GOBIES IN THE UPPER BLACKWATER ESTUARY 123
Figure 2 Ventral view of a 'goby' showing the structure of the pelvic sucker.
and Table 2 lists some meristic characters which can be used in the labora-
tory. Figure 3 gives outlines of the gobies considered below, with the
'field' distinguishing features mentioned in the text indicated.
Pomatoschistus microps: The Common Goby is an estuarine fish able to
withstand a range of salinities from fresh-water to sea-water. It is a shallow-
water fish frequently found in pools and at the very edge of the water
(Nyman, 1953: Jones and Miller, 1956), although in cold weather the fish
will migrate short distances to deeper water. The fish is generally dark grey,
although it will become light brown on a sandy substrate. It has about ten
dark spots along its flanks (Figure 3:A). These are of uniform size and
intensity. The dorsal and anal fins are banded. There is a dark flash on the
top half of the base of the pectoral fin (B) and two dark stripes running
down and forward from the eye (C). The caudal peduncle (D) is long and
the tail (E) is relatively deeper than that of the Sand Goby. In spring and
summer the nuptial colours of the male are very distinct. The general
colouring becomes very much darker, giving the fish a dark smoky appear-
ance and a prominent blue spot appears on the first dorsal fin.
Table 2
Some meristic characters used when defining the species mentioned
in the text (from Wheeler, 1969)
(a) Stiff, unbranched rays in the fin, designated by roman numerals.
(b) Branched, flexible rays, designated by arabic numerals.
(c) Number of scales along the lateral line, beginning at the upper edge of the
gill covers.