Found at depths of 400 to 800 m (1,300 to 2,600 ft) in the Pacific Ocean, they have been known to grow to 24 cm (9.4 in).

O. deletron has been found to break off its arms as a defense strategy.

Males find it difficult to detect the sex of other individuals they encounter in the dark depths, so they have adopted a strategy of attaching sperm packets to all individuals they meet.

[4] O. deletron are the most common species found in the stomachs of northern elephant seals sampled off the coast of California.

[6] It is also eaten by the enigmatic Perrin's beaked whale (Mesoplodon perrini).