Viscous Property of Epidermal Mucous Cells of Burrowing Snake Eel - A Histochemical Analysis

The secretion of mucus is a characteristic feature of almost all teleost fish. Mucus is a slimy, viscous, sticky substance at the surface of the skin, produced mainly by the epidermal unicellular mucous cells. The epidermal mucus is important to fish in several ways. The main function is to give protection to the animal from various pathogens and predators. The lubricating properties of mucus assist in locomotion, and also protect the animal from abrasion during burrowing. Mucus facilitates cutaneous respiration, coagulates heavy metal salts in polluted waters and plays a role in osmoregulation. Mucus also plays a role during breeding season in constructing nests and thereby supporting eggs and young ones. Thus, the epidermal mucus is involved in protection, locomotion and homeostasis of fish. It is well-known that the epidermal mucous secretions are valuable to mankind. The mucus secreted by Ophiocephalus provided extra strength to mortar and was used for the construction of old churches in Cochin. The epidermal mucous secretion of ophuroid Opiocomina nigra and the mucus and meat of the clam, Spisula solidissima were shown to contain highly sulphated mucopolysaccharides and hence possess heparin-like anticoagulant property. The secretory contents of mucous cells of some fishes were identified as sulphated acid mucopolysaccharides. It is worth isolating the sulphated mucopolysaccharides and purifying the heparin-like component. Fish skin mucus were identified to contain toxin for defensive purpose. It also possesses a remarkable power of coagulating and precipitating mud held in suspension in water. This behavior of mucus is similar to that of the commercial fertilizers, manure, sludge and other organic matter which have been used to clear turbid waters in ponds.