thumb
In
biologyBiology is the natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy...
, a
blowhole is the hole at the top of a
Cetacean'sThe order Cetacea includes whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea monster"...
head through which the animal breathes air. It is
homologousIn evolutionary biology, homology refers to any similarity between characteristics of organisms that is due to their shared ancestry. The word homologous derives from the ancient Greek ομολογειν, 'to agree'. There are examples in different branches of biology...
with the
nostrilA nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
of other
mammalMammals are a class of vertebrate animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair, three middle ear bones used in hearing, and a neocortex region in the brain.Mammals are divided into three main...
s. As whales reach the water surface to breathe, they will forcefully expel air through the blowhole. Not only is air expelled, but mucus and nitrogen from the animal's metabolism, which has been stored in the whale while diving. The exhalation is released into the comparably lower-pressure, colder atmosphere, and any water vapor condenses.
thumb
In
biologyBiology is the natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy...
, a
blowhole is the hole at the top of a
Cetacean'sThe order Cetacea includes whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea monster"...
head through which the animal breathes air. It is
homologousIn evolutionary biology, homology refers to any similarity between characteristics of organisms that is due to their shared ancestry. The word homologous derives from the ancient Greek ομολογειν, 'to agree'. There are examples in different branches of biology...
with the
nostrilA nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
of other
mammalMammals are a class of vertebrate animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair, three middle ear bones used in hearing, and a neocortex region in the brain.Mammals are divided into three main...
s. As whales reach the water surface to breathe, they will forcefully expel air through the blowhole. Not only is air expelled, but mucus and nitrogen from the animal's metabolism, which has been stored in the whale while diving. The exhalation is released into the comparably lower-pressure, colder atmosphere, and any water vapor condenses. This spray, known as the
blow, is often visible from far away as a white splash, which can also be partially caused by water resting on top of the blowhole.
Sound production
Air sacs just below the blowhole allow whales to produce sounds for
communication Communication is a process of transferring information from one entity to another. Communication processes are sign-mediated interactions between at least two agents which share a repertoire of signs and semiotic rules. Communication is commonly defined as "the imparting or interchange of...
and (for those species capable of it)
echolocationEcholocation, also called biosonar, is the biological sonar used by several animals such as dolphins, shrews, most bats, and most whales. The term was coined by Donald Griffin, who was the first to conclusively demonstrate its existence in bats...
. These air sacs are filled with air, which is then released again to produce sound in a similar fashion to releasing air from a balloon.
Anatomy
left
Baleen whaleThe baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea . Baleen whales are characterized by having baleen plates for filtering food from water, rather than having teeth. This distinguishes them from the other suborder of cetaceans,...
s have two blowholes positioned in a V-shape while
toothed whaleThe toothed whales form a suborder of the cetaceans, including sperm whales, beaked whales, orca, dolphins, and others. As the name suggests, the suborder is characterized by having teeth, rather than baleen as do animals in the other suborder of cetaceans, Mysticeti...
s have only one blowhole. The blowhole of a
sperm whaleThe sperm whale, , is a species of marine mammal in the order cetacea, a toothed whale with the largest brain of any animal. The whale was named after the milky-white waxy substance, spermaceti, found in its head and originally mistaken for sperm...
, a toothed whale, is located left of center in the frontal area of the snout, and is actually its left nostril, while the right nostril lacks an opening to the surface despite the fact that its nasal passage is otherwise well developed.
The
tracheaThe trachea, or windpipe, is a tube that connects to the pharynx or larynx, allowing the passage of air to the lungs. It is lined with pseudostratified ciliated columnar epithelium cells with mucosal goblet cells which produce mucus...
only connects to the blowhole and there is no connection to the
esophagusThe esophagus or oesophagus , sometimes known as the gullet, is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. The word esophagus is derived from the Latin œsophagus, which derives from the Greek word oisophagos , lit...
as with humans and most other mammals. Because of this, there is no risk of food accidentally ending up in the animal's
lungThe lung or pulmonary system is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart...
s, and likewise the animal cannot breathe through its mouth. As a consequence, whales don't have any pharyngeal reflex.