Masked stingaree
Encyclopedia
The masked stingaree (Trygonoptera personata) is a common species
of stingray
in the family
Urolophidae, endemic to southwestern Australia
. It prefers moderately deep areas of sand or seagrass
some distance from shore, though it can be found in very shallow water or to a depth of 115 m (377.3 ft). The masked stingaree can be identified by the two large, dark blotches on the upper surface of its rounded pectoral fin disc, one of which encompasses its eyes like a mask. The outer rims of its nostrils are expanded into prominent lobes, while between the nostrils is a skirt-like curtain of skin with a deeply fringed trailing margin. Its tail bears a small dorsal fin
just before the stinging spine, and end in a leaf-like caudal fin. This species grows up to 31 cm (12.2 in) across.
The diet of the masked stingaree consists primarily of polychaete worms and crustacean
s, with a general shift from the latter to the former as the ray ages. It is aplacental viviparous, with females typically bearing one pup annually and nourishing it with histotroph ("uterine
milk"). The 10–12 month long gestation period
consists of a five month period of suspended development
for the egg, followed by rapid growth of the embryo
and birthing in late April or early May. The International Union for Conservation of Nature (IUCN) has listed the masked stingaree under Least Concern
. Fishing pressure on this species is largely limited to a small number of scallop
and prawn
trawlers. Most such incidental capture
s result in the ray being released alive, though it does have a tendency to abort any unborn young during capture.
personatus, meaning "masked") in reference to its distinctive coloration. A male 23 cm (9.1 in) across was designated as the type specimen; it was collected by the research trawler FRV Hai Kung from northeast of Cape Naturaliste
in Western Australia
on 23 April 1981.
to Geographe Bay
, the masked stingaree is one of the most abundant representatives of its family within its range, particularly in the south. This bottom-dwelling ray has been reported from the shore to a depth of 115 m (377.3 ft) on the continental shelf
, and seems to be most common in offshore waters 20–35 m (65.6–114.8 ft) deep. It favors sandy flats and seagrass
beds. There is no evidence of segregation by age or sex, or of seasonal migration
s.
s with angular posterior rims. The outer margin of each nostril is enlarged into a broad, flattened lobe. Between the nostrils is a skirt-shaped curtain of skin with a fringed trailing margin, that conceals the small mouth. The lower jaw bears a patch of subtle papillae (nipple-shaped structures); there are also 3–4 papillae on the floor of the month. The small teeth have roughly oval bases. The five pairs of gill slit
s are short.
The pelvic fins are small with rounded margins. The tail measures 67–86% as long as the disc; it has an oval cross-section and is slightly flattened at the base. There is a single serrated stinging spine on the upper surface of the tail, which is immediately preceded by a rather large dorsal fin
. The tail ends in an elongated, leaf-shaped caudal fin, and lacks lateral fin folds. The skin is devoid of dermal denticles. The masked stingaree has an ochre to gray dorsal coloration with two large, distinctive dark blotches, one forming a "mask" around the eyes and the other at the center of the disc; these blotches may be connected by thin lines along the midline and on either side. The underside is white, becoming darker at the fin margins. The dorsal and caudal fins are black in young rays, and fade to gray in adults. Males and females grow up to 27 cm (10.6 in) and 31 cm (12.2 in) across respectively.
s are the predominant sources of food for the masked stingaree; on occasion sipunculid worm
s, molluscs, and echinoderm
s are also taken. This species preys on both sedentary polychaetes, which generally inhabit deeply buried tubes, and on errant polychaetes, which are generally more mobile and shallowly buried. The expanded lobes and sensory papillae adjacent to its mouth likely aid in locating and excavating such burrowing prey. Young rays feed mainly on crustaceans, including mysids
, amphipods, cumacea
ns, tanaids
, and shrimp
. With age polychaetes are added to the diet; sedentary polychaetes are significant to rays 13–29 cm (5.1–11.4 in) across, while errant polychaetes become progressively more important such as that the largest rays eat little else.
Like other stingrays, the masked stingaree is aplacental viviparous. Females have a single functional uterus
(the left) and produce a single pup (rarely two) per year. Ovulation
and mating
occur from mid-June to mid-July; fertilized eggs are enclosed by a delicate brown capsule and maintained in a state of diapause
(dormancy
) within the uterus until November. Afterward the embryo
s develop rapidly and are sustained by nutrient
-rich histotroph ("uterine milk") produced by the mother; an average embryo increases in disc width from 1.1 cm (0.433070866141732 in) in December to 11 cm (4.3 in) in April, to be born in late April or early May at a disc width of 13 cm (5.1 in). The total gestation period
, including diapause, lasts 10–12 months. Females grow more slowly and to a larger ultimate size than males. Males mature sexually
at around 22 cm (8.7 in) across and females at 23 cm (9.1 in) across; both sexes mature on average at four years of age. The maximum lifespan is 10 years for males and 16 years for females.
and prawn
trawl fisheries operating off Perth
and Mandurah regularly take the masked stingaree as bycatch
, though only a small number of vessels are involved. This ray may also be caught incidentally by small-scale fisheries further north, though overall it does not face substantial fishing pressure. When caught, the masked stingaree usually survives to be discarded, though the tendency of captured stingarees to abort their young merits concern. Given the limited conservation threats faced by this common species, the International Union for Conservation of Nature (IUCN) has listed it under Least Concern
. This species would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.
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 stingray
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
in 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...
Urolophidae, endemic to southwestern 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...
. It prefers moderately deep areas of sand or 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:...
some distance from shore, though it can be found in very shallow water or to a depth of 115 m (377.3 ft). The masked stingaree can be identified by the two large, dark blotches on the upper surface of its rounded pectoral fin disc, one of which encompasses its eyes like a mask. The outer rims of its nostrils are expanded into prominent lobes, while between the nostrils is a skirt-like curtain of skin with a deeply fringed trailing margin. Its tail bears a small 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...
just before the stinging spine, and end in a leaf-like caudal fin. This species grows up to 31 cm (12.2 in) across.
The diet of the masked stingaree consists primarily of polychaete worms 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, with a general shift from the latter to the former as the ray ages. It is aplacental viviparous, with females typically bearing one pup annually and nourishing it with histotroph ("uterine
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
milk"). The 10–12 month long gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
consists of a five month period of suspended development
Embryonic diapause
Delayed Implantation or Embryonic Diapause is a reproductive strategy used by approximately 100 different mammals in seven or eight different orders. In embryonic diapause, the embryo does not immediately implant in the uterus, but is maintained in a state of dormancy. Little to no development...
for the egg, followed by rapid growth of the 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...
and birthing in late April or early May. The International Union for Conservation of Nature (IUCN) has listed the masked stingaree under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
. Fishing pressure on this species is largely limited to a small number of scallop
Scallop
A scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are a cosmopolitan family, found in all of the world's oceans. Many scallops are highly prized as a food source...
and prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
trawlers. Most such incidental capture
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...
s result in the ray being released alive, though it does have a tendency to abort any unborn young during capture.
Taxonomy
Peter Last and Martin Gomon described the masked stingaree in a 1987 issue of Memoirs of the National Museum of Victoria, giving it the specific epithet personata (from the LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
personatus, meaning "masked") in reference to its distinctive coloration. A male 23 cm (9.1 in) across was designated as the type specimen; it was collected by the research trawler FRV Hai Kung from northeast of Cape Naturaliste
Cape Naturaliste
Cape Naturaliste is a headland in the south western region of Western Australia at the western edge of the Geographe Bay. It is the northernmost point of the Leeuwin-Naturaliste Ridge which was named after the cape...
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
on 23 April 1981.
Distribution and habitat
Found off Western Australia from Shark BayShark Bay
Shark Bay is a World Heritage listed bay in Western Australia. The term may also refer to:* the locality of Shark Bay, now known as Denham* Shark Bay Marine Park* Shark Bay , a shark exhibit at Sea World, Gold Coast, Australia* Shire of Shark Bay...
to Geographe Bay
Geographe Bay
Geographe Bay is located in the South West of Western Australia around 220 km southwest of Perth.The bay was named in May 1801 by French explorer Nicolas Baudin; Baudin named the bay after his ship, Géographe. The bay is a wide curve of coastline extending from Cape Naturaliste past the towns...
, the masked stingaree is one of the most abundant representatives of its family within its range, particularly in the south. This bottom-dwelling ray has been reported from the shore to a depth of 115 m (377.3 ft) on the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
, and seems to be most common in offshore waters 20–35 m (65.6–114.8 ft) deep. It favors sandy flats 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. There is no evidence of segregation by age or sex, or of seasonal migration
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
s.
Description
The pectoral fin disc of the masked stingaree is approximately as long as wide, and has a rounded shape. The anterior margins of the disc are nearly straight and converge at an obtuse angle on the fleshy, non-protruding snout. The eyes are modestly sized and immediately followed by comma-shaped spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s with angular posterior rims. The outer margin of each nostril is enlarged into a broad, flattened lobe. Between the nostrils is a skirt-shaped curtain of skin with a fringed trailing margin, that conceals the small mouth. The lower jaw bears a patch of subtle papillae (nipple-shaped structures); there are also 3–4 papillae on the floor of the month. The small teeth have roughly oval bases. The five pairs of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s are short.
The pelvic fins are small with rounded margins. The tail measures 67–86% as long as the disc; it has an oval cross-section and is slightly flattened at the base. There is a single serrated stinging spine on the upper surface of the tail, which is immediately preceded by a rather large 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...
. The tail ends in an elongated, leaf-shaped caudal fin, and lacks lateral fin folds. The skin is devoid of dermal denticles. The masked stingaree has an ochre to gray dorsal coloration with two large, distinctive dark blotches, one forming a "mask" around the eyes and the other at the center of the disc; these blotches may be connected by thin lines along the midline and on either side. The underside is white, becoming darker at the fin margins. The dorsal and caudal fins are black in young rays, and fade to gray in adults. Males and females grow up to 27 cm (10.6 in) and 31 cm (12.2 in) across respectively.
Biology and ecology
Polychaete worms and crustaceanCrustacean
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 are the predominant sources of food for the masked stingaree; on occasion sipunculid worm
Sipuncula
The Sipuncula or Sipunculida is a group containing 144-320 species of bilaterally symmetrical, unsegmented marine worms...
s, molluscs, and echinoderm
Echinoderm
Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....
s are also taken. This species preys on both sedentary polychaetes, which generally inhabit deeply buried tubes, and on errant polychaetes, which are generally more mobile and shallowly buried. The expanded lobes and sensory papillae adjacent to its mouth likely aid in locating and excavating such burrowing prey. Young rays feed mainly on crustaceans, including mysids
Mysidacea
Mysida is a group of small, shrimp-like crustaceans, an order in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch, or marsupium, in females. Mysids are mostly found in marine waters throughout the world, but are also important in...
, amphipods, cumacea
Cumacea
Cumacea is an order of small marine crustaceans, occasionally called hooded shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans.-Anatomy:...
ns, tanaids
Tanaidacea
The crustacean order Tanaidacea make up a minor group within the class Malacostraca. There are about 940 species in this order.-Description:...
, and shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
. With age polychaetes are added to the diet; sedentary polychaetes are significant to rays 13–29 cm (5.1–11.4 in) across, while errant polychaetes become progressively more important such as that the largest rays eat little else.
Like other stingrays, the masked stingaree is aplacental viviparous. Females have a single functional uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
(the left) and produce a single pup (rarely two) per year. Ovulation
Ovulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...
and mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
occur from mid-June to mid-July; fertilized eggs are enclosed by a delicate brown capsule and maintained in a state of diapause
Embryonic diapause
Delayed Implantation or Embryonic Diapause is a reproductive strategy used by approximately 100 different mammals in seven or eight different orders. In embryonic diapause, the embryo does not immediately implant in the uterus, but is maintained in a state of dormancy. Little to no development...
(dormancy
Dormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
) within the uterus until November. Afterward the 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 develop rapidly and are sustained by nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
-rich histotroph ("uterine milk") produced by the mother; an average embryo increases in disc width from 1.1 cm (0.433070866141732 in) in December to 11 cm (4.3 in) in April, to be born in late April or early May at a disc width of 13 cm (5.1 in). The total gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
, including diapause, lasts 10–12 months. Females grow more slowly and to a larger ultimate size than males. Males mature sexually
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at around 22 cm (8.7 in) across and females at 23 cm (9.1 in) across; both sexes mature on average at four years of age. The maximum lifespan is 10 years for males and 16 years for females.
Human interactions
The scallopScallop
A scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are a cosmopolitan family, found in all of the world's oceans. Many scallops are highly prized as a food source...
and prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
trawl fisheries operating off Perth
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
and Mandurah regularly take the masked stingaree 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...
, though only a small number of vessels are involved. This ray may also be caught incidentally by small-scale fisheries further north, though overall it does not face substantial fishing pressure. When caught, the masked stingaree usually survives to be discarded, though the tendency of captured stingarees to abort their young merits concern. Given the limited conservation threats faced by this common species, the International Union for Conservation of Nature (IUCN) has listed it under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
. This species would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.