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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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BLOTCHY SWELL SHARK

Blotchy Swell Shark

 

 

View more Blotchy Swell Shark Pictures

 

Common Names: Blotchy Swell Shark, Japanese Swell Shark, Swellshark, Balloon Shark.

 

Latin Name: Cephaloscyllium umbratile.

 

Family: Scyliorhinidae.

 

Identification: Body blotched with shades of grey and brown. Darker blotches form 7 poorly defined saddles on body and tail. ventrum lighter and mostly unspotted. First dorsal origin posterior to pelvic fin origin. Second dorsal fin much smaller than first with origin slightly posterior to origin of anal fin. Eye large and golden. Spiracle small. Body shape may appear much wider due to ingestion of water when threatened.

 

Size: Max 140cm.

 

Habitat:  Found on rocky reefs of the continental slope from 18-220m. Mostly between 90-200m.

 

Abundance and Distribution: Northwest Pacific Ocean from Honshu, Japan south to Korea, Mainland China and Taiwan. Records of blotchy swell sharks from Papua New Guinea and New Zealand probably refer to Steven's swell shark C.stevensi and the draftboard shark C.isabellum respectively. Abundant where is occurs.

 

Behavior:  Unknown.

 

Diet: Varied. Small fishes, crustaceans and cephalopods. Known to prey on at least 10 other cartilaginous species including the lantern sharks and the cloudy catshark and its eggs.

 

Conservation Status: Listed as Data Deficient by the IUCN. Little is known of the biology but this is a relatively small oviparous species and may therefore be more productive than larger live-bearing sharks. Although no data are available to assess population trends, the species is apparently still abundant in areas that are heavily fished by trawlers. Small scyliorhinid species have proven resilient to population decline, even where they are heavily fished (for example the Smallspotted Catshark (Scyliorhinus canicula) in the northeast Atlantic). However, records of Japanese Swellshark apparently include C. umbratile and a smaller undescribed sympatric species. The two species may be confused and C. umbratile is a larger catshark, and may be more vulnerable to depletion. Therefore this species is assessed as Data Deficient until further information is available on its life-history, catches in fisheries and population trends.

However, the blotchy swell shark is a retained bycatch of commercial bottom trawl and longline fisheries off Japan (Taniuchi 1988). It is captured incidentally by shrimp bottom trawlers using nets with mesh ~2-4 cm in diameter, so both adults and juveniles are retained by the trawl (S. IglÚsias pers. obs. 2007). The species is sometimes observed on the Tachi and Nan Fang Hao fish markets, Taiwan. It is apparently still abundant in areas that are heavily fished by trawlers

 

Reproduction: Oviparous. The Japanese swell shark lays two flattened egg cases throughout the year with no apparent seasonal preference. Captive female sharks held without a mate have continued to deposit egg capsules for multiple years implying that this species is able to store sperm.

 

Photographs: Tateyama, Honshu, Japan.

 

Similar species: The Blotchy Swell Shark shares much of its range with a smaller undescribed species of swell shark (Compagno et al. 2005).

 

Reaction to divers: Remains motionless. When harassed by divers the Japanese swell shark may attempt to inflate but more commonly relocates.

 

Diving logistics: The blotchy swell shark generally inhabits sites too deep for observation by divers. It is occasionally seen within recreational limits by divers in Chiba and on the Izu Peninsula on the south side of Honshu Island, Japan.

 

Citations: IglÚsias, S., Tanaka, S. & Nakaya, K. 2009. Cephaloscyllium umbratile. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>.

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