Pseudocarchariidae
1 species
The crocodile shark (Pseudocarcharias kamoharai) is a species of mackerel shark and the only extant member of the family Pseudocarchariidae.A specialized inhabitant of the mesopelagic zone, the crocodile shark can be found worldwide in tropical waters from the surface to a depth of 590 m (1,940 ft). It performs a diel vertical migration, staying below a depth of 200 m (660 ft) during the day and ascending into shallower water at night to feed. Typically measuring only 1 m (3.3 ft) in length, the crocodile shark is the smallest living mackerel shark. It can be distinguished by its elongated cigar-shaped body, extremely large eyes, and relatively small fins.
An active-swimming predator of pelagic bony fishes, squid and shrimp, the crocodile shark has a sizable oily liver that allows it to maintain its position in the water column with minimal effort. The size and structure of its eyes suggests that it is adapted for hunting at night. The crocodile shark is aplacental viviparous, with females typically giving birth to litters of four. The fetuses are oophagous, meaning that they feed on undeveloped eggs ovulated for this purpose by their mother. Due to its small size, the crocodile shark poses little danger to humans and is of little commercial importance. This species was responsible for damaging deep sea fiberoptic cables when the technology was first deployed in 1985.
The crocodile shark is almost circumtropical in distribution. In the Atlantic Ocean, it is known from off Brazil, Cape Verde, Guinea-Bissau, Guinea, Angola, South Africa, and Saint Helena Island, though it has not yet been reported from the northwestern Atlantic. In the Indian Ocean, it occurs in the Mozambique Channel and possibly the Agulhas Current and the Bay of Bengal. In the Pacific, it occurs from Japan, Taiwan, and the Korean Peninsula in the northwest, southward to Indonesia, Australia, and New Zealand, and eastward to the western coast of the Americas from Baja California to Chile, including the Marshall, Phoenix, Palmyra, Johnston, Marquesas, Line, and Hawaiian Islands in between. In New Zealand this species has been recorded at the Three Kings Ridge, off the coast of Northland and on the northern Kermadec Ridge.
From distribution records, the crocodile shark's range seems to be bound by the latitudes 37°N and 44°S, where the average sea surface temperature is 20 °C (68 °F). This species is not evenly distributed but is rather locally abundant in certain areas, suggesting that it is not strongly migratory. The crocodile shark is usually found in the pelagic zone from the surface to a depth of 590 m (1,940 ft). It is occasionally encountered inshore near the bottom and has been known to strand on the beaches of South Africa, possibly after being stunned by upwellings of cold water. In March 2017, one crocodile shark washed ashore dead off the coast of Devon, England in Hope Cove, the first ever seen off the coasts of the United Kingdom. Thus far, it remains unknown as to why this particular shark was present so far north of its normal range.
The crocodile shark (Pseudocarcharias kamoharai) is a species of mackerel shark and the only extant member of the family Pseudocarchariidae.A specialized inhabitant of the mesopelagic zone, the crocodile shark can be found worldwide in tropical waters from the surface to a depth of 590 m (1,940 ft). It performs a diel vertical migration, staying below a depth of 200 m (660 ft) during the day and ascending into shallower water at night to feed. Typically measuring only 1 m (3.3 ft) in length, the crocodile shark is the smallest living mackerel shark. It can be distinguished by its elongated cigar-shaped body, extremely large eyes, and relatively small fins.
An active-swimming predator of pelagic bony fishes, squid and shrimp, the crocodile shark has a sizable oily liver that allows it to maintain its position in the water column with minimal effort. The size and structure of its eyes suggests that it is adapted for hunting at night. The crocodile shark is aplacental viviparous, with females typically giving birth to litters of four. The fetuses are oophagous, meaning that they feed on undeveloped eggs ovulated for this purpose by their mother. Due to its small size, the crocodile shark poses little danger to humans and is of little commercial importance. This species was responsible for damaging deep sea fiberoptic cables when the technology was first deployed in 1985.
The crocodile shark is almost circumtropical in distribution. In the Atlantic Ocean, it is known from off Brazil, Cape Verde, Guinea-Bissau, Guinea, Angola, South Africa, and Saint Helena Island, though it has not yet been reported from the northwestern Atlantic. In the Indian Ocean, it occurs in the Mozambique Channel and possibly the Agulhas Current and the Bay of Bengal. In the Pacific, it occurs from Japan, Taiwan, and the Korean Peninsula in the northwest, southward to Indonesia, Australia, and New Zealand, and eastward to the western coast of the Americas from Baja California to Chile, including the Marshall, Phoenix, Palmyra, Johnston, Marquesas, Line, and Hawaiian Islands in between. In New Zealand this species has been recorded at the Three Kings Ridge, off the coast of Northland and on the northern Kermadec Ridge.
From distribution records, the crocodile shark's range seems to be bound by the latitudes 37°N and 44°S, where the average sea surface temperature is 20 °C (68 °F). This species is not evenly distributed but is rather locally abundant in certain areas, suggesting that it is not strongly migratory. The crocodile shark is usually found in the pelagic zone from the surface to a depth of 590 m (1,940 ft). It is occasionally encountered inshore near the bottom and has been known to strand on the beaches of South Africa, possibly after being stunned by upwellings of cold water. In March 2017, one crocodile shark washed ashore dead off the coast of Devon, England in Hope Cove, the first ever seen off the coasts of the United Kingdom. Thus far, it remains unknown as to why this particular shark was present so far north of its normal range.
