RESEARCH: The bulging eyes of a stingray make it swim fast

The more streamlined an animal, the faster it is. To be streamlined means that the shape of the animal has smooth, flowing lines that enable it to reduce resistance to movement (called drag), such as through water or air. 

Research scientists have found that the bulging eyes and mouth of a stingray makes it a faster swimmer. This seems impossible, because any part of a body that is protruding (sticking out) usually makes an animal slower.

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CREATURE FEATURE: Bluespotted Ribbontail Ray

The Bluespotted Ribbontail Ray (Taeniura lymma) is a marine (saltwater) stingray in the Dasyatidae family of stingrays. It is also known as the Bluespotted Fantail Ray, the Bluespotted Stingray, or the Lagoon Ray.

The Bluespotted Ribbontail Ray has an oval-shaped disc with electric blue spots on a greyish-yellow coloured skin. The spots vary in size. It has a pair of blue stripes on its tail. It has large, bright-yellow, protruding eyes, a rounded snout (nose), and a short, thick tail. It is mainly smooth, except for a few small thorns in the middle of its back. Its belly is white.

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Southern Stingray

The Southern Stingray (Hypanus americanus) is a marine (saltwater) whiptail stingray.

The Southern Stingray has a flat, diamond-shaped body with sharp, angular corners. It is muddy-brown, olive, or grey with a white underbelly. It has a barb at the end of its long, thin tail. The barb is serrated (saw-like) and is covered with poisonous mucous. Its wing-like fins propel it through the water. Its eyes are on top of its head. 

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What is the difference between the Oscellate River Stingray and the Thornback Ray?

What is the difference between the Oscellate River Stingray (Potamotrygon motoro) and the Thornback Ray (Raja clavata)?

The Oscellate River Stingray is a marine (saltwater) fish, whereas the Thornback Ray is a freshwater river fish. 

Both the Oscellate River Stingray and the Thornback Ray have two raised eyes, close together, on the top of their backs. 

The Oscellate River Stingray has a beige or brown body with numerous yellow-orange dark-ringed spots, whereas the Thornback Ray varies in colour from light-grey or light-brown with either dark or light blotches.  

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Ocellate River Stingray

The Oscellate River Stingray (Potamotrygon motoro) is a freshwater ray in the Potamotrygonidae family of stingrays. It is also known as the Peacock-Eye Stingray or the Black River Stingray.

The Oscellate River Stingray has a flat, round-shaped, beige or brown body with numerous yellow-orange spots that have dark rings around them. Its underbelly is smooth and white. Its eyes are located on its back and are raised. 

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Spotted Ray

The Spotted Ray (Raja montagui) is a marine (saltwater) ray in the Rajidae family of stingrays. It is also known as the Sweet Ray. It is related to the Skate. 

The Spotted Ray is a rhomboid shape – like a kite – with rounded wing-tips. It is brownish-grey with numerous small dark spots. Its upper surface is smooth when young and prickly when it matures. Its underbelly is smooth and white. It has two equal-sized dorsal fins at the end of its tail. 

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Thornback Ray

The Thornback Ray (Raja clavata) is a marine (saltwater) fish in the Rajidae family of rays. 

The Thornback Ray has a flat body in the shape of a kite or diamond. It has broad, winglike pectoral fins. It has a long thorny tail. Its back is covered with many thorny, prickly spikes. Some of the thorns look like thick buttons, called bucklers. Older females also have thorns on their underbelly. 

It varies in colour, from light-grey or light-brown to grey with dark blotches or brown with light beige blotches. Its underside is creamy-white. Its eyes are close together at the top of its head. 

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Common Stingray

The Common Stingray (Dasyatis pastinaca) is a marine (saltwater) cartilaginous fish (without bones, like a shark). Instead of a bony skeleton, it has cartilage, which is the same substance as the human nose and human ears.

The Common Stingray is thin, flat, and diamond-shaped, but slightly wider than long (like a kite). It is pale-grey, brown or olive-green, with smooth skin. Its small mouth is located on its underside and its bulging eyes are close together on the top of its head. It has small blunt teeth. It has a long, tapering, whip-like tail with two dorsal fins and a venomous barb. It has five pairs of small gills, which enable it to breath underwater.

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Cartilage

What is cartilage?

Cartilage is smooth elastic tissue, such as the human rib cage, ear, and nose.

Cartilage does not contain blood vessels or nerves.

Sharks, rays, and skates are cartilaginous fish because they have a skeleton made entirely of cartilage.

Southern Stingray

The Southern Stingray (Dasyatis americana) is a marine cartilaginous fish (fish without bones, like a shark). Instead of a bony skeleton, it has cartilage, which is the same substance as the human nose and human ears.

The Southern Stingray has a thin, flat body, like a diamond-shaped disc (or kite-shaped), that can be brown, olive-green-brown, or grey. It has a white underbelly, where its small mouth is located. It has a long, tapering tail with two dorsal fins and venomous serrated (saw-like) barbs. Its bulging eyes are on the top of its head, close together. It has five pairs of small gills which enable it to breath underwater.

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