Prowfish
Encyclopedia
Prowfish are subtropical perciform marine fish
found in the North Pacific
. They are the only member of their family, Zaproridae. They should not be confused with the Australian prowfish
of the unrelated family Pataecidae.
Prowfish range from the Aleutian Islands, Alaska
west to Kamchatka
, Russia
; from Navarin Canyon
in the Bering Sea
south to Hokkaidō
, Japan
and Monterey
, California
. An otherwise little-known species, prowfish are important to subsistence fisheries
in remote regions.
Growing to a length of 100 centimetres or more, prowfish have stout, laterally compressed and elongate bodies. They have a single, somewhat high dorsal fin running nearly the entire length of the back; it may contain 54-58 pliable spines. The anal fin is also fairly extensive. The tail fin is large, rounded and truncate; the pectoral fins are enlarged and pelvic fins are conspicuously absent. The mouth is slightly upturned with small, closely set sharp teeth confined to the jaws. The head is convex, ending in a projecting snout. This explains the family name Zaproridae; from the Greek
za, an intensifier, and prora meaning "prow." The species name silneus is a reference to Silenus
, a figure in Greek mythology
.
The distinctive head of the prowfish also features a number of sensory pores made all the more obvious by fringes of blue or white. Prowfish have small ctenoid scales and a variable coloration; typically they are bluish grey to olive brown with small dark spots, grading to lighter shades ventrally. The lateral line
and swim bladder are absent.
Thought to prefer rocky substrates in relatively shallow waters of no more than 675 metres, prowfish are benthic animals spending most of their time on or near the bottom. Their diet consists principally of scyphozoa
ns and salp
s; prowfish use their large mouths to tear chunks from the bells of jellyfish
and ctenophore
s. Prowfish may also eat smaller fish and amphipods; however, juveniles feed exclusively on jellyfish
. Larger skate
s and halibut
are known predators of prowfish.
Little is known of prowfish reproduction, but juveniles have been observed to be pelagic
; unlike adults, they spend their time in the mid levels of the water column, closely associated with their jellyfish prey. Indeed, juvenile prowfish will seek shelter from prey within the bells of larger jellies. This behaviour has led to their confusion with the medusafish
(Icichthys lockingtoni) of the family Centrolophidae. Most female prowfish are thought to reach maturity at c. five years. There is little sexual dimorphism
; females are slightly heavier for their length.
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
found in the North Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. They are the only member of their family, Zaproridae. They should not be confused with the Australian prowfish
Australian prowfish
Australian prowfishes are a family, Pataecidae, of scorpaeniform fishes. They are distinguished by a long dorsal fin that begins far forward on the head, forming a "prow" shape, and extends all the way to the caudal fin...
of the unrelated family Pataecidae.
Prowfish range from the Aleutian Islands, Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
west to Kamchatka
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
; from Navarin Canyon
Navarin Canyon
The Navarin Canyon is a submarine canyon in the Bering Sea. It is just as wide but less than half as deep as the Zhemchug Canyon, which is the largest canyon in the world....
in the Bering Sea
Bering Sea
The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves....
south to Hokkaidō
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and Monterey
Monterey, California
The City of Monterey in Monterey County is located on Monterey Bay along the Pacific coast in Central California. Monterey lies at an elevation of 26 feet above sea level. As of the 2010 census, the city population was 27,810. Monterey is of historical importance because it was the capital of...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. An otherwise little-known species, prowfish are important to subsistence fisheries
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
in remote regions.
Growing to a length of 100 centimetres or more, prowfish have stout, laterally compressed and elongate bodies. They have a single, somewhat high dorsal fin running nearly the entire length of the back; it may contain 54-58 pliable spines. The anal fin is also fairly extensive. The tail fin is large, rounded and truncate; the pectoral fins are enlarged and pelvic fins are conspicuously absent. The mouth is slightly upturned with small, closely set sharp teeth confined to the jaws. The head is convex, ending in a projecting snout. This explains the family name Zaproridae; from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
za, an intensifier, and prora meaning "prow." The species name silneus is a reference to Silenus
Silenus
In Greek mythology, Silenus was a companion and tutor to the wine god Dionysus.-Evolution of the character:The original Silenus resembled a folklore man of the forest with the ears of a horse and sometimes also the tail and legs of a horse...
, a figure in Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
.
The distinctive head of the prowfish also features a number of sensory pores made all the more obvious by fringes of blue or white. Prowfish have small ctenoid scales and a variable coloration; typically they are bluish grey to olive brown with small dark spots, grading to lighter shades ventrally. The lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
and swim bladder are absent.
Scyphozoa
Scyphozoa is a class within the phylum Cnidaria, sometimes referred to as the "true jellyfish".The class name Scyphozoa comes from the Greek word skyphos , denoting a kind of drinking cup and alluding to the cup shape of the organism....
ns and salp
Salp
A salp or salpa is a barrel-shaped, planktonic tunicate. It moves by contracting, thus pumping water through its gelatinous body...
s; prowfish use their large mouths to tear chunks from the bells of jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
and ctenophore
Ctenophore
The Ctenophora are a phylum of animals that live in marine waters worldwide. Their most distinctive feature is the "combs", groups of cilia that they use for swimming, and they are the largest animals that swim by means of cilia – adults of various species range from a few millimeters to in size...
s. Prowfish may also eat smaller fish and amphipods; however, juveniles feed exclusively on jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
. Larger skate
Skate
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. There are more than 200 described species in 27 genera. There are two subfamilies, Rajinae and Arhynchobatinae ....
s and halibut
Halibut
Halibut is a flatfish, genus Hippoglossus, from the family of the right-eye flounders . Other flatfish are also called halibut. The name is derived from haly and butt , for its popularity on Catholic holy days...
are known predators of prowfish.
Little is known of prowfish reproduction, but juveniles have been observed to be pelagic
Pelagic zone
Any water in a sea or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes...
; unlike adults, they spend their time in the mid levels of the water column, closely associated with their jellyfish prey. Indeed, juvenile prowfish will seek shelter from prey within the bells of larger jellies. This behaviour has led to their confusion with the medusafish
Medusafish
Medusafishes are a family, Centrolophidae, of perciform fishes. They are found in temperate and tropical waters throughout the world.Young Icichthys lockingtoni are abundant in the coastal waters of the north Pacific, where they are often found in association with jellyfish, which provides them...
(Icichthys lockingtoni) of the family Centrolophidae. Most female prowfish are thought to reach maturity at c. five years. There is little sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
; females are slightly heavier for their length.