A Dolphins Whiskers
All mammals have hair at some point in their lives, including dolphins. They are born with whiskers on their upper jaw, approximately 6 on either side of their rostrum.
They generally fall out within a week after birth due to water pressure as they learn to swim. This is one of a calf’s features that enable us to identify how ‘newborn’ they are.
When the whiskers fall out, they are left with a row of tiny pits known as ‘vibrissal crypts’ and these remain for their entire life.
At the time of birth, the whiskers help a dolphin calf to be able to sense things in their environment, like where to nurse their mother. What use do the whisker pits have later in life though?
No studies of their functions have been done on the Indo-Pacific bottlenose dolphin that we have here in Mandurah, however studies on another species of dolphin – the Guiana dolphins – which have similar but larger pits found them to be extremely useful.
Studies by Nicole Czech-Damal from the University of Hamburg discovered that the vibrissal crypts on the Guiana dolphins function as a sensory organ, detecting electric fields used by prey such as fish. This is known as electroreception and supplements their invaluable sonar ability (ecolocation) which they navigate and hunt with.
Guiana dolphins live in shallow waters of coasts and estuaries, where silt and mud make the waters murky – similar conditions to the Peel-Harvey Estuary at times of the year. Their electric sense can help them to cut through the murk and assist them in locating buried fish which put off electric fields.
For now, it’s not certain if bottlenose or other species of dolphins use their vibrissal crypts in the same way that the Guiana dolphin can. There are certain behaviours however that lead us to believe bottlenose dolphins may detect electric fields using their vibrissal crypts such as digging for food in the ground, where electroreception would be incredibly useful.