Eastern shovelnose stingaree facts for kids
Quick facts for kids Eastern shovelnose stingaree |
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| Conservation status | |
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Urolophidae
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| Genus: |
Trygonoptera
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T. imitata
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| Trygonoptera imitata Yearsley, Last & M. F. Gomon, 2008
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The eastern shovelnose stingaree (Trygonoptera imitata) is a type of stingray. It lives only in the coastal waters off southeastern Australia. You won't find it in Tasmania. This stingaree has a round, flat body called a pectoral fin disc. This disc is wider than it is long. It also has a soft snout (nose) that looks a bit like a shovel. Its tail is fairly short and ends in a caudal fin (tail fin).
The stingaree's nostrils have special flaps on their outer edges. There's also a curtain of skin between the nostrils that looks like a skirt. This skin has a fringed, or frilly, edge. The top of the stingaree is usually plain brownish. Sometimes, it has a few darker or lighter spots. This is one of the bigger stingarees. It can grow to be at least 80 cm (31 in) (about 31 inches) long.
Eastern shovelnose stingarees mostly eat polychaete worms. They are quite common in very shallow, coastal bays. They prefer areas with soft sand or mud at the bottom. However, they can also live in deeper water, up to 120 m (390 ft) (about 390 feet) or more.
These stingarees give birth to live young. This is called aplacental viviparous reproduction. The mother provides her babies with a special nutrient-rich fluid, sometimes called "uterine milk." The babies develop inside the mother for 4 to 7 months. Before this, the eggs can stay in a resting state for a long time. Females usually have one litter of up to seven pups each year, from late February to April.
Sometimes, these stingarees are accidentally caught by fishing boats. This is known as bycatch. They can be caught in seine nets and bottom trawls. Their homes can also be harmed by coastal development and invasive species. The number of these stingarees has gone down in Port Phillip. However, the International Union for the Conservation of Nature (IUCN) currently lists them as a species of Least Concern. This means they are not in immediate danger of extinction.
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Discovering the Eastern Shovelnose Stingaree
Before 2008, scientists knew about this stingaree but hadn't officially named it. It was called Trygonoptera "sp. B." People often confused it with two other similar stingaree species. These were the common stingaree (T. testacea) and the western shovelnose stingaree (T. mucosa).
Because it looked so much like these other species, scientists Gordon Yearsley, Peter Last, and Martin Gomon gave it the name imitata. This name means "imitating" or "mimicking." The first official specimen studied was a 61 cm (24 in) long adult male. It was found in the Bass Strait, near Wilsons Promontory, Victoria.
Where They Live and Their Home
The eastern shovelnose stingaree lives off southeastern Australia. You can find it from Jervis Bay in New South Wales down to Beachport and possibly Gulf St Vincent in South Australia. They are also found in the northern Bass Strait and near Flinders Island. However, they don't seem to live in Tasmania itself.
Many of these rays live off the coast of Victoria. They are very common in Port Phillip and Western Port. This species lives on the bottom of the ocean, so it's called a bottom-dwelling species. They like calm, shallow areas near the coast. These places usually have soft sand or mud at the bottom, in water less than 5 m (16 ft) (about 16 feet) deep. But they have been found as deep as 120 m (390 ft) (about 390 feet). There's even a record of one found much deeper, at 200–440 m (660–1,440 ft) (about 650-1440 feet), on the continental slope.
What the Eastern Shovelnose Stingaree Looks Like
The body of the eastern shovelnose stingaree is rounded and flat. It's wider than it is long. The front edges of its body are mostly straight and meet at a blunt angle at its fleshy snout. The outer corners of its body are rounded. Its eyes are medium-sized. Behind the eyes are larger, comma-shaped holes called spiracles. These spiracles help the stingaree breathe.
Each nostril has a noticeable, flat flap on its outer edge. Between the nostrils, there's a curtain of skin that looks like a skirt. This curtain has a deep groove in the middle with small bumps (called papillae). Its back edge is deeply fringed. The small mouth is hidden by the lower jaw. The lower jaw has many small bumps. The floor of the mouth has three bumps in the middle and one or two near each corner.
Their teeth are blunt and oval-shaped. The teeth towards the inside of the lower jaw are more triangular with jagged edges. They are arranged in a pattern. The stingaree has five pairs of S-shaped gill slits.
Its pelvic fins are medium-sized and somewhat triangular. Male stingarees have strong, tapering claspers, which are used for reproduction. The tail is smooth and tapers to a point. It ends in a spear-shaped caudal fin (tail fin). The tail is about three-quarters as long as the body. Usually, there are two jagged stinging spines on top of the tail, about halfway along its length. The upper spine is usually bigger. The tail does not have any dorsal fins or fin folds. The skin of the stingaree is completely smooth.
The color on top of the stingaree ranges from yellowish to dark grayish brown. It's darkest along the middle of its back and lighter towards the edges of its fins. Some larger stingarees also have small black and beige spots. The underside of the stingaree is light-colored. It has dark fin edges and sometimes dark blotches on its belly. The tail is completely dark past its base. This species can reach a maximum length of 80 cm (31 in). This makes it the largest stingaree in its group and one of the largest in its family.
Life and Habits of the Stingaree
The eastern shovelnose stingaree eats small creatures that live on the ocean floor. These are called benthic organisms. They mainly eat polychaete worms. They dig pits in the sand or mud to find their food.
Female stingarees have only one working ovary, on their right side. Like other stingrays, they give birth to live young. This is called aplacental viviparous reproduction. After the eggs are fertilized, they stay in the uterus for 5 to 8 months without developing. Then, the babies (embryos) start to grow quickly for 4 to 7 months. At first, the babies get food from a yolk sac. Once the yolk is used up, the mother provides them with a special, nutrient-rich fluid called "uterine milk."
Females have one litter of babies each year, between late February and April. They lay new eggs right after giving birth. A female can have up to seven babies in one litter. Larger females tend to have more babies. Newborn stingarees are 20–25 cm (7.9–9.8 in) (about 8-10 inches) long. They weigh about 150 g (5.3 oz) (about 5 ounces).
Males become ready to have babies when they are about 46 cm (18 in) (18 inches) long and 4.5 years old. Females are ready when they are about 49 cm (19 in) (19 inches) long and 5 years old. These stingarees can live for at least 10 years for males and 12 years for females.
Stingarees and People
The eastern shovelnose stingaree is not aggressive towards humans. You can easily get close to them underwater. Their meat can be eaten, but it can be a bit tough if not cooked properly.
These stingarees are sometimes caught by accident by coastal fishing boats. This is called bycatch. They are caught in nets like beach and Danish seines and bottom trawls. This happens especially in the Southern and Eastern Scalefish and Shark Fishery (SESSF). Since they are caught in shallow water, they often survive when they are thrown back into the ocean. However, there's a concern about injuries from heavy fishing gear. Also, stingarees sometimes give birth early when they are caught.
Other things that might threaten this species include harm to their homes from coastal development and human activities. invasive species can also be a problem. The number of eastern shovelnose stingarees in Port Phillip has gone down in the last ten years. This, along with ongoing fishing, led the International Union for the Conservation of Nature (IUCN) to list them as Near Threatened. This means they might become endangered in the future.
However, their range includes some safe areas, like the Bass Strait, where there isn't much trawling. There are also several Marine Protected Areas (MPAs) recently created off Victoria. These areas help protect marine life. The stingaree could also benefit from Australia's 2004 National Plan of Action for the Conservation and Management of Sharks.
