Structure and ultrastructure study on photophores of the Madeira lanternfish, Ceratoscopelus maderensis (Lowe, 1839), Pisces: Myctophidae

Abstract

The structure and ultrastructure of photophores in the Madeira lanternfish, Ceratoscopelus maderensis, from the Strait of Messina (Mediterranean Sea) was investigated. The structure of C. maderensis photophore observed by light microscope consists of different functional parts: the photogenic cells, involved in the light production process, and a set of dioptric annexes, such as the accessory scales, lens-scale, reflector and pigmented layer. The photocytes have an elongated, thin and flattened shape and are located inside a cup-shaped structure, made up of the reflector and the pigmented layer. The lens-scale has a protection function as well as a dioptric role and is covered by accessory scales. The innervation of the lens-scale of C. maderensis and the other structures having a neurotransmitter function are probably implicated in the regulation of intensity and direction of light emission as well in playing a role in the counterillumination camouflage in the mesopelagic environment. The anatomical description of the photophores of C. maderensis provides a scientific basis for future investigations on the functioning of photogenic systems in relation to the ecology of this mesopelagic fish. K E Y W O R D S bioluminescence, Ceratoscopelus, lanternfish, photophores, structure, ultrastructure

Morphological, ultrastructural and immunohistochemical study on the skin ventral photophores of Diaphus holti Tåning, 1918 (Family: Myctophidae)

“…The morphological analysis of the lens confirms the dioptric role of this structure, as also found in other species of Myctophidae (Cavallaro et al, 2019). Furthermore, the lens seems to be involved in the collection of substrate for its chemical re-processing.…”

“…This study investigated for the first time the structure and ultrastructure of the photophore of the small lanternfish D. holti, confirming the glandular nature of its bioluminescence also found in other members of Myctophidae (Cavallaro et al, 2019;Denton, Herring, Widder, Latz, & Case, 1985;Edwards & Herring, 1977;Haygood, Edwards, Mowlds, & Rosenblatt, 1994;Lawry, 1973;Mallefet & Shimomura, 1995). However, unlike other lanternfish, that is C. maderensis (Cavallaro et al, 2019) annexes and glandular functional part, the photophore of D. holti showed some structural differences.…”

“…The morphological analysis confirmed the presence of the reflector and the pigmented layer in photophores oh D. holti, having a dioptric and protective function. A recent study on the lanternfish C. maderensis (Cavallaro et al, 2019) showed that in this species the reflector is arranged in different layers made up of bundles of parallel filaments and electrostatic material, with the presence of vacuoles in which, probably, are accumulate guanine grains with reflective function (Cavallaro et al, 2004). Differently, in D. holti the reflector is constituted by a thin pigmented layer, made up from a single bundle of thin dense and intricate filaments with melanin granules, which surrounds and covers its external surface.…”

“…Although the lanternfish ventral photophores show a similar structure at macroscopic scale, some differences between species were found trough microscopic analysis (Cavallaro et al, 2019). In the present study, we investigate the structure and ultrastructure of ventral photophores in Diaphus holti Tåning 1918, also providing some information on immunohistochemical aspects with regard to the photophore innervation.…”

Growth patterns of the lanternfish Ceratoscopelus maderensis in the western Mediterranean Sea

“…Ceratoscopelus maderensis (Lowe, 1839) is a lanternfish species (Myctophidae) that is generally found in mesopelagic waters at depths ranging from 200 to 1000 m between 50ºN and 30°N in the North Atlantic Ocean (Hulley 1984) and throughout the Mediterranean Sea (Jonsson 1992, Cavallaro et al 2019. Its larval stages inhabit the epipelagic layer, mostly concentrated in the first 50 m of the water column.…”