Benthic just refers to the marine life on the bottom as opposed to at the surface or in the water column. It's not a pretentious or snooty term. It's definitely not a "howler." My friend Richard, who passed away last year, was a marine biologist...
Certainly startling, like walking up a covey of quail unexpectedly. As everyone's mother might say, "They could have poked your eye out." Other than that, the impact damage from a 100-gram feather-covered object shouldn't be bad.