A study of the correlation between the feeding habits and the structure of the hind brain in the South Indian cyprinoid fishes

Abstract

The cyprinoids, according to their feeding habit, can be divided into 2 main groups (1) Fishes which feed by taste. These are bottom feeders and possess small eyes; they can be subdivided into: (a) Fishes that feed by mouth taste, e.g., Lepidocephalichthys takes mud directly into the mouth where the palatal organ (closely packed taste buds in pharynx) sorts out food from other substances. The palatal organ is innervated by n. X, and hence there is a very prominent development of the vasal lobes in this fish. The facials are small. (b) Fish that use their barbels to sort out food, e.g., Nemachilus and Nemachilichthys, which grope and grub for food on the bottom. The taste buds on the barbels are innervated by n. VII and consequently the facial lobe is highly developed. The facial nerve is divided into, generally, 2 branches after entering the brain. The vagal lobes are small. (2) Fishes that feed largely by sight, e.g., Rasbora, Nauria, Danio, and Chela. They feed near the surface mainly on Crustacea and insects. The eyes are large and the mouth is directed upwards. Barbels are absent or vestigial. These fishes possess a well developed central acoustic lobe. Both the vagal and the facial lobes are very small.