| False catshark | |
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| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Order: | Carcharhiniformes |
| Family: | Pseudotriakidae |
| Genus: | Pseudotriakis Brito Capello, 1868 |
| Species: | P. microdon |
| Binomial name | |
| Pseudotriakis microdon Brito Capello, 1868 |
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| Range of the false catshark | |
| Synonyms | |
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Pseudotriakis acrales Jordan & Snyder, 1904 |
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The false catshark (Pseudotriakis microdon) is a species of ground shark in the family Pseudotriakidae, and the sole member of its genus. It has been reported from a number of locations worldwide, usually at depths of 200-1,500 meters (660-4,900 ft) on the continental slopes. A large, slow-moving shark, it feeds mostly on bony fishes but also takes elasmobranchs and cephalopods, and scavenges off the sea floor. It is one of the few non-lamnoid sharks known to exhibit intrauterine oophagy, in which the developing embryos feed on eggs ovulated by the mother. This species is of minimal interest to fisheries.
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The Pacific populations of the false catshark were formerly regarded as a separate species, Pseudotriakis acrales; Leonard Compagno synonymized the two species in 1984 based on a lack of distinguishing characteristics. The closest living relative of the false catshark is the slender smooth-hound (Gollum attenuatus), and some authors place that species in the Pseudotriakidae.[2]
The false catshark is known from scattered locations worldwide, including New York, New Jersey, Cuba, Brazil, Iceland, France, Portugal, Madeira, Canary Islands, the Azores, Senegal, Cape Verde, the Aldabra Islands, Japan, Taiwan, Australia, New Zealand, and Hawaii. It is found near the bottom on continental and insular slopes from 173 to 1,890 meters (570-6,100 ft), but occasionally wanders over the continental shelf into shallower water.[3]
The false catshark is a large, bulky, soft-bodied shark that grows up to 3 meters (10 ft) long. It has long, narrow cat-like eyes with rudimentary nictating membranes, long teardrop-shaped spiracles, and broadly angular anterior nasal flaps. The mouth is huge and wide, extending behind the eyes and containing 200 or more rows of small, cuspidate teeth. The first dorsal fin is very long, low, and keel-like, while the second dorsal fin is triangular. The origin of the first dorsal fin is above the free rear tips of the pectoral fins, and the rear base is above the origins of the pelvic fins. The lower lobe of the caudal fin is barely developed. The coloration is a uniform dark brown, with darker posterior edges on the dorsal, pelvic, anal, and caudal fins.[2][3]
The large body cavity, enormous oil-filled liver, and soft musculature, fins, and skin of the false catshark suggest that it has a sluggish lifestyle, able to hover off the sea bottom at near-neutral buoyancy. It feeds on a wide variety of deepsea fishes and cephalopods, including cutthroat eels, grenadiers, snake mackerel, and lanternsharks, and its large mouth allows it to ingest items of considerable size. The stomach contents of some Pacific specimens also contained surface-dwelling fishes such as frigate mackerel, needlefishes, and pufferfishes, which were likely scavenged by the shark after sinking to the bottom. Notably, the stomach of a specimen from the Canary Islands contained mostly garbage, including potatoes, a pear, a plastic bag, and a soft drink can.[2][4]
Reproduction is ovoviviparous, with females bearing litters of two (possibly four) pups measuring 120-150 cm (47-59 in) long. The gestation period is unknown, but is presumed to be over one year and possibly 2-3 years. The embryos exhibit a modified form of intrauterine oophagy in which they ingest yolk fragments, which are transferred to an external yolk sac and used in the last stages of gestation.[5] The females produce enormous numbers of eggs, some 20,000 per ovary for a 2.7 meter (9 ft) specimen. Males mature at about 2.4 meters (8 feet) long and females at 2.8 meters (9 ft).[2][4]
The false catshark is infrequently caught on deep-set longlines and more rarely in bottom trawls.[2] The fins, meat, and cartilage are utilized but are of limited value.[3] The World Conservation Union assessed this species as Data Deficient, noting that due to its low reproductive rate, its populations may be vulnerable to depletion via bycatch with the continued expansion of deep-sea fisheries.[1]
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