A Guide to the Study of Fishes, Volume 2 (of 2)

by David Starr Jordan

The large-mouth black bass (Micropterus salmoides) is very much like the other in appearance. The mouth is larger, in the adult cleft beyond the eye; the scales are larger, and in the young there is always a broad black stripe along the sides and no cross-bands. The two are found in the same region, but almost never in the same waters, for the large-mouth bass is a fish of the lakes, ponds, and bayous, always avoiding the swift currents. The young like to hide among weeds or beneath lily-pads. From its preference for sluggish waters, its range extends farther to the southward, as far as the Mexican State of Tamaulipas.

Plioplarchus is a genus of fossil sunfishes from the Eocene of South Dakota and Oregon. Plioplarchus sexspinosus, septemspinosus, and whitei are imperfectly known species.

The Saleles: Kuhliidæ.—Much like the sunfishes in anatomy, though more like the white perch in appearance and habit, are the members of the little family of Kuhliidæ. These are active silvery perches of the tropical seas, ponds, and river-mouths, especially abundant in Polynesia. Kuhlia malo is the aholehole of the Hawaiians, a silvery fish living in great numbers in brackish waters. Kuhlia rupestris, the salele of the Samoan rivers, is a large swift fish of the rock pools, in form, color, and habits remarkably like the black bass. It is silvery bronze in hue, everywhere mottled with olive-green. The sesele, Kuhlia marginata, lives with it in the rivers, but is less abundant. The saboti, Kuhlia tæniura, a large silvery fish with cross-bands on the caudal fin, lives about lava-rooks in Polynesia from the Galapagos to Samoa and the East Indies, never entering rivers. Still other species are found in the rock pools and streams of Japan and southward.

The skeleton in Kuhlia is essentially like that of the black bass, and Dr. Boulenger places the genus with the Centrarchidæ.

The True Perches: Percidæ.—The great family of Percidæ includes fresh-water fishes of the northern hemisphere, elongate in body, with the vertebræ in increased number and with only two spines in the anal fin. About ninety species are recorded, the vast majority being American. The dwarf perches, called darters (Etheostominæ), are especially characteristic of the clear streams to the eastward of the plains of the Missouri. These constitute one of the greatest attractions of our American river fauna. They differ from the perch and its European allies in their small size, bright colors, and large fins, and more technically in the rudimentary condition of the pseudobranchiæ and the air-bladder, both of which organs are almost inappreciable. The preopercle is unarmed, and the number of the branchiostegals is six. The anal papilla is likewise developed, as in the Gobiidæ, to which group the darters bear a considerable superficial resemblance, which, however, indicates no real affinity.

Fig. 239.—Large-mouthed Black Bass, Micropterus salmoides (Lac.). (From life by Dr. R. W. Shufeldt.)

Relations of Darters to Perches.—The colors of the Etheostominæ, or darters, are usually very brilliant, species of Etheostoma especially being among the most brilliantly colored fishes known; the sexual differences are often great, the females being, as a rule, dull in color and more speckled or barred than the males. Most of them prefer clear running water, where they lie on the bottom concealed under stones, darting, when frightened or hungry, with great velocity for a short distance, by a powerful movement of the fan-shaped pectorals, then stopping as suddenly. They rarely use the caudal fin in swimming, and they are seldom seen floating or moving freely in the water like most fishes. When at rest they support themselves on their expanded ventrals and anal fin. All of them can turn the head from side to side, and they frequently lie with the head in a curved position or partly on one side of the body. The species of Ammocrypta, and perhaps some of the others, prefer a sandy bottom, where, by a sudden plunge, the fish buries itself in the sand, and remains quiescent for hours at a time with only its eyes and snout visible. The others lurk in stony places, under rocks and weeds. Although more than usually tenacious of vitality, the darters, from their bottom life, are the first to be disturbed by impurities in the water. All the darters are carnivorous, feeding chiefly on the larvæ of Diptera, and in their way voracious. All are of small size; the largest (Percina rex) reaches a length of ten inches, while the smallest (Microperca punctulata) is, one of the smallest spiny-rayed fishes known, barely attaining the length of an inch and a half. In Europe no Etheostominæ are found, their place being filled by the genera Zingel and Aspro, which bear a strong resemblance to the American forms, a resemblance which may be a clue to the origin of the latter.

The Perches.—The European perch, Perca fluviatilis, is placed by Cuvier at the head of the fish series, as representing in a high degree the traits of a fish without sign of incomplete development on the one hand or of degradation on the other. Doubtless the increased number of the vertebræ is the chief character which would lead us to call in question this time-honored arrangement. Because, however, the perch has a relatively degenerate vertebral column, we have used an allied form, the striped bass, as a fairer type of the perfected spiny-rayed fish. Certainly the bass represents this type better than the perch.

But though we may regard the perch as nearest the typically perfect fish, it is far from being one of the most highly specialized, for, as we have seen in several cases, a high degree of specialization of a particular structure is a first step toward its degradation.