Lobed stingaree
Encyclopedia
The lobed stingaree is a common species
of stingray
in the family
Urolophidae, endemic to southern Western Australia
in shallow, inshore sand and seagrass
habitat
s. This species is plain sandy in color above and has a broad, rounded pectoral fin disc. It is characterized by an enlarged, semicircular skin lobe of unknown function on the inner rim of each nostril. Its tail is slender, with lateral skin folds and a lance-like caudal fin but no dorsal fin
. The maximum recorded width is 27 cm (10.6 in).
A benthic predator, the lobed stingaree feeds mostly on crustacean
s, and to a much lesser extent on small bony fishes, polychaete worms, and molluscs. It is aplacental viviparous, with females typically bearing a single pup every October or November after a gestation period
of ten months. Developing embryo
s are nourished by maternally produced histotroph ("uterine milk") after they exhaust their supply of yolk. In the northern portion of its range, the lobed stingaree is frequently caught incidentally
by trawlers. Though it generally survives the experience, it has a tendency to abort its young when captures. However, this species is not greatly affected by human activity overall, and it has been listed under Least Concern
by the International Union for Conservation of Nature (IUCN).
described the lobed stingaree in an 1966 issue of the Journal of the Royal Society of Western Australia, giving it the specific epithet lobatus in reference to its unique nasal lobes. The type specimen was collected from a depth of 31–33 m (101.7–108.3 ft) northeast of Rottnest Island
off Western Australia.
to Rottnest Island
. This bottom-dwelling species favors sandy flats and seagrass
beds, from the intertidal zone
to a depth of 30 m (98.4 ft). In the southern portion of its range, it tends to be found relatively far from shore. Individuals of different ages and sexes are not segregated from each other.
s, which have a rounded posterior margin. The outer posterior corner of each nostril forms a visible lobe. Between the nostrils is a skirt-shaped curtain of skin with a fringed trailing margin; the front corners of the curtain are enlarged into distinctive, semicircular lobes. The mouth is small and contains 9–10 papillae (nipple-like structures) on the floor; a handful of papillae are also found on the lower jaw. The small teeth have roughly oval bases. The five pairs of gill slit
s are short. The pelvic fins are small and rounded.
The tail is slender and very flattened, measuring 87–100% as long as the disc and bearing a prominent horizontal skin fold on either side. There is a dorsally positioned, serrated stinging spine near the caudal fin, which is long, narrow, and leaf-shaped. There is no dorsal fin
. The skin entirely lacks dermal denticles. This species is yellowish brown above, becoming slightly lighter at the lateral margins of the side, and white below; some individuals have irregular blotches and/or a dark stripe along the dorsal midline of the tail. The caudal fin becomes dark towards the tip.. Males and females can grow up to 24 cm (9.4 in) and 27 cm (10.6 in) across respectively.
s, in particular mysids, amphipods, shrimp
s, and cumacea
ns, which are captured on or just above the bottom. This species also feeds on polychaete
worms, small bony fishes, and rarely molluscs. Rays smaller than 19 cm (7.5 in) across take relatively more mysids, amphipods, and cumaceans, while larger rays take more shrimps and fishes, and have a more diverse diet overall. Its dietary composition also shifts seasonally, mostly reflecting the greater availability of shrimp in summer and fall and cumaceans in winter and spring. A known parasite of this species is a tapeworm in the genus Acanthobothrium. The function of its unique nasal lobes is unknown.
Like other stingrays, the lobed stingaree is aplacental viviparous. Females have a single functional uterus
, on the left, and an annual reproductive cycle. Mating
occurs in November and October and ovulation
from mid-November and mid-January, implying that the females store sperm
internally for 1–3 months before fertilization. The gestation period
lasts ten months; although up to six eggs may be fertilized, usually only a single pup (rarely two) develops to term. The embryo is initially nourished by an external yolk sac
; by five months of age, the embryo measures 5.4 cm (2.1 in) across and has transferred most of the remaining yolk into its digestive tract. By six months of age, the mother begins to deliver nutrient-rich histotroph ("uterine milk") through thread-like extensions of the uterine epithelium
called "trophonemata", which grow into the mouth, gills, and spiracles of the embryo. The disc and tail of the embryo are folded to hug the sting next to the body. Birthing occurs in late October or early November, with the newborns measuring around 11 cm (4.3 in) across. Females grow more slowly and to a larger ultimate size than males. Sexual maturity
is reached by males at around 16 cm (6.3 in) across and two years of age, and by females at around 20 cm (7.9 in) across and three years of age. The maximum lifespan is 12 and 14 years for males and females respectively.
by scallop
and prawn trawlers operating off Perth
and Mandurah in the northern part of its range. It usually survives to be released alive, though stingarees have a tendency to abort their young upon capture. As the number of vessels that catch this species is small, and it faces no other significant conservation threats within its range, the International Union for Conservation of Nature (IUCN) has assessed the lobed stingaree as of Least Concern
. It 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 southern 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...
in shallow, inshore sand 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:...
habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s. This species is plain sandy in color above and has a broad, rounded pectoral fin disc. It is characterized by an enlarged, semicircular skin lobe of unknown function on the inner rim of each nostril. Its tail is slender, with lateral skin folds and a lance-like caudal fin but no 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 maximum recorded width is 27 cm (10.6 in).
A benthic predator, the lobed stingaree feeds mostly on 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, and to a much lesser extent on small bony fishes, polychaete worms, and molluscs. It is aplacental viviparous, with females typically bearing a single pup every October or November after a 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:...
of ten months. Developing 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 are nourished by maternally produced histotroph ("uterine milk") after they exhaust their supply of yolk. In the northern portion of its range, the lobed stingaree is frequently caught incidentally
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 trawlers. Though it generally survives the experience, it has a tendency to abort its young when captures. However, this species is not greatly affected by human activity overall, and it has been listed 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...
by the International Union for Conservation of Nature (IUCN).
Taxonomy
Australian ichthyologist Roland McKayR. J. McKay
R. J. McKay is an Australia-born biologist known for his work in exotic and translocated freshwater fish in Australia. McKay is curator of fishes at the Queensland Museum and his work has been quoted extensively...
described the lobed stingaree in an 1966 issue of the Journal of the Royal Society of Western Australia, giving it the specific epithet lobatus in reference to its unique nasal lobes. The type specimen was collected from a depth of 31–33 m (101.7–108.3 ft) northeast of Rottnest Island
Rottnest Island
Rottnest Island is located off the coast of Western Australia, near Fremantle. It is called Wadjemup by the Noongar people, meaning "place across the water". The island is long, and at its widest point with a total land area of . It is classified as an A Class Reserve and is managed by the...
off Western Australia.
Distribution and habitat
Among the most abundant representatives of its family within its range, the lobed stingaree is found along a short stretch of the southwest Australian coast from EsperanceEsperance, Western Australia
Esperance is a large town in the Goldfields-Esperance region of Western Australia, located on the Southern Ocean coastline approximately east-southeast of the state capital, Perth. The shire of Esperance is home to 9,536 people as of the 2006 census, its major industries are tourism, agriculture,...
to Rottnest Island
Rottnest Island
Rottnest Island is located off the coast of Western Australia, near Fremantle. It is called Wadjemup by the Noongar people, meaning "place across the water". The island is long, and at its widest point with a total land area of . It is classified as an A Class Reserve and is managed by the...
. This bottom-dwelling species 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, from the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
to a depth of 30 m (98.4 ft). In the southern portion of its range, it tends to be found relatively far from shore. Individuals of different ages and sexes are not segregated from each other.
Description
The lobed stingaree has a rounded pectoral fin disc much wider than long, with nearly straight leading margins. The snout is fleshy and forms an obtuse angle; the tip may protrude slightly past the disc. The medium-sized eyes are followed by teardrop-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, which have a rounded posterior margin. The outer posterior corner of each nostril forms a visible lobe. Between the nostrils is a skirt-shaped curtain of skin with a fringed trailing margin; the front corners of the curtain are enlarged into distinctive, semicircular lobes. The mouth is small and contains 9–10 papillae (nipple-like structures) on the floor; a handful of papillae are also found on the lower jaw. 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 and rounded.
The tail is slender and very flattened, measuring 87–100% as long as the disc and bearing a prominent horizontal skin fold on either side. There is a dorsally positioned, serrated stinging spine near the caudal fin, which is long, narrow, and leaf-shaped. There is no 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 skin entirely lacks dermal denticles. This species is yellowish brown above, becoming slightly lighter at the lateral margins of the side, and white below; some individuals have irregular blotches and/or a dark stripe along the dorsal midline of the tail. The caudal fin becomes dark towards the tip.. Males and females can grow up to 24 cm (9.4 in) and 27 cm (10.6 in) across respectively.
Biology and ecology
Almost 90% of the food volume consumed by the lobed stingaree consists of 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, in particular mysids, amphipods, 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...
s, and 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, which are captured on or just above the bottom. This species also feeds on polychaete
Polychaete
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...
worms, small bony fishes, and rarely molluscs. Rays smaller than 19 cm (7.5 in) across take relatively more mysids, amphipods, and cumaceans, while larger rays take more shrimps and fishes, and have a more diverse diet overall. Its dietary composition also shifts seasonally, mostly reflecting the greater availability of shrimp in summer and fall and cumaceans in winter and spring. A known parasite of this species is a tapeworm in the genus Acanthobothrium. The function of its unique nasal lobes is unknown.
Like other stingrays, the lobed 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...
, on the left, and an annual reproductive cycle. 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...
occurs in November and October and 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...
from mid-November and mid-January, implying that the females store sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
internally for 1–3 months before fertilization. The 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:...
lasts ten months; although up to six eggs may be fertilized, usually only a single pup (rarely two) develops to term. The embryo is initially nourished by an external yolk sac
Yolk sac
The yolk sac is a membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals...
; by five months of age, the embryo measures 5.4 cm (2.1 in) across and has transferred most of the remaining yolk into its digestive tract. By six months of age, the mother begins to deliver nutrient-rich histotroph ("uterine milk") through thread-like extensions of the uterine epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
called "trophonemata", which grow into the mouth, gills, and spiracles of the embryo. The disc and tail of the embryo are folded to hug the sting next to the body. Birthing occurs in late October or early November, with the newborns measuring around 11 cm (4.3 in) across. Females grow more slowly and to a larger ultimate size than males. Sexual maturity
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...
is reached by males at around 16 cm (6.3 in) across and two years of age, and by females at around 20 cm (7.9 in) across and three years of age. The maximum lifespan is 12 and 14 years for males and females respectively.
Human interactions
The lobed stingaree is often caught incidentallyBycatch
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 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 trawlers 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 in the northern part of its range. It usually survives to be released alive, though stingarees have a tendency to abort their young upon capture. As the number of vessels that catch this species is small, and it faces no other significant conservation threats within its range, the International Union for Conservation of Nature (IUCN) has assessed the lobed stingaree as of 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...
. It would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.