Longtail butterfly ray
Encyclopedia
The longtail butterfly ray, Gymnura poecilura, is a species
of butterfly ray
, family Gymnuridae. It has a wide but apparently non-continuous distribution in the Indo-West Pacific
, occurring in the Red Sea
, Somalia
, and Oman
, and from Pakistan
to Indonesia
to southern Japan
. There is also an isolated population in French Polynesia
. Its presence is unconfirmed between Oman and Pakistan. It is found over sand
y or mud
dy bottoms in shallow inshore waters or offshore banks to a depth of 30 m.
This species is distinguishable from other butterfly rays in that the distance from the tip of its snout
to its cloaca
is the same as that from the cloaca to the tip of its tail
. Its body has the characteristic shape of the butterfly rays, with a pectoral fin disc twice as wide as it is long. The front margin of the disc has a slight sinuous curve, the rear margin is convex, and the tips are little rounded. The snout
has a small, pointed projection at the tip. There are no dorsal
or caudal fins, and there is a small venom
ous spine at the base of the tail. The disc is light brown above with small white spots and sometimes scattered small dark brown spots. The tail has 8-9 each of alternating black and white rings, the white with a small dark dorsal spot (sometimes only on bands near the tail base). The maximum known disc width is 91.5 cm.
The diet of the longtail butterfly ray includes fish
es (especially Leiognathus), molluscs, and crustacean
s. It is ovoviviparous, with a maximum fecundity
of seven young. There is apparently no relationship between fecundity and female size, although this information may be confounded by the fact that females often spontaneously abort young upon capture. Breeding takes place year-round, with parturition peaking between April and October. This species is targeted by artisanal fisheries
in India
, Thailand
and Indonesia
, where it is utilized for human consumption. It is also taken as by-catch
by fisheries in other parts of its range. Due to its low fecundity, restricted habitat, and susceptibility to exploitation, the longtail butterfly ray was assessed as Near Threatened in the IUCN Red List
pending more concrete population and capture data.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of butterfly ray
Butterfly ray
The butterfly rays are a group of rays forming the genus Gymnura and the family Gymnuridae. They are found in warm oceans worldwide, and occasionally in estuaries....
, family Gymnuridae. It has a wide but apparently non-continuous distribution in the Indo-West Pacific
Indo-West Pacific
The Indo-West Pacific, or IWP, is a zoogeographical region spanning the entire Indian Ocean including the Red Sea and the Pacific Ocean as far as the Caroline Islands but short of the Marshall Islands...
, occurring in the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
, Somalia
Somalia
Somalia , officially the Somali Republic and formerly known as the Somali Democratic Republic under Socialist rule, is a country located in the Horn of Africa. Since the outbreak of the Somali Civil War in 1991 there has been no central government control over most of the country's territory...
, and Oman
Oman
Oman , officially called the Sultanate of Oman , is an Arab state in southwest Asia on the southeast coast of the Arabian Peninsula. It is bordered by the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest. The coast is formed by the Arabian Sea on the...
, and from Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
to Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
to southern 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...
. There is also an isolated population in French Polynesia
French Polynesia
French Polynesia is an overseas country of the French Republic . It is made up of several groups of Polynesian islands, the most famous island being Tahiti in the Society Islands group, which is also the most populous island and the seat of the capital of the territory...
. Its presence is unconfirmed between Oman and Pakistan. It is found over sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
y or mud
Mud
Mud is a mixture of water and some combination of soil, silt, and clay. Ancient mud deposits harden over geological time to form sedimentary rock such as shale or mudstone . When geological deposits of mud are formed in estuaries the resultant layers are termed bay muds...
dy bottoms in shallow inshore waters or offshore banks to a depth of 30 m.
This species is distinguishable from other butterfly rays in that the distance from the tip of its snout
Snout
The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...
to its cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
is the same as that from the cloaca to the tip of its tail
Tail
The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...
. Its body has the characteristic shape of the butterfly rays, with a pectoral fin disc twice as wide as it is long. The front margin of the disc has a slight sinuous curve, the rear margin is convex, and the tips are little rounded. The snout
Snout
The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...
has a small, pointed projection at the tip. There are no dorsal
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...
or caudal fins, and there is a small venom
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
ous spine at the base of the tail. The disc is light brown above with small white spots and sometimes scattered small dark brown spots. The tail has 8-9 each of alternating black and white rings, the white with a small dark dorsal spot (sometimes only on bands near the tail base). The maximum known disc width is 91.5 cm.
The diet of the longtail butterfly ray includes 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...
es (especially Leiognathus), molluscs, and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s. It is ovoviviparous, with a maximum fecundity
Fecundity
Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...
of seven young. There is apparently no relationship between fecundity and female size, although this information may be confounded by the fact that females often spontaneously abort young upon capture. Breeding takes place year-round, with parturition peaking between April and October. This species is targeted by artisanal fisheries
Artisan fishing
Artisan fishing is a term used to describe small scale low-technology commercial or subsistence fishing practices. The term particularly applies to coastal or island ethnic groups using traditional techniques such as rod and tackle, arrows and harpoons, throw nets and drag nets, and traditional...
in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, where it is utilized for human consumption. It is also taken as by-catch
By-catch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
by fisheries in other parts of its range. Due to its low fecundity, restricted habitat, and susceptibility to exploitation, the longtail butterfly ray was assessed as Near Threatened in the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
pending more concrete population and capture data.