Dynamic physiological changes for adaptation to background and mechanisms underlying chromatic strategy for survival in three species of fresh–water Indian minnow, Puntius
Agrawal Sita, Kumar A
Animals utilize conspicuous colour and pattern as “aposematic” colouration. Inconspicuous they are conversely exploited as cryptic colouration. For fishes lacking the ability of vocal communication such colours, patterns and their changes represent strategies of the utmost importance for the survival of individuals or of species. For example, protective colour, which constitutes part of the cryptic colouration is useful for avoiding attack by predator, while conspicuous displays function to frighten predators. Therefore, we must understand how the fish reversibly change their chromatic characteristics to survive in their habitat.The fresh water Indian teleosts, the Puntius species were used as the experimental materials Colours of fishes are due to the pigment cells (chromatophores) usually in the dermis of skin tissue, where many varieties of them are located. All the five types of chromatophores namely melanophores (both dermal and epidermal), xanthophores, erythrophores, leucophores and iridophores are represented in Puntius. Rapid changes of hues as recorded in these species and chromatic patterns are caused by the motility of these chromatophore species and aggregation of pigment granules in the parikaryon and dispersion throughout the cytoplasm are the characteristics of the cellular motility of an ordinary dendritic chromatophores. These bidirectional movements are the result of perception of the background by the optic and extraoptic (pineal) receptors and are regulated neurally (autonomic nervous system) as well as hormonally (hypothalamus, pituitary) by MSH and MCH. Melatonin appears to have a role in circadian colour changes in the fish. Various neural and hormonal receptors have been characterized along with the pharmacological nature of the chromatic fibres.
Agrawal Sita, Kumar A. Dynamic physiological changes for adaptation to background and mechanisms underlying chromatic strategy for survival in three species of fresh–water Indian minnow, Puntius . International Journal of Zoology Studies. 2021; 6(5): 10-14.