Fin whales, the largest family of baleen whales, move through the water with their mouths wide open to feed. They suck not only large amounts of their small prey, but also a huge amount of water. During the so-called lunge, their mouths are subjected to tremendous physical forces.
Marine biologists at the University of British Columbia have investigated how whales do this without suffocating or drowning. They discovered a structure blocking the channel between the mouth and the pharynx to protect the pharyngeal entrance and airways. It is assumed that “gag mouthful” occurs in all whales that feed in the same way.
The mechanism of the impulse was already known, but until now researchers remained unknown about how to swallow prey such as krill. The anatomy of the larynx was known, but little was known about the rest of the pharynx, the conductor between the respiratory and digestive systems.
The researchers studied the tissues of dead whales. Analyzes have shown that the oral obturator is part of the soft palate and can move backward and upward to block the nasal passages. This forced the researchers to examine the larynx, because they expect it to be at the site of the oral plug during breathing, but not during swallowing. It was located at the bottom of the pharynx, where the laryngeal cartilage closes to protect this cavity. A muscular sac in the lower part of the larynx is pushed up into the lumen of the larynx to completely close the lower airways.
According to the researchers, no such structure as the oral plug has been reported in any other animal. There are very few lungy animals that feed by devouring prey and water. Researcher Kelsey Gill says: ‘The mouth muzzle may be specific to fin whales’.†
Source: University of British Columbia, Vancouver, Canada