CUTANEOUS TASTE-BUDS IN COD

The distribution of cutaneous taste buds was determined quantitatively in larvae, juveniles and young adults of cod, using scanning electron microscopy. Changes in these distributions associated with developmen t were followed in laboratory reared fish. Taste buds were first seen on the snout and lips of cod at a total length of 8 mm, and on the bar bel at a length of 22 mm. The highest taste bud densities were seen at a length of around 90 mm, and subsequently declined on the barbel and pelvic fins with further growth. In these late 0-group fish, mean tas te bud densities over much of the head, e.g. throat, dentary and sides of the snout were <100 mm(-2). On the tip of the snout and the lips, mean densities were in the region of 350-400 mm(-2), while on projecti ng parts of the fish, especially the barbel, anterior naris flap and e xtremities of the fins, spot densities occasionally exceeded 1000 mm(- 2) at some sites. Mean taste bud diameter increased rapidly from 2.23 mu m +/- 035 mu m (S.D.) at a length of 22 mm to 7.19 +/- 0.23 mu m at 90 mm length, with a much slower increase to about 8 mu m associated with a further doubling in body length. These changes indicate a phase of rapid proliferation and growth in size of cutaneous taste buds in the period preceding the adoption of a benthic habit in their first su mmer. The presence of high taste bud densities on the barbel and pelvi c fins in particular appears to correlate with the known feeding behav iour of cod. (C) 1998 The Fisheries Society of the British Isles.