Largest nostrils (proportionately)

The largest nostrils of any animal, in relation to its body size belongs to the male Linophryne arborifera, a species of deep-sea fish, whose nostril diameter is 37.7% of head length, 14.1% of body length, and greater than twice the diameter of the eye. The reason for such large nostrils is because females give off a species-specific smell that attracts males who rely on their huge nostrils to find them. Linophryne arborifera is found at depths between 750-2,200 m (2,460–7,215 ft) in all three major oceans of the world; specimens can reach 18.5 mm (0.72 in) long. There are about 60 of these little males in museum collections around the world.
Only the males have these large nostrils.