Notoscopelus caudispinosus anal fin and 11 to 13 in the pectoral fins. There are groups of photophores (small light organs) on the head and sides of the body. Above the caudal peduncle there is a row of eight to nine luminous scale-like segments in adult males, but male fish lack luminous organs above the eye and on the cheek. "N. caudispinosus" differs from closely related species in having fewer than 15 gill rakers. This species has a wide oceanic distribution in deep water habitats. It is found in the eastern Atlantic Ocean between the equator and about 35°N, but is absent from
Operculum (gastropod) Operculum (gastropod) The operculum, meaning little lid, (plural: opercula or operculums) is a corneous or calcareous anatomical structure like a trapdoor which exists in many (but not all) groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc. The operculum is attached to the upper surface of the foot and in its most complete state, it serves as a sort of "trapdoor" to close the aperture of the