Feeding on fishes, cephalopods, and crustaceans, the Japanese angelshark is a nocturnal ambush predator that spends most of the day lying still on the sea floor.

The Japanese angelshark was described by Dutch ichthyologist Pieter Bleeker in an 1858 volume of the scientific journal Acta Societatis Scientiarum Indo-Neerlandicae.

The eyes are oval and widely spaced; closely behind are crescent-shaped spiracles with large, boxy projections inside their anterior rims.

The dorsal surface is covered by medium-sized dermal denticles, and a distinctive row of large thorns is present along the midline of the back and tail.

[6] Some older sources reported it may occur in the Philippines, but recent research suggests the only angel shark species in that area is S.

[1][7] During the day, the Japanese angelshark mostly lies partly buried on the bottom; its complex color pattern provides camouflage as it ambushes nearby prey.

[9] Parasites documented from this species include the tapeworms Phyliobothrium marginatum and Tylocephalum squatinae,[10] the copepods Eudactylina squatini[11] and Trebius shiinoi,[12] and the praniza larvae of the isopod Gnathia trimaculata.

Across much of its range, it is a frequent catch (intentional or not) in bottom trawls and probably also set nets and demersal gillnets; the meat is eaten and the rough skin is made into a type of leather called shagreen for use in wood finishing.

Trawling activity in the Yellow Sea and other parts of the northwestern Pacific is intense and, coupled with pollution, has had a serious impact on the local ecosystem.

The Japanese angelshark population is suspected to have declined by up to 50% or more under these conditions, leading the species to be assessed as critically endangered by the International Union for Conservation of Nature (IUCN).