Histostructure of the Locomotor Apparatus in the Three Deep-Water Species of Lanternfishes (Myctophidae): Myctophum punctatum, Notoscopelus kroyeri, and Lampanyctus macdonaldi

Abstract

The morphological and functional characteristics of the somatic musculature’s histological structure have been studied for three species of deep-sea fish from the Myctophidae family: spotted lanternfish Myctophum punctatum, lancet fish Notoscopelus kroyeri, and rakery beaconlamp Lampanyctus macdonaldi. The average diameter of fast-twitch and slow-twitch muscle fibers in all studied species is large, and this indicator is highest in rakery beaconlamp. All species are characterized by a craniocaudal gradient of a decrease in the size of white muscle fibers. The shape of the fibers, from angular polygonal (spotted lanternfish) to the oval (rakery beaconlamp) and round (lancet fish), is a distinctive feature from other species of bony fish. In spotted lanternfish, a group of fibers of very small diameter, which are presumably small, slow-twitch oxidizing fibers, was also noted between the white and red muscles. The red muscles in the studied fish are poorly identified, since they are poorly developed. The studied species have a well-developed connective tissue carcass of white muscles, which indicates a certain friability of fast-twitch muscles. Both the red and white muscles in lanternfishes are a place of intense deposition of lipid reserves. Apparently, the high lipid content in muscle tissue helps to reduce the specific gravity of fish and increase their buoyancy.