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conceivably influence the evolution of λ50% (or vice versa). An analysis of the relationship between λ50%, pupil size and lens/iris relationship may thus be beneficial. 3.4.4 On Gecko Spectacle Scales Compared with snake spectacle scales, those of geckos have extraordinarily high transmittance. While thinner than snakes at 3-4 µm, they are not much thinner than a mojave rattlesnake’s (5 µm), yet the latter still exhibits the same transmittance profile as other viperids, including the strong attenuation of the UV-B and a much smaller peak at 254 nm than the gecko. Although the arboreal Gekko grossmanni is largely nocturnal and may need little protection from UV radiation (nor would its minuscule pupils allow much through anyway), Phelsuma madagascariensis grandis is active diurnally and exposed to as much UV as an arboreal snake, yet its spectacle scale lets pass a tremendous dose of UV comparable with G. grossmanni. Clearly, the gecko spectacle scale is simply engineered for maximal transmittance of all wavelengths transmissible by keratin. 3.4.5 Physical reasons for variation in λ50% As previously mentioned, it is unclear if thickness directly influences λ50%, but if so, it would not be the only factor. The coefficients of correlation calculated in the study indicate that thickness accounts only for some of the variability, and even then only in Colubridae. Other factors influencing the λ50% should be considered. The surface ultrastructure of the spectacle scale may be one such factor. Using scanning electron microscopy, Campbell et al. (1999) found the spectacle scale of a python to be generally more smooth with fewer surface ridges than in other scales of the integument. As well, they reported observations of the spectacle exhibiting less optical scatter than pit organ scales. I am unaware of any reports on the surface ultrastructure of spectacle scales in other species of snake nor any species of gecko. The ultrastructure of spectacle scales and its potential relationship with their spectral properties deserves further investigation. 73
Another potential factor that may govern spectral transmittance of the spectacle scale is the biochemical composition of the keratins that make up the scales. While much research has been conducted on the keratin composition of snake and gecko skin (Alibardi & Toni, 2005a, 2005b; Toni & Alibardi 2007a), no previous work has been done on the specifics of the spectacle keratins. This gap in our knowledge inspired the work described in Chapter 4, which will present the first investigation of the keratin composition specifically of reptilian spectacles. 74
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Investigations on the Reptilian Spe
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Abstract The eyes of snakes and mos
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Heritage Library, Smithsonian Libra
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2.2.1 Animals 36 2.2.2 Experimental
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List of Figures 1-1. The earliest a
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List of Tables 2-1. Durations of sp
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UV-A Ultraviolet A (315-400 nm) UV-
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“Il est de connaissance presque v
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1.1 Anatomy of the spectacle The si
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corneum, 2- an inner stratum corneu
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The two layers he described in the
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Figure 1-5. Illustration of the spe
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injected spectacles clearly shows t
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Figure 1-8. In vivo confocal micros
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1.1.3 The Spectacles of Geckos Most
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1.1.4 The Spectacles of Amphisbaeni
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Gymnophthalmus (spectacled tegus) a
Page 35 and 36: appreciates on observing the sadly
Page 37 and 38: hydration state (van Doorn, unpubl.
Page 39 and 40: 1.5 Adaptive Significance of the Sp
Page 41 and 42: diurnally active in hot and dry hab
Page 43 and 44: of his argument hinges on the prese
Page 45 and 46: • In Chapter 3, findings on the v
Page 47 and 48: 2.1 Introduction This introduction
Page 49 and 50: 2.2 Methods & Materials The experim
Page 51 and 52: To allow for extended high-magnific
Page 53 and 54: At 30 minutes into the experiment,
Page 55 and 56: packages. All statistical analyses
Page 57 and 58: 2.3 Results 2.3.1 Spectacle blood f
Page 59 and 60: Figure 2-7. Graph of two representa
Page 61 and 62: 2.4 Discussion The purpose of this
Page 63 and 64: vascular changes were occurring onl
Page 65 and 66: Chapter 3, Spectral Transmission of
Page 67 and 68: like the cornea, may exhibit simila
Page 69 and 70: The scales of both the right and le
Page 71 and 72: Figure 3-1. Spectral transmittance
Page 73 and 74: % Transmittance % Transmission % Tr
Page 75 and 76: % % Transmittance Transmission % %
Page 77 and 78: λ 50% (nm) 420 400 380 360 340 320
Page 79 and 80: Thickness (!m) Figure 3-7. Plot of
Page 81 and 82: Family Spearmanʼs rho p Colubridae
Page 83 and 84: virtue of both being characteristic
Page 85: nocturnal (Brattstrom 1952; Klauber
Page 89 and 90: Colubridae Colubrinae Elaphe taeniu
Page 91 and 92: Pythonidae Python sebae Rock Python
Page 93 and 94: 4.1 Introduction The reptilian spec
Page 95 and 96: thus be optimized to meet not only
Page 97 and 98: 4.2 Methods & Materials 4.2.1 Sampl
Page 99 and 100: for 15 minutes to remove all residu
Page 101 and 102: 4.3 Results 4.3.1 Keratins of Coach
Page 103 and 104: 24 kDa > 17 kDa > 12 kDa > S1 P1 V1
Page 105 and 106: 76 kDa > 52 kDa > 24 kDa > 17 kDa >
Page 107 and 108: 31 kDa > 24 kDa > 17 kDa > 12 kDa >
Page 109 and 110: 4.3.4 2D Electrophoretic Comparison
Page 111 and 112: kDa 76 - 52 - 38 - 31 - 24 - 17 - 1
Page 113 and 114: (2007a) have theorized that basic
Page 115 and 116: spectacle, this layer may be partic
Page 117 and 118: Chapter 5, Summary and Concluding R
Page 119 and 120: evaluations of the elastic modulus
Page 121 and 122: References Addison WHF, How HW. 192
Page 123 and 124: Berkley MA, Wakins DW. 1973. Gratin
Page 125 and 126: Chou BR, Hawryshyn CW. 1987. Spectr
Page 127 and 128: Fox RH, Edholm OG. 1963. Nervous co
Page 129 and 130: Hinkley JA, Savitsky AH, River G, G
Page 131 and 132: Lee P, Wang CC, Adamis AP. 1998. Oc
Page 133 and 134: Mautz WJ. 1982. Patterns of evapora
Page 135 and 136: Rice GE, Bradshaw SD. 1980. Changes
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Sillman AJ, Govardovskiĭ WI, Röhl
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Valentin G. 1879a. Ein Beitrag zur
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Appendix A One cycle of spectacle b
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