Lamna ditropis Shark Jaws
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Lamniformes
Family: Lamnidae
Genus: lamna
Species: ditropis
Common Name: Salmon Shark
Salmon Shark (Lamna ditropis)
The salmon shark, Lamna ditropis, was first described by Hubbs and Follett in 1947. The genus name Lamna is translated from Greek "lamna, -es" as a voracious fish. The species name ditropis is from the Greek "di" meaning two, and "tropis" meaning keel. Prior to 1947, salmon sharks were thought to be porbeagle sharks, Lamna nasus (then Lamna cornubica). Although these species are closely related, their ranges do not overlap. Salmon sharks are a Pacific species, and porbeagles are an Atlantic species.
The salmon shark gets its name from one of its prey items, the Pacific salmon (Oncorhyncus spp.). Although it is considered to be one of the main predators of Pacific salmon, the salmon shark is actually an opportunistic feeder with a wide-ranging diet.
As mentioned above, the salmon shark was called the porbeagle before it was recognized as a separate species. It belongs to the family Lamnidae, the mackerel sharks. In French, the salmon shark is known as requin-taupe saumon, in Spanish, marrajo salmón, and in German, Pazifischer Heringshai. The salmon shark is abundant in Japanese waters, and it has several local names in Japan, including the Japanese mackerel shark, nezumizame, mokazame, radukazame, and sakezame.
The salmon shark occurs only in the coastal and oceanic waters of the North Pacific. They can be found in the waters off Japan (including the Sea of Japan), off the western Pacific coasts of North Korea, South Korea, Russia (including the Sea of Okhotsk), and in the Bering Sea. The eastern portion of their range is bounded by the eastern Pacific coast of the Canada, the U.S., and possibly northern Mexico. Because the salmon shark only occurs in the Pacific, it can be easily distinguished from its relative the porbeagle, in the northern hemisphere, which only occurs in the Atlantic.
The salmon shark is a primarily pelagic species, but can be found in epipelagic, offshore, and coastal areas. It appears to prefer cold boreal to cool temperate waters, but has been caught in water temperatures from 36.5° to 75°F (2.5° to 24°C). The species can be found at the surface to depths below 500 ft (152 m), and has been photographed at 837 ft (255 m).
those of the pelagic fish that it principally preys on, as well as with reproductive seasons. The salmon shark gives birth in the spring and probably mates in the summer or autumn. Populations in the northwest Pacific breed in Japanese waters or in waters off the coast of Kamchatka and Sakhalin. In winter, when the water warms, they migrate north to more distant feeding grounds in the Sea of Okhotsk, the Bering Sea, and the Sea of Japan. In the spring, they return south to Japanese waters, areas of the open ocean, and the southern Kuril region, where the females give birth.
Populations of the northeast Pacific perform a similar north-south migration in the waters off California, Oregon, Washington, Alaska, and Canada. The females migrate south in the spring to give birth off Oregon and California, where a significant number of neonates and young juveniles are found beached at that time every year.
There appears to be a strong sexual segregation in this species with males dominating the western North Pacific and females dominating the eastern North Pacific. In fact, males and females probably do not form mixed groups, as catches of salmon sharks are almost always dominated by one sex or the other. Although trans-Pacific movements have not been documented, they are suspected to occur, particularly during the mating period, which is probably in summer or autumn.
Salmon shark populations also appear to be segregated by size, with large sharks generally inhabiting the more northern reaches of the species' range, and smaller sharks staying in the southern parts. The larger, more mature sharks are more active in migrations, like the ones described above, while juveniles tend to remain in nursery areas until they reach about 3.6 to 3.9 ft (110 to 120 cm) in length. The waters off the coast of California appear to be a major nursery ground for the northeast populations, with juveniles remaining there for one to two years after birth. The northwest salmon shark populations have nursery grounds in the open-water Pacific, Japanese waters, and the southern Kuril region.
The salmon shark has a heavy spindle-shaped body with a short blunt conical snout. The gill slits are large. The caudal peduncle is strongly keeled, with short secondary keels on the caudal base. The caudal fin is crescent-shaped. The large first dorsal fin has a free rear tip. The small second dorsal and anal fins can pivot.
The salmon shark is sometimes mistaken for the white shark (Carcharodon carcharias), but it can be distinguished by its shorter snout and the presence of secondary keels on the caudal base (the white shark has none).
The dorsal and lateral surfaces of the salmon shark are dark blue gray to black in color. Its dorsal fin is all dark, including the rear tip. The ventral surface of the snout anterior to the mouth is also dark, but the rest of the ventral surface of the body is white, often with dusky blotches (in adults only) and white patches over the pectoral bases. The dark blotches can also be used to distinguish the salmon shark from the white shark.
The salmon shark has moderately large blade-like teeth with lateral cusplets, small bumps or "mini-teeth" on either side of each tooth. The first upper lateral teeth have oblique (diagonally-oriented) cusps.
Harvested by a fishermen in Kesennuma Japan. Great for comparitive study for fossil hunters. This piece would be a nice addition to anyones collection or for Zoo's and aquariums educational department
| Size | Item # | Price | ||
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11.5" X 7" | SALMON1 | $350.00 | SOLD |
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11" X 8.5 " | SALMON2 | $350.00 | SOLD |