Flat needlefish
Encyclopedia
The flat needlefish, Ablennes hians, the only known member
of the genus
Ablennes, is a marine fish
of the family
Belonidae. Flat needlefish are considered gamefish, frequently caught with the help of artificial lights, but are not often eaten because of their green-colored flesh.
, they do have several soft rays. There are 23-26 rays on the dorsal fin
and 24-28 on the anal. They have 86-93 vertebrae. Dorsally, flat needlefish are blueish, white ventrally, with dark blotches and 12-14 vertical bars in the middle of the body. Flat needlefish have an elongated body, with scythe
-shapedpectoral, and anal fins. They also have a dark lobe on the posterior part of their dorsal fins. The longest recorded flat needlefish measured 140 cm long, Measurements for flat needlifish body length do not include caudal fin and head because the fish's long jaw
s are often broken off. The largest recorded weight for a flat needlefish was 4.8kg
.
seas
. In the Eastern Atlantic, they are known from Cape Verde
and Dakar
to Moçamedes
in Angola
. In the western Atlantic they are known from Chesapeake Bay
south to Brazil
. They are found throughout the Indian Ocean
, and in the western Pacific from the southern island
s of Japan
to Australia
and Tuvalu
.
Flat needlefish usually live in neritic ocean waters near island
s, estuaries, and near coastal river
s where they feed on smaller fish and occasionally gather in large schools
.
, which attach themselves to floating debris via filaments on the surface of each egg Only the left gonad in both sexes is developed, and in males, the right gonad is sometimes wholly absent.
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Ablennes, is a marine fish
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...
of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Belonidae. Flat needlefish are considered gamefish, frequently caught with the help of artificial lights, but are not often eaten because of their green-colored flesh.
Description
Although they have no spineSpine (zoology)
A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin...
, they do have several soft rays. There are 23-26 rays on the dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
and 24-28 on the anal. They have 86-93 vertebrae. Dorsally, flat needlefish are blueish, white ventrally, with dark blotches and 12-14 vertical bars in the middle of the body. Flat needlefish have an elongated body, with scythe
Scythe
A scythe is an agricultural hand tool for mowing grass, or reaping crops. It was largely replaced by horse-drawn and then tractor machinery, but is still used in some areas of Europe and Asia. The Grim Reaper is often depicted carrying or wielding a scythe...
-shapedpectoral, and anal fins. They also have a dark lobe on the posterior part of their dorsal fins. The longest recorded flat needlefish measured 140 cm long, Measurements for flat needlifish body length do not include caudal fin and head because the fish's long jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
s are often broken off. The largest recorded weight for a flat needlefish was 4.8kg
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
.
Distribution and habitat
Flat needlefish are found worldwide in tropical and temperateTemperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
seas
Seas
Seas may mean:*The plural of "sea"*Shipboard Environmental Acquisition System: a program developed by National Oceanic and Atmospheric Administration to provide accurate meteorological and oceanographic data in real time from ships at sea through the use of satellite data transmission...
. In the Eastern Atlantic, they are known from Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
and Dakar
Dakar
Dakar is the capital city and largest city of Senegal. It is located on the Cap-Vert Peninsula on the Atlantic coast and is the westernmost city on the African mainland...
to Moçamedes
Moçamedes
Moçâmedes may refer to:*Moçâmedes, was the name of a region and its chief city in the Portuguese Overseas Province of Angola, the present-day Namibe province and city, in South-Western Angola....
in Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...
. In the western Atlantic they are known from Chesapeake Bay
Chesapeake Bay
The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West...
south to Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. They are found throughout the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, and in the western Pacific from the southern island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...
s of 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...
to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and Tuvalu
Tuvalu
Tuvalu , formerly known as the Ellice Islands, is a Polynesian island nation located in the Pacific Ocean, midway between Hawaii and Australia. Its nearest neighbours are Kiribati, Nauru, Samoa and Fiji. It comprises four reef islands and five true atolls...
.
Flat needlefish usually live in neritic ocean waters near island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...
s, estuaries, and near coastal river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
s where they feed on smaller fish and occasionally gather in large schools
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
.
Reproduction
Flat needlefish lay eggsEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, which attach themselves to floating debris via filaments on the surface of each egg Only the left gonad in both sexes is developed, and in males, the right gonad is sometimes wholly absent.