‘The skin together with its derivatives [Glands, Hair, Nails, Hoofs, Horns, Scales, Spines, receptors etc.] is referred to as the integument’. The integument or cutis [Latin cutis = living skin; >cutaneous = pertaining to skin] or simply skin [Middle English skyn, skinn from Old Norse skinn = animal hide, fur] is the outermost covering of the body. Skin is often not only described as the ‘largest organ’ of the body but it is the first organ that is visible or touched when any animal is handled while practicing identification of the type of organism. Although simple to appear, the skin / integument is yet a complex organ, performing many functions for the body viz., protection (by generating exoskeleton and secreting slime or mucus), providing various patterns of colouration, locomotion, food storage, respiration, excretion, sensation (irritability), sexual recognition, etc. In highly specialized fishes, the electric organs, venomous glands, light emitting photophores etc. are also the products of skin. Hence it has been aptly being called as the ‘jack of all trades’ (but ‘master of none’) because all the functions are performed with the aid of other systems of body. Simply to derive that it is alone not so vital that it may threaten the vitality of an animal. The Integument and its derivatives (Hard and Soft) are discussed from Agnatha to Gnathostomata in Chapters 1 to 4. Chapter 5 deals with the significance of the Scales whereas Chapter 6 elaborates the role of Mucus in Fishes. Providing various patterns of colouration is one of the important tasks of the integument and ‘Fishes’ are often appreciated for their beautiful colourations, colour markings, spots etc.; particularly when a person is considering the entertainment value of aquarium fishes. For an Ichthyologist, the characteristic colouration of a fish becomes an important taxonomic character and for an Evolutionary Biologist it becomes a character of adaptive value (may be for concealment, advertisement, disguise/mimicry etc.). Bony fishes show the most brilliant and varied colourations as compared to cartilaginous fishes. The colour-related various aspects like structural colouration, biochromes, chromatophores, physiological and morphological colour-changes, structural and biochemical factors involved in colour change, Biochemical events and pigment motility in different chromatophores, extrinsic and intrinsic factors for colour changes, functional aspects of colouration etc. are discussed in Chapter 7.
2021 (1st January): ‘Fish and Fisheries Monitoring and Management Systems’ forms the contents of ‘Part – 1’
Fish and Fisheries being a vast discipline includes a number of topics prescribed variously in the curriculum of Universities and institutes. To render the subject matter more interesting, absorbing and less voluminous, an idea was build-up to unveil the ‘Text’ in the form of a concise, topic-oriented ‘SERIES’ of ‘Fish & Fisheries Digest’. ‘Fish and Fisheries Monitoring and Management Systems’ forms the contents of ‘Part – 1’ of the SERIES, at the hands of the readers. Furthermore, some Appendices (with information relevant to the topic or otherwise) may also find place at the end of the said eBook ‘SERIES’. For the benefit of the ‘Competition-oriented’ (NET/JRF) students, a ‘Question Bank’ is placed at the end of each Topic of the SERIES.
2006: General and Applied Ichthyology (Fish and Fisheries), Published by S. Chand and Co., Delhi [for B.Sc. , M.Sc. and Competitive Examinations ] (reprinted 2008, 2010, 2013 & 2014). *Volume II of the same is underprint. General and Applied Ichthyology (Fish and Fisheries)