The Pseudotriakidae are a small

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

ground shark Carcharhiniformes , the ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark. Members of this order are characterized by the presence ...

s, belonging to the order

Carcharhiniformes Carcharhiniformes , the ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark. Members of this order are characterized by the presenc ...

, containing the false catsharks (genera ''

Pseudotriakis The false catshark or sofa shark (''Pseudotriakis microdon'') is a species of ground shark in the family Pseudotriakidae, and the sole member of its genus. It has a worldwide distribution, and has most commonly been recorded close to the bottom ...

'' and ''

Planonasus ''Planonasus'' is a genus of ground sharks in the family Pseudotriakidae, native to the western Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. I ...

'') and gollumsharks (genus ''Gollum''). It contains the only ground shark species that exhibit intrauterine

oophagy Oophagy ( ) sometimes ovophagy, literally "egg eating", is the practice of embryos feeding on eggs produced by the ovary while still inside the mother's uterus. The word oophagy is formed from the classical Greek (, "egg") and classical Greek (, ...

, in which developing

fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal deve ...

es are nourished by eggs produced by their mother.

Undescribed species

One undescribed species is known - one in the genus ''Gollum'', (''Gollum'' sp. B) - the white-marked gollumshark.Weigmann, S., Stehmann, M.F.W. & Thiel, R. (2013): ''Planonasus parini'' n. g. and n. sp., a new genus and species of false cat sharks (Carchariniformes, Pseudotriakidae) from the deep northwestern Indian Ocean off Socotra Islands. ''Zootaxa, 3609 (2): 163–181.''

References

Shark families Taxa named by Theodore Gill {{Shark-stub