The blue phase in the color changes of fish with special reference to the role of the guanin deposits in the skin of Fundulus heteroclitus

Changes in spectral reflexions from the iridophores of the neon tetra.

“…Preliminary work using decapitated fishes in Ringer to which 5 x 10-5 M adrenaline was added showed that adrenaline causes a marked shift in spectral reflectance towards longer wavelengths confirming an earlier observation that Foster (1937) made on Funrdulu8. Fig.…”

“…Strong illumination did not result in either the pronounced reddening characteristic of exposure of the dead fish to hypotonic solutions or of the disruption of the electron dense cytoplasm layers characterized by that treatment. Foster (1937) showed that the control in the iridescent colours of the male was partly through the direct effects of light on the skin, and partly through a hormonal route, possibly an adrenergic mechanism. Both types of agent result in a change in thickness of the cytoplasm-layers that separate the guanine crystals in the reflecting multilayer stack.…”

“…One such example is provided by the male of the Killiefish Funduiu8 heteroclitU8. Foster (1933Foster ( , 1937 showed that the iridocytes in isolated strips of skin changed reversibly from blue to red within a few seconds of illumination. Foster also showed that pituitrin and adrenaline caused a reddening of the iridocytes.…”

Corneal iridescence in fishes: light‐induced colour changes in relation to structure

“…Light-induced colour changes have been reported from dermal iridophores of the male killifish, Fundulus heteroclitus, (Foster, 1933(Foster, , 1937, the cardinal tetra, 626 J. SHAND Cheirodon axelrodi, (Rohrlich, 1974) and the neon tetra, Paracheirodon innesi, (Lythgoe & Shand, 1982). In the neon tetra the colour change occurs in isolated strips of skin and an opsin-based photopigment may be located in the iridophores themselves (Lythgoe et al, 1984).…”

White Pigmentary Effectors (Leucophores) in Killifishes

“…Both species have also iridophores, commonly combined as iridosomes (which, like Odiorne, I distinguish from the "iridosomes" that Sumner and Wells record for Lebistes). The leucophores of F. majalis are characteristically, at least in the outer layer, closely associated with melanophores and melaniridosomes (described for F. heteroclitus by Foster, 1937); their central masses lie next internal to and usually hidden by the associated pigmentary bodies. Most of these outer chromatophores and chromatophore complexes are aggregated in diagonal bands crisscrossing the back and sides much the same as in Lebistes (cf.…”