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ANDY MURCH ELASMO GEEK

 

WHAT IS ELASMODIVER?

Not just a huge collection of Shark Pictures: Elasmodiver.com contains images of sharks, skates, rays, and a few chimaera's from around the world. Elasmodiver began as a simple web based shark field guide to help divers find the best places to encounter the different species of sharks and rays that live in shallow water but it has slowly evolved into a much larger project containing information on all aspects of shark diving and shark photography.

There are now more than 10,000 shark pictures  and sections on shark evolution, biology, and conservation. There is a large library of reviewed shark books, a constantly updated shark taxonomy page, a monster list of shark links, and deeper in the site there are numerous articles and stories about shark encounters. Elasmodiver is now so difficult to check for updates, that new information and pictures are listed on an Elasmodiver Updates Page that can be accessed here:

WHAT'S NEW?

Shark picture - green sawfish

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Vermiculate River Stingray - Potamotrygon castexi

 

All photographs copyright Andy Murch

Otorongo Ray / Jaguar Ray

 

Color morph somewhere between Otorongo and Estrella Ray (Star Ray)

 

Tigrinus Ray / Tigrillo Ray (this individual possibly a castexi / motoro hybrid)

View all available Potamotrygon castexi Pictures in the Shark Pictures Database

Common Names: Vermiculate River Stingray, Otorongo Ray, Jaguar Ray, Estrella Ray, Star Ray, Tigrinus Ray, Tigrillo Ray, Carpet Ray, Motelo Ray, and Tortoise Ray.

Latin Name: Potamotrygon castexi

Family: Potamotrygonidae

A note on the identification of South American Freshwater Stingrays. Dorsum patterns and colors are extremely variable among the freshwater rays of South America making positive identification using pattern and coloration alone extremely difficult. Some morphologically different species occasionally display an almost identical pattern and to make identification even harder there can be a degree of hybridization among sympatric species. Important characteristics to help the observer overcome these problems include the lateral markings on the tail, the presence or lack of raised denticles along the tail, the ratio of tail length to disc length, and the size and position of the eyes (although this last characteristic changes with age).

Identification: Tail powerfully built and noticeably longer than the body. Upper surface of tail either irregularly light spotted o a dark background or covered in dark lines on a lighter background. The lower half of the tail appears striped or barred when viewed laterally. The body disc has a fine light edge which is not always noticeable.

In the aquarium trade Vermiculate River Stingrays are broken down into at least 5 'variants' according to their patterning:

  • Otorongo Ray (Jaguar Ray): displays a dense covering of light spots sometimes forming an almost solid mass towards the centre of the disc. The outermost spots are more defined and more broadly spaced.

  • Tigrinus Ray (Tigrillo Ray): similar to above but the orange spots fuse to form a lattice of interconnecting broken shapes. Lighter outer spots more defined and separated.

  • Estrella Ray (Star Ray): less densely covered in spots resulting in a starry appearance. Central spots sometimes form clusters.

  • Motelo Ray (Tortoise Ray): similar to Otorongo pattern but the densely covered spots form distinct closely grouped clusters resulting in a honeycomb appearance or the plates on a tortoises back (but more numerous).

  • Carpet Ray: completely covered in light broken circles (formed from spots) and spots on a dark background.

Size: Maximum disc width 60cm

Habitat: River Basins in South America.

Abundance and distribution: Upper Amazon River basin (Guaporé, Beni, Solimões and Marañon rivers) and Paraná-Paraguay basin. Restricted to Argentina, Bolivia, Brasil, Paraguay, and Peru.

Behavior:

Reproduction: Matrotrophic viviparity.

Observations:

Similar species: Potamotrygon reticulata has very similar patterns but can be differentiated by the single horizontal line running laterally along the tail. In the southern part of its range P.castexi hybridizes with P.falkneri.

Reaction to divers: Unknown but some South American freshwater rays are known to act aggressively when threatened.

Diving logistics: There are currently no organized opportunities to interact with freshwater stingrays but aquarist collecting sites include Paraguay, Peru, and Brazil.

Other diving locations submitted by readers:

References and further reading:

Aqualog Freshwater Rays. Richard Ross & Frank Schafer

Sharks and Rays Elasmobranch guide to the World. Ralf M. Hennemann IKAN

Fishbase.com

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