The bareskin dogfish (Centroscyllium kamoharai) is a species of deepwater dogfish shark belonging to the family Etmopteridae, commonly known as lantern sharks. It is characterized by its exceptionally smooth, scaleless skin, which lacks the dermal denticles (placoid scales) typically found on sharks. This distinctive feature gives it its common name.
Etymology
- Bareskin: Refers to the species' most notable characteristic: the absence of dermal denticles over most of its body, making its skin appear smooth or "bare."
- Dogfish: A general term for many species of small to medium-sized sharks, particularly those in the order Squaliformes, often known for their slender bodies and habit of hunting in packs (though this behavior is not specifically documented for the bareskin dogfish).
- Centroscyllium kamoharai:
- Centroscyllium: Derived from Greek kentron (thorn, spine) and skyllion (a type of shark, possibly from skylle meaning to tear), referring to the spines typically found in front of its dorsal fins.
- kamoharai: Named in honor of Dr. Toshiji Kamohara, a distinguished Japanese ichthyologist who made significant contributions to the study of fish in Japan.
Description
The bareskin dogfish is a relatively small, slender deep-sea shark, typically reaching lengths of up to 47 cm (18.5 inches). Its most striking feature, as its name suggests, is the remarkable absence of dermal denticles (placoid scales) across nearly its entire body, giving its skin a smooth, almost gelatinous texture. Scattered, small denticles may be present only along the anterior edges of its dorsal fins.
Other key descriptive features include:
- Coloration: Uniformly dark brown to black over its entire body.
- Body Shape: A moderately robust body with a relatively short, blunt snout.
- Fins: It possesses two dorsal fins, each preceded by a grooved spine, a characteristic feature of many dogfish sharks. The pectoral fins are small, and it lacks an anal fin.
- Photophores: Unlike many other lantern sharks in the Etmopteridae family that are highly bioluminescent, C. kamoharai has very few, indistinct photophores (light-producing organs), primarily restricted to the ventral surface of the head and around the cloaca.
Habitat and Distribution
The bareskin dogfish is a bathydemersal (bottom-dwelling in deep waters) or benthopelagic (living near the bottom but also swimming in the open water column) species. It inhabits the deep waters of the western Pacific Ocean. Its known distribution primarily includes the seas around Japan, particularly off Tosa Bay, and the Okinawa Trough. It has been recorded at depths ranging from approximately 500 to over 1,000 meters (1,640 to 3,280 feet).
Biology and Ecology
Due to its deep-sea habitat and rarity of encounters, specific details about the biology and ecology of the bareskin dogfish are limited.
- Diet: Like other deep-sea dogfish, it is presumed to be a predator, feeding on small deep-sea invertebrates and bony fishes.
- Reproduction: It is thought to be ovoviviparous, a common reproductive strategy among dogfish sharks, where eggs hatch inside the mother's uterus, and live young are born after developing internally.
- Behavior: Little is known about its social behavior, migration patterns, or specific feeding strategies.
Conservation Status
The International Union for Conservation of Nature (IUCN) currently lists the bareskin dogfish as Data Deficient (DD). This classification reflects the scarcity of information available on the species. It is rarely encountered in scientific surveys or commercial fisheries, making it difficult to assess its population size, trends, or specific threats. Deep-sea species are generally vulnerable to overfishing when they occur in areas targeted by deep-sea trawlers, but the direct impact on Centroscyllium kamoharai is currently unknown. Further research is needed to determine its conservation needs.