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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:

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Shark picture - green sawfish

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REEF MANTA RAY

Reef Manta Ray Manta alfredi

View all available Reef Manta Ray Pictures in the Shark Pictures Database

Common Names: Reef manta ray, Manta ray, Devil ray.

Scientific Name: Manta alfredi

Family: Mobulidae

Identification: Immense size (the largest of all the rays except for the closely related Manta birostris). Terminal mouth has well developed, flexible cephalic lobes. Single small dorsal fin set close to tail. No bump at base of dorsal. No caudal spine or cartilaginous mass at base of tail. Tail thin (filamental) approximately 123% of body length.

Black and black/white colour variations have been reported for this species. Body markings may be cryptic and often lead to confusion with M.birostris therefore the following characteristics should not be regarded as an identification tool:  Solid black or mostly black dorsum. Sometimes with symmetrical white patches forming a subtle V across the shoulders. Ventrum white with irregular dark spots and  blotches. Often with dark blotches between the gills. A thick, dusky band forming a chevron is often present along the posterior margin of the ventrum.

Size: Maximum wing span 5.5m but usually 3-4m. Disc width at birth 1.2m.

Habitat: Oceanic and inshore waters. Adults usually seen inshore. A regular visitor to seamounts where plankton is forced to the warmer surface layers.

Abundance and distribution: Tropical Indian Ocean and West Pacific. From the Red Sea to South Africa in the west to Japan, Southeast Asia and Western Australia and east to French Polynesia and Hawaii. Some reports from the Canary Islands and Cape Verde may be attributed to M.birostris.

Behavior: Manta rays are often seen where plankton is concentrated. They unroll their cephalic lobes and use them to channel plankton into their mouths. Occasionally they can be seen barrel-rolling in the water column when feeding. They may also breach; perhaps to rid themselves of parasites. Seen singly or in aggregations where food (plankton) is abundant. "Warm blooded" i.e. able to sustain higher temperatures within their bodies and brains relative to the ambient water temperature. This may be a tool for maintaining constant muscle function whilst moving in and out of thermoclines.

Reproduction: Ovoviviparous. Gives birth to one or two pups.

Conservation Status: Protected under CITES Appendix II. Considered 'Vulnerable' by the IUCN.  Quote: "The rate of population reduction appears to be high in several regions, up to as much as 80% over the last three generations (approximately 75 years), and globally a decline of 30% is strongly suspected. Currently this species has a high value in international trade (its gill rakers are used in Chinese medicines) and directed fisheries exist that target this species in what is certain to be unsustainable numbers. Artisanal fisheries also exist that target this species for food. Individuals are also taken as bycatch in everything from large-scale fisheries to shark control programs/bather protection nets. As a result of sustained pressure from fishing (both directed and bycatch) certain monitored subpopulations appear to have been depleted, such as in Indonesia. Of particular concern is the targeting of this species at critical habitats or well-known aggregation sites where, with relatively high catch-per-unit effort, numerous individuals can be targeted simultaneously or with relative ease.
Dive tourism involving this species is a growing industry and it has been demonstrated that sustainable tourism significantly enhances the economic value of such species in comparison to short-term returns from fishing. Tourism related industries can also negatively impact individual behaviour, entire populations and critical habitat for this species, thus the responsible development of these industries is recommended."

Citation: Marshall, A., Kashiwagi, T., Bennett, M.B., Deakos, M., Stevens, G., McGregor, F., Clark, T., Ishihara, H. & Sato, K. 2011. Manta alfredi. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>.

Photographs: Nuku Hiva, Marquisas Archipelago, French Polynesia.

Similar species: The reef manta is often confused with the larger oceanic manta Manta birostris. Althouh very similar, the oceanic manta has a distinct cartilaginous bulge at the base of its tail behind the dorsal fin and no spots on its ventral surface between its gills.

Reaction to divers: Sometimes curious but usually moves away when approached closely.

Diving logistics: There are many areas throughout the Indo Pacific where reef mantas can be encountered. Contact bigfishexpeditions.com for information about trips to Nuku Hiva where reef mantas are seen on most dives that are conducted.

 

 

 

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