The Goby (Gobius unipunctatus), or, as it is more popularly termed, One-Spotted Goby, is frequently found inhabiting the same pool as the Blenny or the Rockling. The distinguishing character of this pretty creature is the black spot which is situated between the fifth and sixth ray of the first dorsal fin. Its length is usually about one, or one and a half inches; specimens have, however, sometimes been found on the shores of the Frith of Forth, that measured nearly three inches.
The colour of the Goby is very changeable. If the animal is labouring under excitement, its body assumes a deep brownish tint, approaching in some instances to black; this gives place to brown, drab, and even amber, or yellowish white.
The Goby possesses the power of attaching its body to any object by means of its ventral fins, which become united together in the form of a funnel.
Another species (Gobius bipunctatus), or Two-Spotted Goby, is generally found among the Fuci, in rocky situations. Its name is derived from a dark spot which is distinctly apparent on each side, near to the origin of the pectoral fin.
The head and upper part of the body is dark brown,—the under part of the head and belly white or pale drab.
Allusion has already been made to the peculiarity of the Gobies affixing their bodies to rocks or other substances, by means of a sucker formed by the junction of the ventral fins. The adhesive power in question, which this class of creatures possess, is very limited as compared with that which is exercised by the true sucker fishes, and especially by the members of a certain species, whose bodies are furnished with two distinct organs of adhesion.
The extraordinary adhesive powers of the Lump-Sucker, for instance, have been tested by several writers. One observer states, that a fish of moderate size has been known to suspend a weight of above 20 lbs., upon which it had accidentally fastened itself. Mr. Pennant says still more, for he has known that, in flinging a fish of this kind just caught into a pail of water, it fixed itself so firmly to the bottom, that, on taking it by the tail, the pail was lifted up, though it contained several gallons of water.
To descend from the largest to the smallest species, we arrive at the Montague Sucker-Fish, or, as it is sometimes called, the Diminutive Sucker, one of the most interesting little creatures to be met with at the sea-shore. At the coast near Edinburgh I have met with many specimens, equally well in the spring or winter season, as during the summer months. At such locality this species may therefore be pronounced common; yet it is comparatively unknown to most 'collectors' in the neighbourhood. Many, indeed, contend that my designation is erroneous. But having taken considerable pains to satisfy my mind upon the subject, I have no hesitation whatever in stating that the little fish in question is identical with that of the Montague Sucker.
Donovan, in his 'Natural History of British Fishes,'[19] was the first to illustrate and publish an account of this petite gem of ocean. His figures are copied from drawings made by Colonel Montague, who also furnished the description of the specimen delineated. With the important exception of the sucker—an organ of adhesion which is very nearly correct—the general appearance of the Diminutive Sucker-Fish as figured, is not at all satisfactory. Perhaps this is not to be wondered at, when we remember that the specimen from which the sketches were taken was very small indeed. Moreover, it was diaphanous, and is depicted as being principally transparent, spotted, and tinged with pink.
The Diminutive Sucker, in its adult state, is said to be from two to three inches in length; consequently Colonel Montague's first specimen must have been an extremely young one.