. Biology Letters

Mäthger, L.M., Barbosa, A., Miner, S., & Hanlon, R.T. 2006. Color blindness and contrast perception in cuttlefish (Sepia officinalis). Vision Research 46: 1746-1753.

Mäthger, L.M., & Hanlon, R.T. 2006. Anatomical basis for camouflaged polarized light communication in squid. Biology Letters 2(4): 494-496.

Boal, J.G., Shashar, N., Grable, M., Vaughan, K.H., Loew, E.R., & Hanlon, R.T. 2004. Behavioral evidence for intraspecific signals with achromatic and polarized light by cuttlefish (Mollusca: Cephalopoda). Behaviour 141: 837-861.

Hanlon, R.T., & Shashar, N. 2003. Aspects of the sensory ecology of cephalopods. In: Sensory Processing in the Aquatic Environment. Collin, S.P.; Marshall, N.J. (eds.). Springer-Verlag, New York, pp. 266-282.

King, A.J., Adamo, S.A., & Hanlon, R.T. 2003. Squid egg mops provide sensory cues for increased agonistic behavior between male squid. Anim. Behav. 66: 49-58.

Karson, M.A., Boal, J.G., Usook, S., & Hanlon, R.T. 2003. Experimental evidence for spatial learning in the cuttlefish, Sepia officinalis. J. Comp. Psychol. Vol. 117, No. 2, 149-155.

Buresch, K.C., Boal, J.G., Knowles, J., DeBose, J., Nichols, A., Erwin, A., Painter, S.D,; Nagle, G.T., & Hanlon, R.T. 2003. Contact chemosensory cues in egg bundles elicit male-male agonistic conflicts in the squid Loligo pealeii (Mollusca: Cephalopoda). J. Chem. Ecol. 29(3):547-560.

Basil, J.A., Lazenby, G.B., Nakanuku, L., & Hanlon, R.T. 2002. Female Nautilus are attracted to male conspecific odor. Bull. Mar. Sci. 70(1):217-225.

Shashar, N., Milbury, C.A., & Hanlon, R.T. 2002. Polarization vision in cephalopods: neuroanatomical and behavioral features that illustrate aspects of form and function. Mar. Freshwat. Behav. Physiol. 35(1-2):57-68.

Grable, M.M., Shashar, N., Gilles, N.L., Chiao, C-C., & Hanlon, R.T. 2002 Cuttlefish body patterns as a behavioral assay to determine polarization perception. Biol. Bull., 203: 232 234.

Buresch, K.C., Boal, J.G., Knowles, J., DeBose, J., Nichols, A., Erwin, A., Painter, S.D., Nagle, G.T., & Hanlon, R.T. 2003 Contact chemosensory cues in egg bundles elicit male-male agonistic conflicts in the squid Loligo pealeii (Mollusca: Cephalopoda). J. Chem. Ecol., Vol 29, No. 3, March

Shashar, N., Hagan, R., Boal, J.G., & Hanlon, R.T. 2000. Cuttlefish use polarization sensitivity in predation on silvery fish. Vision Res. 40(1): 71-75.

Basil, J.A., Hanlon, R.T., Sheikh, S.I., & Atema, J. 2000. Three-dimensional odor tracking by Nautilus pompilius. J. Exp. Biol. 203(9): 1409-1414.

Boal, J.G., Wittenberg, K.M., & Hanlon, R.T. 2000. Observational learning does not explain improvement in predation tactics by cuttlefish (Mollusca: Cephalopoda). Behav. Processes 52:141-153.

King, A.J., Adamo, S.A., & Hanlon, R.T. 1999. Contact with squid egg capsules increases agonistic behavior in male squid (Loligo pealei). Biol. Bull. 197: 256.

Shashar, N., Hanlon, R.T., & Petz, A.deM. 1998. Polarization vision helps detect transparent prey. Nature 393(6682): 222-223.

Shashar, N., & Hanlon, R.T. 1997. Squids (Loligo pealei and Euprymna scolope) can exhibit polarized light patterns produced by their skin. Biol. Bull. 193(2): 207-208.

Adamo, S.A., & Hanlon, R.T. 1996. Do cuttlefish (Cephalopoda) signal their intentions to conspecifics during agonistic encounters? Anim. Behav. 52: 73-81.

Hanlon, R.T., Bidwell, J.P., & Tait, R. 1989. Strontium is required for statolith development and thus normal swimming behaviour of hatchling cephalopods. J. exp. Biol. 141: 187-195.

Hanlon, R.T., & Budelmann, B.-U. 1987. Why cephalopods are probably not "deaf." Am. Nat. 129(2): 312-317.

Sexual Selection

Sexual selection theory is being tested using squid and cuttlefish. Field and laboratory studies focus on mechanisms of agonistic behavior, female mate choice, and sperm competition. The latter studies involve DNA fingerprinting to determine paternity and help assess alternative mating tactics.

Publications on sexual selection:

Marian, J.E.A.R., Apostólico, L.H., Chiao, C.C., Hanlon, R.T., Hirohashi, N., Iwata, Y., Mather, J.A., Sato, N., Shaw, P.W. (2019). Male alternative reproductive tactics and associated evolution of anatomical characteristics in Loliginid squid. Frontiers in Physiology, 10(1281). DOI: 10.3389/fphys.2019.01281

Buresch, K. C., Maxwell, M. R., & Hanlon, R.T. In press, 2009. Temporal dynamics of mating and paternity in the squid Loligo pealeii. Marine Ecology Progress Series

Hanlon, R.T., Naud, M.-J,; Shaw, P.W., & Havenhand, J.N. 2005. Transient sexual mimicry leads to fertilisation. Nature 430: 212.

Naud, M.-J., Hanlon, R.T., Hall, K.C., Shaw, P.W., & Havenhand, J.N. 2004. Behavioral and genetic assessment of mating success in a natural spawning aggregation of the giant cuttlefish (Sepia apama) in southern Australia. Animal Behaviour 67: 1043-1050.

Buresch, K.C., Boal, J.G., Knowles, J., DeBose, J., Nichols, A., Erwin, A., Painter, S.D., Nagle, G.T., & Hanlon, R.T. 2003. Contact chemosensory cues in egg bundles elicit male-male agonistic conflicts in the squid Loligo pealeii (Mollusca: Cephalopoda). J. Chem. Ecol. 29(3):547-560.

Hanlon, R.T., Smale, M.J., & Sauer, W.H.H. The mating system of the squid Loligo vulgaris reynaudii (Cephalopoda, Mollusca) off South Africa: Fighting, guarding, sneaking, mating and egg laying behavior. Bull. Mar. Sci. 71 (1) 331-345.

Hall, K.C., & Hanlon, R.T. 2002. Principal features of the mating system of a large spawning aggregation of the giant Australian cuttlefish Sepia apama (Mollusca: Cephalopoda). Mar. Biol. 140(3):533-545.

Buresch, K.M., Hanlon, R.T., Maxwell, M.R., & Ring, S. 2001. Microsatellite DNA markers indicate a high frequency of multiple paternity within individual field-collected egg capsules of the squid Loligo pealeii. Mar. Ecol. Prog. Ser. 210: 161-165.

Maxwell, M.R., Buresch, K.M., & Hanlon, R.T. 2000. Pattern of inheritance of microsatellite loci in the squid Loligo pealeii (Mollusca: Cephalopoda). Mar. Biotechnol. 2: 517-521.

Maxwell, M.R., & Hanlon, R.T. 2000. Female reproductive output in the squid Loligo pealeii: multiple egg clutches and implications for a spawning strategy. Mar. Ecol. Prog. Ser. 199: 159-170.

King, A.J., Adamo, S.A., & Hanlon, R.T. 1999. Contact with squid egg capsules increases agonistic behavior in male squid (Loligo pealei). Biol. Bull. 197: 256.

Hanlon, R.T., Ament, S.A., Gabr, H. 1999. Behavioral aspects of sperm competition in cuttlefish, Sepia officinalis (Sepioidea: Cephalopoda). Mar. Biol. 134: 719-728.

Hanlon, R.T. 1998. Mating systems and sexual selection in the squid Loligo: How might commercial fishing on spawning squids affect them? Calcofi Rep. 39: 92-100.

Maxwell, M.R., Macy, W.K., Odate, S., & Hanlon, R.T. 1998. Evidence for multiple spawning by squids (Loligo pealei) in captivity. Biol. Bull. 195(2): 225-226.

Fisheries, Aquaculture & Conservation

Population structure and reproductive success in several highly valuable squid fisheries (Loligo vulgaris reynaudii in South Africa, Loligo pealeii in the NE United States, Loligo opalescens in California) are being assessed for fishery management and conservation. We also culture species of commercial and biomedical importance in the sophisticated seawater systems of the Marine Resources Center. For example, the toadfish Opsanus beta is used in vestibular research related to human medicine, yet the species is difficult to obtain from nature. Thus, we are performing the first mariculture experiments to culture toadfish through the life cycle to provide the biomedical community with high-quality experimental animals. Such an approach lightens the impact of collecting toadfish from the natural environment..

Publications on fisheries, aquaculture & conservation:

Miserez, A., Weaver, J.C., Pedersen, P.B., Schneeberk, T., Hanlon, R.T., Kisailus, D., & Birkedal, H. 2009. Microstructural and biochemical characterization of the nano-porous sucker rings from Dosidicus gigas. Advanced Materials 20: 1-6.

Buresch, K.C., Gerlach, G., & Hanlon, R.T. 2006. Multiple genetic stocks of longfin squid Loligo pealeii in the NW Atlantic: stocks segregate inshore in summer, but aggregate offshore in winter. Mar Ecol Prog Ser, 310: 263–270.

Foote, K.G., Hanlon, R.T., Iampietro, P.J. & Kvitek, R.G. 2006. Acoustic detection and quantification of benthic egg beds of the squid Loligo opalescens in Monterey Bay, California. Journal of the Acoustical Society of America, 119 (2) : 844-856

Mensinger, A.F., Hanlon, R.T., & Walsh, P.J. 2005. Blood biochemistry of the toadfish Opsanus tau. Journal of Aquatic Animal Health 17: 170-176.

Hanlon, R.T., Kangas, N., & Forsythe, J.W. 2004. Egg capsule deposition and how behavioral interactions influence spawning rate in the squid Loligo opalescens in Monterey Bay, California. Marine Biology 145:923-930.

Forsythe, J.W., Kangas, N., & Hanlon, R.T. 2004. Does the California Market Squid, Loligo opalescens, spawn naturally during the day or at night? A note on the successful use of ROVs to obtain basic fisheries biology data. Fish. Bull. 102: 389-392.

Mensinger, A.F., Price, N.N., Richmond, H.E., Forsythe, J.W., & Hanlon, R.T. 2003. Mariculture of the oyster toadfish: juvenile growth and survival. North American Journal of Aquaculture 65:289-299.

Hanlon, R.T., Smale, M.J., Sauer, W.H.H. 2002 The mating system of the squid Loligo vulgaris reynaudii (Cephalopoda, Mollusca) off South Africa: Fighting, guarding, sneaking, mating and egg laying behavior. Bull. Mar. Sci. 71 (1) 331-345.

Mensinger, A.F., Stephenson, K.A., Pollema, S.L., Richmond, H.E., Price, N., & Hanlon, R.T. 2001. Mariculture of the toadfish, Opsanus tau. Biol. Bull. 201:282-283.

Hatfield, E.M.C., Hanlon, R.T., Forsythe, J.W., & Grist, E.P.M. 2001. Laboratory testing of a growth hypothesis for juvenile squid Loligo pealeii (Cephalopoda: Loliginidae). Can. J. Fish. Aquat. Sci. 58(5):845-857.

Maxwell, M.R., & Hanlon, R.T. 2000. Female reproductive output in the squid Loligo pealeii: multiple egg clutches and implications for a spawning strategy. Mar. Ecol. Prog. Ser. 199: 159-170.

Tang, K.Q., Price, N.N., O’Neill, M.D., Mensinger, A.F., & Hanlon, R.T. 1999. Temperature effects on first-year growth of cultured oyster toadfish, Opsanus tau. Biol. Bull. 197(2): 247-248.

Hanley, J.S., Shashar, N., Smolowitz, R., Mebane, W., & Hanlon, R.T. 1999. Soft-sided tanks improve long-term health of cultured cuttlefish. Biol. Bull. 197: 237-238.

Hanlon, R.T. 1998. Mating systems and sexual selection in the squid Loligo: How might commercial fishing on spawning squids affect them? Calcofi Rep. 39: 92-100.

Maxwell, M.R., Macy, W.K., Odate, S., & Hanlon, R.T. 1998. Evidence for multiple spawning by squids (Loligo pealei) in captivity. Biol. Bull. 195(2): 225-226.

O’Neill, M.D., Wesp, H.M., Mensinger, A.F., & Hanlon, R.T. 1998. Initial baseline blood chemistry of the oyster toadfish, Opsanus tau. Biol. Bull. 195(2): 228-229.

Hanley, J.S., Shashar, N., Smolowitz, R., Bullis, R.A., Mebane, W.N., Gabr, H.R., & Hanlon, R.T. 1998. Modified laboratory culture techniques for the European cuttlefish Sepia officinalis. Biol. Bull. 195(2): 223-225.