The fishes belonging to this family are of large size and compact shape, with the anterior part of the body greatly expanded. The head, which is broad, bears venomous spines, and the mouth is furnished with large teeth. These fishes are voracious, and lie in wait for their prey at the bottom of the water in the mud of the shore. In order to attract it, they make use of cutaneous appendages attached to their spines, which they are able to elevate, and of filaments situated near the mouth.
The principal genus is Lophius, one species of which, L. setigerus ([fig. 112]), is found in the seas of China and Japan. Another species, L. piscatorius (the Sea Devil or Angler), occurs in the temperate climates of Europe, North America, Asia and Africa.
Certain other Acanthopterygii are capable of inflicting wounds, but, although fishermen often believe them to be venomous, or such properties are frequently attributed to them in stories, it is doubtful whether they possess poison-glands. The accidents produced by them are due rather to the fact that the spines in their fins are extremely sharp, and that their flesh is toxic. Those belonging to the Percidæ (the Perch family), especially the genus Serranus and S. ouatabili ([fig. 113]) in particular, are above all remarkable in this respect. The last-mentioned fish has two or three spines on its operculum.
Fig. 113.—Serranus ouatabili. (After Savtschenko.)
The same may be said of certain Squamipinnes, another family of Acanthopterygii, whose stout bodies are brightly coloured, and have very sharp, spiny rays in their dorsal and anal fins. The most curious genus among the fishes belonging to this family is Holacanthus, in which the præoperculum is provided with an enormous spine like that of the Weever. Holocanthus imperator ([fig. 114]) is met with fairly often in the Indian Ocean and Malay Archipelago.
Fig. 114.—Holacanthus imperator (Indian Ocean and Malay Archipelago). (After Savtschenko.)
B.—Teleostei.—Plectognathi.
The Order Plectognathi (Family Gymnodontes) includes the genera Diodon, Tetrodon and Triodon, globular fishes, in which the jaw is transformed into a beak and furnished with a sharp dentary plate. Their œsophagus is dilated into a resonant air-pouch. When removed from the water they swallow air and dilate the pouch, and the expulsion of this air is accompanied by a loud noise.