Tastebuds and unculi: The sensing and anchoring systems of torrential ichthyofauna

Abstract

Ultrasurface structure of the oromandibular area of hillstream fishes Amblyceps arunachalense Nath & Dey, 1989; Glyptothorax trilineatus Blyth, 1860; Balitora brucei Gray, 1830; Psilorhynchus balitora (Hamilton, 1822), Tariqilabeo latius (Hamilton, 1822); Garra gotyla (Gray, 1830); Pseudolaguvia ferula Ng, 2006; and Pseudolaguvia shawi (Hora, 1921) collected from the Ranganadi river, a northern tributary of the river Brahmaputra of Assam is described in the current investigation. Scanning electron microscopic (SEM) study of the oromandibular areas of these fishes revealed the presence of a series of punctuation elevation from the general body surface known as the tastebuds (TBs) responsible for chemoreception, mechanoreception and thermo sensing activities. In B. brucei, A. arunachalense and G. trilineatus; the TBs were found to have two types of microvillar projections which confirm to the characteristics of type II TBs or the light cells while type III TBs or intermediate cells were seen in P. balitora. Dark cells (type I) were not recorded in the fishes under this investigation. Another type of cell, the basal cells, without any apical microvilli, was also recorded on the surface of all the fishes. Several mucous pores were also recorded which secrete mucous that protect the fishes from desiccation and drying.

Different shaped unculi and breeding tubercles were recorded from B. brucei; P. balitora; T. latius; G. gotyla; P. ferula, and P. shawi which were found to be helpful during anchorage to the rocky substratum (Roberts, 1982).