[2] In life, the animals are red or pinkish, but with white tips to the chelae (claws) on the enlarged third pereiopods (walking legs).

[2] Most specimens of J. spinulatus have been collected from the Red Sea at depths of 434–778 metres (1,424–2,552 ft), where the water is warm.

[2] The earliest discovered specimens of J. spinulatus were assigned by Heinrich Balss to the species Stenopus spinosus.

This was based on a single damaged holotype male, collected in the Lobetoli Strait, east of Flores, Indonesia, and the placement in the genus Engystenopus was considered questionable.

[2] The most distinctive characteristics of Engystenopus are characters of the third pereiopod, which was lacking from all the early specimens.