A ---------- has about 400 to 700 vibrissae, or whiskers, in 13 to 15 rows on its snout. Vibrissae are attached to muscles and are supplied with blood and nerves. A ---------- moves its snout through bottom sediment to find food. Abrasion patterns created by their tusks show that they are dragged through the sediment, but are not used to dig up prey.?