Capros rhenanus Weiler, 1920, a Boarfish

Capros rhenanus Weiler, 1920

Middle Oligocene

Menilite Beds

Carpathian Mountains

St. Bircza

Poland

This species belongs to a small family of marine ray-finned fishes, the Caproidea (Boarfish, Capros = boar from the Greek kapros). The family consists of about 12 species in two genera, all of them deep-sea types: Antigona and Capros (monotypic).

Caproidea are characterized by usually thin and deep, compressed, and oblong to disk-shaped bodies with 5 -10 soft rays and possibly a spine in the pelvic fins, 5 -10 dorsal fin spines and up to 4 anal fin spines. The upper jaw with minute, slender conical teeth is more or less protrusible. With their greatly compressed head and body, large mouth, and extremely protrusible upper jaw, the Zeiformes are successful ambush predators. They slowly approach an unsuspecting small fish by means of undulating waves of the transparent soft dorsal and anal fins. In one quick motion they drop the "trapdoor" lower jaw, shoot out the upper jaw, and expand the gill cavity, sucking in the hapless prey along with a considerable volume of water. Caproidea fishes are carnivores; they feed mainly on a variety of fishes but also consume cephalopods and crustaceans.

This fish here is a Capros rhenanus from the menilite shales of Bircza in the Polish Carpathians. All members of the genus Capros are characterized by a laterally compressed body that is as high as it is long. Fishes of this genus typically have three spines and five soft rays in the anal fin. The pectoral fins are rounded, the pelvic fins set below them (1 stout spine and 5 slightly softer finrays). The first dorsal fin consists of about nine to ten spikes, the second dorsal fin has 23 to 25 soft finrays. The large eye is well suited to its habitat in deep marine waters ranging from 40m to 600m. The protractile mouth, forming a small tube when protruded, is perfect for catching small copepods, mysids, benthic crustaceans and worms. The living species are all characterized by red coloration.