Stomiiformes ( Greek Stoma= mouth forma= shape)
Taxonomy: Superclass: Gnathostomata
Class: Actinopterygii (ray-finned fishes)
Order: Stomiiformes (dragonfishes and allies)
Families (4): Gonostomatidae (Bristlemouths), Phosichthyidae (Lightfishes),
Sternoptychidae (Marine hatchetfishes), Stomiddae (Barbeled dragonfishes)
50genera ~400 species VT Species : none
Description: Stomiiformes are teleost fishes with large mouths displaying large teeth on both the maxilla and premaxilla. The jaw can extent past the eye in some species. Photophores, luminescent organs, are usually present, scales are cycloid if present, dark in color and some are silvery. Pectoral, dorsal or adipose fins absent in some species, 4-9 pelvic fin rays, and 5-24 branchiostegal rays. Eyes tend to point upward.
Habitat: Tropical to temperate deep sea. Marine only. Most species are mesopelagic while others are bathypelagic. Water column migration is included in their habitat due to daily rituals.
Distribution : Wide distribution in the earths oceans. Ranging from tropic to temperate and subarctic to Antarctic regions.
Ecology and Life History During the day Stomiiformes stay in deep waters and at night migrate up the water column to hunt planktonic invertebrates and small fish. Stomiiformes reproduce by laying eggs in the deep sea. The larvae float in the pelagic water column toward the surface of the ocean. Once metamorphosed the juveniles descend down the water column to join the adults.
Some species have separate sexes others mature into males to produce sperm, and can later develop into females to produce eggs for younger males. Species with separate sexes, it is common for males to have smell organs to locate females.
Additional Details: All Stomiiformes but one have the ability to produce light from a mechanism called photophores. This organ or mechanism can be simple or as complex as shutters, color filters, reflectors and lenses. The light is produced by the specialized mitochondria cells called photocytes found during digestion. Some of the light producing cells are noted to be related to symbiotic bacteria. The ability to produce light benefits the Stomiiformes by attracting prey and confusing predators. The location of the photophores can vary amongst species for example
Stemoptychidae (marine hatchetfishes) have photophores under their eyes and along the underside of their body. The light produced can be yellow, violet, white or red.
Recent Research: Recent research has found a new species of Stemoptychidae (marine hatchetfishes) in the order of Stomiiformes. The new species Discosternon federicae was located in Italy near the town of Gessopalena. One specimen was taken with unique physiological features - loss of anal and dorsal fins, slender haemel spines and a reduction of supraneurals.
(Carnevale 2008). Discosternon has been declared a “miniature” fish and has a new unique feeding ecology compared to most Stomiiformes. It prefers mid-water plankton and is less likely to show signs of vertical migration within the water column.
References Used:
Bond, C. E. 1996. Biology of Fishes, 2 nd . ed. Saunders College Publishing, Fort Worth
Moyle, Peter 1982. Fishes An Introduction to Ichthyology 4 th ed. Prentice-Hall, Inc.
Carnevale, Giorgio 2008. Miniature deep-sea hatchetfish, Geological Magazine
Froese Ranier and Pauly Daniel, 2008. Stomiiformes, FishBase