Trygonorrhina
Encyclopedia
The fiddler rays or banjo sharks are a genus
, Trygonorrhina, of guitarfish
, family Rhinobatidae. There are two species, found along the eastern and southern coasts of Australia
. They are benthic
in nature, favoring shallow sandy bays, rocky reef
s, and seagrass
beds. The eastern fiddler is found to a depth of 120 meters and the southern fiddler to a depth of 180 meters.
The flattened pectoral fin discs of fiddler rays are shorter and more rounded than that of other guitarfishes. Their tails are slender, with a well-developed caudal fin and two triangular dorsal fin
s. Their snouts are translucent. The fiddler rays are also distinguished from other guitarfishes in that the anterior nasal flaps of their nostril
s are expanded backwards and fused together into a nasal curtain that reaches the mouth.
Fiddler rays feed on bottom shellfish
, crab
s, and worm
s, which they crush between their jaw
s. The eastern fiddler ray is known to scavenge
from fish trap
s. Like other guitarfishes, fiddler rays are ovoviviparous
. The egg
capsules of the southern fiddler ray are reported to be golden in color, containing three embryo
s each. It gives birth to litters of 4-6 young per breeding cycle. Fiddler rays are harmless and easily approached by divers. Southern fiddler rays are taken as bycatch
by commercial trawlers and by recreational fishers
; the flesh is of good quality and sold in small quantities.
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...
, Trygonorrhina, of guitarfish
Guitarfish
The guitarfish are a family, Rhinobatidae, of rays. The guitarfish are known for an elongated body with a flattened head and trunk and small ray like wings. The combined range of the various species is tropical, subtropical and temperate waters worldwide. They often travel in large...
, family Rhinobatidae. There are two species, found along the eastern and southern coasts of 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...
. They are benthic
Benthic zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...
in nature, favoring shallow sandy bays, rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s, and seagrass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...
beds. The eastern fiddler is found to a depth of 120 meters and the southern fiddler to a depth of 180 meters.
The flattened pectoral fin discs of fiddler rays are shorter and more rounded than that of other guitarfishes. Their tails are slender, with a well-developed caudal fin and two triangular 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...
s. Their snouts are translucent. The fiddler rays are also distinguished from other guitarfishes in that the anterior nasal flaps of their nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s are expanded backwards and fused together into a nasal curtain that reaches the mouth.
Fiddler rays feed on bottom shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, and worm
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
s, which they crush between their 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. The eastern fiddler ray is known to scavenge
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
from fish trap
Fish trap
A fish trap is a trap used for fishing. Fish traps may have the form of a fishing weir or a lobster trap. A typical trap might consist of a frame of thick steel wire in the shape of a heart, with chicken wire stretched around it. The mesh wraps around the frame and then tapers into the inside of...
s. Like other guitarfishes, fiddler rays are ovoviviparous
Ovoviviparity
Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...
. The egg
Egg (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...
capsules of the southern fiddler ray are reported to be golden in color, containing three embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s each. It gives birth to litters of 4-6 young per breeding cycle. Fiddler rays are harmless and easily approached by divers. Southern fiddler rays are taken as bycatch
Bycatch
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 commercial trawlers and by recreational fishers
Recreational fishing
Recreational fishing, also called sport fishing, is fishing for pleasure or competition. It can be contrasted with commercial fishing, which is fishing for profit, or subsistence fishing, which is fishing for survival....
; the flesh is of good quality and sold in small quantities.
Species
- Southern fiddler ray, Trygonorrhina fasciata J. P. MüllerJohannes Peter MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
& HenleFriedrich Gustav Jakob HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1841 This species occurs along the southern coast of AustraliaAustraliaAustralia , 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...
. It is brown with shades of yellow or olive above, with a pattern of pale lilac bands edged with dark brown and a distinctive triangular pattern behind its eyes. It has been split into an eastern (fasciata) and western (dumerilii) form which is darker yellowish brown color than the eastern form, with blue-grey bands that do not form a triangle behind the eyes. However, the two are currently considered conspecific with T. dumerilii (Castenlau, 1873) considered a junior synonym of T. fasciata. This species reaches a length of 126 cm.
- Magpie fiddler ray, Trygonorrhina melaleuca T. Scott, 1954 A very rare species known only from Gulf St Vincent in South AustraliaSouth AustraliaSouth Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
, distinguishable by its entirely bluish-black coloration. It may represent a mutantMutantIn biology and especially genetics, a mutant is an individual, organism, or new genetic character, arising or resulting from an instance of mutation, which is a base-pair sequence change within the DNA of a gene or chromosome of an organism resulting in the creation of a new character or trait not...
form of the southern fiddler ray.