Balaenopteridae
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Rorquals () are the largest
group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...
of
baleen whale Baleen whales (), also known as whalebone whales, are marine mammals of the order (biology), parvorder Mysticeti in the infraorder Cetacea (whales, dolphins and porpoises), which use baleen plates (or "whalebone") in their mouths to sieve plankt ...
s, comprising the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Balaenopteridae, which contains nine extant species in two
genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...
. They include the largest known animal that has ever lived, the
blue whale The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known ever to have existed. The blue whale's long and slender body can ...
, which can reach , and the
fin whale The fin whale (''Balaenoptera physalus''), also known as the finback whale or common rorqual, is a species of baleen whale and the second-longest cetacean after the blue whale. The biggest individual reportedly measured in length, wi ...
, which reaches ; even the smallest of the group, the
northern minke whale The common minke whale or northern minke whale (''Balaenoptera acutorostrata'') is a species of minke whale within the suborder of baleen whales. It is the smallest species of the rorquals and the second smallest species of baleen whale. Althoug ...
, reaches . Rorquals take their name from French , which derives from the Norwegian word : the first element originated from the
Old Norse Old Norse, also referred to as Old Nordic or Old Scandinavian, was a stage of development of North Germanic languages, North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants ...
name for this type of whale, , probably related to the Norse word for "red", and the second from the Norse word ''hvalr'' meaning "whale" in general. The family name Balaenopteridae is from the
type genus In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearin ...
, ''
Balaenoptera ''Balaenoptera'' () is a genus of rorquals containing eight extant species. ''Balaenoptera'' comprises all but two of the extant species in its family (the humpback whale and gray whale); the genus is currently polyphyletic, with the two aforemen ...
''.


Characteristics

All members of the family have a series of longitudinal folds of skin running from below the mouth back to the navel (except the
sei whale The sei whale ( , ; ''Balaenoptera borealis'') is a baleen whale. It is one of ten rorqual species, and the third-largest member after the blue and fin whales. It can grow to in length and weigh as much as . Two subspecies are recognized: ...
and
common minke whale The common minke whale or northern minke whale (''Balaenoptera acutorostrata'') is a species of minke whale within the suborder of baleen whales. It is the smallest species of the rorquals and the second smallest species of baleen whale. Althoug ...
, which have shorter grooves). These furrows allow the mouth to expand immensely when feeding. These "pleated throat grooves" distinguish balaenopterids from other whales. Rorquals are slender and streamlined in shape, compared with their relatives the
right whale Right whales are three species of large baleen whales of the genus ''Eubalaena'': the North Atlantic right whale (''E. glacialis''), the North Pacific right whale (''E. japonica'') and the southern right whale (''E. australis''). They are class ...
s, and most have narrow, elongated flippers. They have a dorsal fin, situated about two-thirds the way back. Most rorquals feed by gulping in water, and then pushing it out through the
baleen Baleen is a filter feeder, filter-feeding system inside the mouths of baleen whales. To use baleen, the whale first opens its mouth underwater to take in water. The whale then pushes the water out, and animals such as krill are filtered by th ...
plates with their tongue; the exception is the
gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of , a weight of up to and lives between ...
, which gulps in and filters large amounts of marine sediments from the seafloor. They feed on
crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...
, such as
krill Krill ''(Euphausiids)'' (: krill) are small and exclusively marine crustaceans of the order (biology), order Euphausiacea, found in all of the world's oceans. The name "krill" comes from the Norwegian language, Norwegian word ', meaning "small ...
, but also on various fish, such as
herring Herring are various species of forage fish, belonging to the Order (biology), order Clupeiformes. Herring often move in large Shoaling and schooling, schools around fishing banks and near the coast, found particularly in shallow, temperate wate ...
s and
sardine Sardine and pilchard are common names for various species of small, oily forage fish in the herring suborder Clupeoidei. The term "sardine" was first used in English during the early 15th century; a somewhat dubious etymology says it com ...
s.
Gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...
in rorquals lasts 11–12 months, so that both mating and birthing occur at the same time of year. Cows give birth to a single calf, which is
weaned Weaning is the process of gradually introducing an infant human or other mammal to what will be its adult diet while withdrawing the supply of its mother's milk. In the UK, weaning primarily refers to the introduction of solid foods at 6 mont ...
after 6–12 months, depending on species. Of some species, adults live in small groups, or "pods" of two to five individuals. For example, humpback whales have a fluid social structure, often engaging behavioral practices in a pod, other times being solitary.


Distribution and habitat

Distribution is worldwide: the blue, fin, humpback, and the sei whales are found in all major oceans; the common (northern) and Antarctic (southern) minke whale species are found in all the oceans of their respective hemispheres; either of
Bryde's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The "complex" means the number and classification remain unclear because of a lack of definitive information and research. The c ...
and
Eden's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The " complex" means the number and classification remain unclear because of a lack of definitive information and research. The ...
occur in the
Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...
,
Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...
, and Indian oceans, being absent only from the cold waters of the
Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...
and
Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...
; and the gray whale is found in the northern Pacific Ocean, although it was also found in the Atlantic Ocean in historic times. Rice's whale has the smallest distribution of rorquals and possibly baleen whales in general, being
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to a small portion of the
Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
west of the
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
peninsula A peninsula is a landform that extends from a mainland and is only connected to land on one side. Peninsulas exist on each continent. The largest peninsula in the world is the Arabian Peninsula. Etymology The word ''peninsula'' derives , . T ...
and south of
Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...
and the
Florida panhandle The Florida panhandle (also known as West Florida and Northwest Florida) is the northwestern part of the U.S. state of Florida. It is a Salient (geography), salient roughly long, bordered by Alabama on the west and north, Georgia (U.S. state ...
, although it likely formerly had a much wider distribution in the Gulf. Most rorquals are strictly oceanic: the exceptions are the gray whale, Bryde's whale, Eden's whale, and Rice's whale (which are usually found close to shore all year round) and the
humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the monotypic taxon, only species in the genus ''Megaptera''. Adults range in length from and weigh u ...
(which is oceanic but passes close to shore when migrating). It is the largest and the smallest types — the blue whale and Antarctic minke whale — that occupy the coldest waters in the extreme south; the fin whale tends not to approach so close to the ice shelf; the sei whale tends to stay further north again. (In the northern hemisphere, where the continents distort weather patterns and
ocean current An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, sh ...
s, these movements are less obvious, although still present.) Within each species, the largest individuals tend to approach the poles more closely, while the youngest and fittest ones tend to stay in warmer waters before leaving on their annual migration. Most rorquals breed in tropical waters during the winter, then migrate back to the polar feeding grounds rich in
plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...
and krill for the short polar summer.


Feeding habits

As well as other methods, rorquals obtain prey by lunge-feeding on
bait ball A bait ball, or baitball, occurs when small fish swarm in a tightly packed spherical formation about a common centre. It is a last-ditch defensive measure adopted by small schooling fish when they are threatened by predators. Small schooling f ...
s. Lunge feeding is an extreme feeding method, where the whale accelerates to a high velocity and then opens its mouth to a large gape angle. This generates the water pressure required to expand its mouth and engulf and filter a huge amount of water and fish. In contrast to typical lunge feeding, Gray whales employ a unique suction feeding strategy to capture prey near or on the sea bottom. Rorquals have a number of anatomical features that enable them to do this, including bilaterally separate
mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...
s, throat pleats that can expand to huge size, and a unique sensory organ consisting of a bundle of
mechanoreceptor A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are located on sensory neurons that convert mechanical pressure into action potential, electrical signals tha ...
s that helps their brains to coordinate the engulfment action. Furthermore, their large nerves are flexible so that they can stretch and recoil. In fact, they give rorquals the ability to open their mouths so wide that they would be capable of taking in water at volumes greater than their own sizes. These nerves are packed into a central core area that is surrounded by
elastin Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...
fibers. Opening the mouth causes the nerves to unfold, and they snap back after the mouth is closed. According to Potvin and Goldbogen, lunge feeding in rorquals represents the largest biomechanical event on Earth.


Taxonomy

Formerly, the rorqual family Balaenopteridae was split into two subfamilies, the Balaenopterinae and the Megapterinae, with each subfamily containing one genus, ''
Balaenoptera ''Balaenoptera'' () is a genus of rorquals containing eight extant species. ''Balaenoptera'' comprises all but two of the extant species in its family (the humpback whale and gray whale); the genus is currently polyphyletic, with the two aforemen ...
'' and '' Megaptera'', respectively. However, the
phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...
of the various rorqual species shows the current division is
paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
, and in 2005, the division into subfamilies was dropped. Two genetic studies, one in 2018 and one in 2020, suggest that the
gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of , a weight of up to and lives between ...
(''Eschrichtius robustus'') be counted among the rorquals, being more derived than the two
minke whale The minke whale (), or lesser rorqual, is a species complex of baleen whale. The two species of minke whale are the common (or northern) minke whale and the Antarctic (or southern) minke whale. The minke whale was first described by the Danish na ...
s but basal to the
humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the monotypic taxon, only species in the genus ''Megaptera''. Adults range in length from and weigh u ...
,
fin whale The fin whale (''Balaenoptera physalus''), also known as the finback whale or common rorqual, is a species of baleen whale and the second-longest cetacean after the blue whale. The biggest individual reportedly measured in length, wi ...
, and the other taxa classified in ''
Balaenoptera ''Balaenoptera'' () is a genus of rorquals containing eight extant species. ''Balaenoptera'' comprises all but two of the extant species in its family (the humpback whale and gray whale); the genus is currently polyphyletic, with the two aforemen ...
''. The discovery of a new species of balaenopterid, Omura's whale (''Balaenoptera omurai''), was announced in November 2003, which looks similar to, but smaller than, the
fin whale The fin whale (''Balaenoptera physalus''), also known as the finback whale or common rorqual, is a species of baleen whale and the second-longest cetacean after the blue whale. The biggest individual reportedly measured in length, wi ...
; individuals of this species were found in Indo-Pacific waters. The discovery of the highly endangered Rice's whale was announced in 2021 after a genetic study found it to be distinct from
Bryde's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The "complex" means the number and classification remain unclear because of a lack of definitive information and research. The c ...
; this species is known from a small portion of the northeastern
Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
.


Extant species

* Family Balaenopteridae: Rorquals ** ''
Balaenoptera ''Balaenoptera'' () is a genus of rorquals containing eight extant species. ''Balaenoptera'' comprises all but two of the extant species in its family (the humpback whale and gray whale); the genus is currently polyphyletic, with the two aforemen ...
'' ***
Fin whale The fin whale (''Balaenoptera physalus''), also known as the finback whale or common rorqual, is a species of baleen whale and the second-longest cetacean after the blue whale. The biggest individual reportedly measured in length, wi ...
, ''Balaenoptera physalus'' **** Northern fin whale, ''Balaenoptera physalus physalus'' **** Southern fin whale, ''Balaenoptera physalus quoyi'' ***
Sei whale The sei whale ( , ; ''Balaenoptera borealis'') is a baleen whale. It is one of ten rorqual species, and the third-largest member after the blue and fin whales. It can grow to in length and weigh as much as . Two subspecies are recognized: ...
, ''Balaenoptera borealis'' ***
Bryde's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The "complex" means the number and classification remain unclear because of a lack of definitive information and research. The c ...
, ''Balaenoptera edeni'' ****
Eden's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The " complex" means the number and classification remain unclear because of a lack of definitive information and research. The ...
, ''Balaenoptera edeni edeni'' *** Rice's whale, ''Balaenoptera ricei'' ***
Blue whale The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known ever to have existed. The blue whale's long and slender body can ...
, ''Balaenoptera musculus'' ****
Pygmy blue whale The pygmy blue whale (''Balaenoptera musculus brevicauda'') is a subspecies of the blue whale (''Balaenoptera musculus'') found in the Indian Ocean and the Southern Pacific Ocean. Taxonomy The pygmy blue whale formed from a founder group of An ...
, ''Balaenoptera musculus brevicauda'' ***
Common minke whale The common minke whale or northern minke whale (''Balaenoptera acutorostrata'') is a species of minke whale within the suborder of baleen whales. It is the smallest species of the rorquals and the second smallest species of baleen whale. Althoug ...
, ''Balaenoptera acutorostrata'' *** Antarctic minke whale, ''Balaenoptera bonaerensis'' *** Omura's whale, ''Balaenoptera omurai'' ** '' Megaptera'' ***
Humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the monotypic taxon, only species in the genus ''Megaptera''. Adults range in length from and weigh u ...
, ''Megaptera novaeangliae''


Fossil genera

**'' Archaebalaenoptera'' **'' Archaeschrichtius'' **'' Cetotheriophanes'' ** '' Diunatans'' **''
Eschrichtioides ''Eschrichtioides'' is an extinct genus of baleen whale known from the early Pliocene of Northern Italy. Its type species, ''E. gastaldii'', had a complex taxonomic history, starting as a cetothere, then as an extinct member of '' Balaenoptera' ...
'' **'' Gricetoides'' **'' Incakujira'' **'' Miobalaenoptera'' ** '' Nehalaennia'' **'' Parabalaenoptera'' ** '' Plesiobalaenoptera'' ** '' Plesiocetus'' ** '' Praemegaptera'' ** ''
Protororqualus ''Protororqualus'' is a genus of extinct rorqual from the late Pliocene (Piacenzian, ) of Mount Pulgnasco, Italy (: paleocoordinates ). The analysis made by identified ''Protororqualus'' as a late representative of the rorquals which survived i ...
''


Alternative generic taxonomy for living rorquals

In 2012, the following alternate taxonomy was presented: * ''
Balaenoptera ''Balaenoptera'' () is a genus of rorquals containing eight extant species. ''Balaenoptera'' comprises all but two of the extant species in its family (the humpback whale and gray whale); the genus is currently polyphyletic, with the two aforemen ...
'' **
Fin whale The fin whale (''Balaenoptera physalus''), also known as the finback whale or common rorqual, is a species of baleen whale and the second-longest cetacean after the blue whale. The biggest individual reportedly measured in length, wi ...
, ''Balaenoptera physalus'' * '' Megaptera'' **
Humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the monotypic taxon, only species in the genus ''Megaptera''. Adults range in length from and weigh u ...
, ''Megaptera novaeangliae'' * '' Pterobalaena'' **
Common minke whale The common minke whale or northern minke whale (''Balaenoptera acutorostrata'') is a species of minke whale within the suborder of baleen whales. It is the smallest species of the rorquals and the second smallest species of baleen whale. Althoug ...
, ''Pterobalaena acutorostrata'' ** Antarctic minke whale, ''Pterobalaena bonaerensis'' * '' Rorqualus'' **
Sei whale The sei whale ( , ; ''Balaenoptera borealis'') is a baleen whale. It is one of ten rorqual species, and the third-largest member after the blue and fin whales. It can grow to in length and weigh as much as . Two subspecies are recognized: ...
, ''Rorqualus borealis'' **
Bryde's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The "complex" means the number and classification remain unclear because of a lack of definitive information and research. The c ...
, ''Rorqualus brydei'' **
Eden's whale Bryde's whale ( ), or the Bryde's whale complex, putatively comprises three species of rorqual and possibly four. The " complex" means the number and classification remain unclear because of a lack of definitive information and research. The ...
, ''Rorqualus edeni'' **
Blue whale The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known ever to have existed. The blue whale's long and slender body can ...
, ''Rorqualus musculus'' ** Omura's whale, ''Rorqualus omurai''


References


Notes


Sources

*


External links

* * * {{Authority control Baleen whales Taxa named by John Edward Gray