Sparsely-spotted stingaree facts for kids
Quick facts for kids Sparsely-spotted stingaree |
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| Conservation status | |
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Urolophidae
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Urolophus
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U. paucimaculatus
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| Urolophus paucimaculatus J. M. Dixon, 1969
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| Range of the sparsely-spotted stingaree | |
The sparsely-spotted stingaree (Urolophus paucimaculatus) is a type of stingray. It is also called the white-spotted stingaree or Dixon's stingaree. You can often find this ray off the southern coast of Australia.
This ray loves sandy areas and seagrass beds. It lives on the ocean floor, from close to shore down to at least 150 meters (490 feet) deep. In the northern parts of its home range, it tends to live in deeper water.
The sparsely-spotted stingaree can grow up to 57 centimeters (22 inches) long. It has a wide, diamond-shaped body. Its top side is usually plain gray with a V-shaped mark between its eyes. Rays from southern waters often have small, dark-edged white spots. This ray also has a special bell-shaped flap of skin between its nostrils. Its tail has skin folds on each side and a leaf-shaped tail fin, but no fin on its back.
During the day, this stingaree is not very active. It mostly eats small ocean creatures like crabs and shrimp. It also eats worms and other tiny animals that live on the seabed.
Female stingarees give birth to live young. They feed their babies with a special "uterine milk" inside their bodies. The way they reproduce is a bit different depending on where they live. Females in the east can have up to six babies after a twelve-month pregnancy. Females in the west usually have one or two babies after a ten-month pregnancy. Western rays also grow up slower and live longer than eastern rays.
This stingaree has a venomous (poisonous) sting that can hurt humans. It might sting if it feels bothered. The International Union for Conservation of Nature (IUCN) says this ray is of "Least Concern" for its survival. This is because not much fishing happens in most of the areas where it lives.
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About the Sparsely-Spotted Stingaree
The sparsely-spotted stingaree was first described in 1969 by Joan Dixon. She worked at the Museums Victoria. Its scientific name, paucimaculatus, comes from Latin words meaning "few" and "spotted." This name describes the spots on its body. The first ray studied was found near Cape Patton in Victoria.
Scientists have noticed that stingarees from the eastern and western parts of Australia are a bit different. They have different life cycles. The IUCN suggests that these differences might mean they are different types of stingarees. More study is needed to be sure.
Where They Live and Their Home
The sparsely-spotted stingaree is one of the most common cartilaginous fish (fish with cartilage instead of bones) in southern Australia. It lives from New South Wales all the way to Western Australia, including all of Tasmania. In recent years, it has moved further south. This might be because of climate change. In a place called Port Phillip, its numbers grew from 1970 to 1991. This probably happened because fishing reduced the number of other fish that competed for food with the stingaree.
This ray lives on the bottom of the ocean. It likes many different sandy or seagrass areas. You can find it in shallow, calm bays and inlets, or out on the open continental shelf in waters over 150 meters (490 feet) deep. Rays found further north, like in the Great Australian Bight, usually live deeper, often more than 80–100 meters (260–330 feet) down. But rays found further south, near Victoria and Tasmania, are most common in waters less than 30 meters (98 feet) deep. Scientists don't see them separating by age or sex. However, they might move further offshore during winter.
What the Stingaree Looks Like
The sparsely-spotted stingaree has a body that looks like a diamond. It is wider than it is long, with rounded corners. The front edges of its body are almost straight and meet at a wide angle at its snout. Its snout is fleshy and barely sticks out from its body. Its small eyes are right in front of comma-shaped holes called spiracles.
The outer edge of each nostril has a small bump. Between the nostrils, there is a bell-shaped flap of skin with a finely fringed edge. Only one other stingaree, the Kapala stingaree, has a similar nasal flap. The stingaree's small mouth has five or six small, nipple-like bumps on the bottom. Most of these bumps have split tips. There are also more small bumps on the outside of its lower jaw. Its teeth are small and oval-shaped, arranged in a pattern like the dots on a dice (a quincunx). It has five pairs of short gill slits. Its pelvic fins are small and round.
The tail of this stingaree is about 77–98% as long as its body. It is very flat at the base and gets thinner towards the tip. The tip has a deep, leaf-shaped caudal fin (tail fin). There is a clear fold of skin running along each side of the tail. A serrated (saw-like) stinging spine is located on the top of the tail, about halfway along its length. This ray does not have a dorsal fin (back fin).
Its skin is smooth and has no dermal denticles (tiny, tooth-like scales). The stingaree is light gray on top with a darker V-shaped mark between its eyes. It is white underneath, with slightly darker edges on its body. Most rays from the southern part of its range also have a few small, evenly spaced white spots with dark borders on their backs. Young stingarees have a black tail fin, which gets lighter as they get older. The biggest stingaree ever found was 57 centimeters (22 inches) long.
Life Cycle and Diet
During the day, the sparsely-spotted stingaree often rests still on the ocean floor. It sometimes buries itself in the sand. Its main food is crustaceans, which make up over 80% of what it eats. This includes small amphipods, mysids, and shrimp. Polychaete worms are another important food source, especially the ones that move around and are buried shallowly. Sometimes, it also eats molluscs, echinoderms (like starfish), and small bony fish.
As the stingaree grows older, it eats a wider variety of prey. For example, it eats fewer mysids, isopods, and amphipods. Instead, it eats more shrimp, polychaete worms, prawns, and crabs. The broadnose sevengill shark hunts and eats this stingaree. The stingaree can also be affected by parasites, including a type of tapeworm and other small worms.
Like other stingrays, the sparsely-spotted stingaree gives birth to live young. The mother provides food for her developing babies inside her body. This special food is called "uterine milk." Females have only one working ovary and uterus, on their right side. They reproduce once a year.
In the eastern group of stingarees, eggs are released in spring or early summer. A female can have one to six babies, and larger females have more babies. The pregnancy lasts about one year. Newborns are about 15–16 centimeters (5.9–6.3 inches) long. Males become ready to reproduce when they are about 28 centimeters (11 inches) long and two and a half years old. Females are ready when they are about 27 centimeters (11 inches) long and three years old. Males can live for at least 8 years, and females for 9 years.
In the western group, mating happens in early or mid-summer. Females usually have only one or two babies. The pregnancy lasts ten months, and babies are born in late spring or early summer. Newborns are about 13 centimeters (5.1 inches) across. Males are ready to reproduce when they are about 21 centimeters (8.3 inches) across and three years old. Females are ready when they are about 22 centimeters (8.7 inches) across and five years old. Western stingarees can live up to 14 years. In both groups, females grow slower but get bigger than males.
Interactions with People
The sparsely-spotted stingaree is said to be more aggressive than other stingarees. It will use its venomous sting if it feels threatened, and this can cause a painful injury to a person. People can eat this fish, but it is not often sold in markets.
Most of the areas where this ray lives, like the Great Australian Bight, don't have much fishing. However, many of these rays are accidentally caught by commercial fishing boats off southeastern and southwestern Australia. They are caught in nets like beach seines and bottom trawls. The sparsely-spotted stingaree often survives being caught, sorted, and thrown back into the ocean. However, this process can cause pregnant females to lose their unborn young. Even so, the number of rays lost to fishing seems to be okay for now. Because of this, the IUCN has listed this species as "Least Concern". There are some small Marine Protected Areas (MPAs) where it lives. It could also benefit from a plan made in 2004 called the Australian National Plan of Action for the Conservation and Management of Sharks.
