Like other beaked whales, these whales are found mostly offshore in deep waters, but they may sometimes occur reasonably close to shore (MacLeod and Zuur 2005). A detailed analysis of habitat preferences in the Bahamas, where this species is commonly encountered, indicated that Blainville’s beaked whales were found preferentially in waters of intermediate depth gradients and depths between 200 and 1,000 m (continental slope waters). These may be areas of increased prey availability caused by interactions of currents and local topography (MacLeod and Zuur 2005). Observations around Hawaii seem to indicate that animals prefer water depths of 700-1,000 m (Baird et al. 2006). Ritter and Brederlau (1999) sighted Mesoplodon densirostris 24 times between September 1995 and August 1997 off La Gomera, Canary Islands. Of the seven sightings for which such information was recorded, mean depth was 320 m (SD = 270 m), and mean distance from shore was 4.39 km (SD = 1.85 km).

Squid are apparently the main food items, but some deepwater fish may be taken as well. Like most other ziphiids, they are thought to be suction feeders (Heyning and Mead 1996).