It is a deepwater species, seldom being found at depths less than 500 m (1,600 ft), and occurs on either side of the Atlantic Ocean on the continental slope.

P. placenta is found in the Atlantic Ocean from Iceland and Greenland south to the Caribbean Sea in the west and the Gulf of Guinea in the east.

The three recognised subspecies are: P. p. placenta, which occurs in the northerly part of the range, P. p. sigsbei in the Caribbean, and P. p. africana off the coast of Africa.

They are fertilised by sperm released by males and rise at the rate of 25 cm (9.8 in) per minute, taking two days to ascend from bathyal depths to the surface.

The aggregation of many individuals in one area increases the chances of fertilisation taking place and the buoyancy of the eggs should aid in their dispersal.