Misplaced Pages

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99-457: Depending on the species, a baleen plate can be 0.5 to 3.5 m (1.6 to 11.5 ft) long, and weigh up to 90 kg (200 lb). Its hairy fringes are called baleen hair or whalebone hair. They are also called baleen bristles, which in sei whales are highly calcified, with calcification functioning to increase their stiffness. Baleen plates are broader at the gumline (base). The plates have been compared to sieves or Venetian blinds . As

198-449: A buttress of bone in the upper jaw beneath the eyes, and loose lower jaw bones at the chin. Baleen is believed to have evolved around 30 million years ago, possibly from a hard, gummy upper jaw, like the one a Dall's porpoise has; it closely resembles baleen at the microscopic level. The initial evolution and radiation of baleen plates is believed to have occurred during Early Oligocene when Antarctica broke off from Gondwana and

297-541: A choriovitelline placenta (which can be thought of as something between a monotreme egg and a "true" placenta), in which the egg's yolk sac supplies a large part of the embryo's nutrition but also attaches to the uterine wall and takes nutrients from the mother's bloodstream. However, bandicoots also have a rudimentary chorioallantoic placenta, similar to those of placental mammals. The fetus usually develops fully in placental mammals and only partially in marsupials including kangaroos and opossums . In marsupials,

396-516: A 16 m (52 ft) female that had stranded on the coast of France the previous year (this was later identified as a juvenile fin whale, Balaenoptera physalus ). In 1846, the English zoologist John Edward Gray , ignoring Lesson's designation, named Rudolphi's specimen Balaenoptera laticeps , which others followed. In 1865, British zoologist William Henry Flower named a 14 m (46 ft) specimen that had been obtained from Pekalongan , on

495-633: A calf typically measures 4.4–4.5 m (14–15 ft) in length. In the Northern Hemisphere, males reach up to 17.1 m (56 ft) and females up to 18.6 m (61 ft), while in the Southern Hemisphere males reach a maximum of 18.6 m (61 ft) and females of 19.5 m (64 ft). The authenticity of an alleged 22 m (72 ft) female caught 80 km (50 mi) northwest of St. Kilda in July 1911

594-431: A hybrid to baleen. It is known that modern mysticetes have teeth initially and then develop baleen plate germs in utero , but lose their dentition and have only baleen during their juvenile years and adulthood. However, developing mysticetes do not produce tooth enamel because at some point this trait evolved to become a pseudogene . This is likely to have occurred about 28 million years ago and proves that dentition

693-425: A lifespan of 70 years. It is a filter feeder , with its diet consisting primarily of  copepods ,  krill , and other zooplankton . It is typically solitary or can be found in groups numbering half a dozen. During the breeding period, a mating pair will remain together. Sei whale vocalizations usually lasts half a second, and occurs at 240–625 hertz. Following large-scale  commercial whaling  during

792-614: A material for various human uses, baleen is usually called whalebone , which is a misnomer . The word " baleen " derives from the Latin bālaena , related to the Greek phalaina – both of which mean "whale". The oldest true fossils of baleen are only 15 million years old because baleen rarely fossilizes, but scientists believe it originated considerably earlier than that. This is indicated by baleen-related skull modifications being found in fossils from considerably earlier, including

891-578: A peak in "20- to 35-Hz irregular repetition interval" downswept pulses described from seafloor recordings off Oahu , which had previously been attributed to fin whales. Between 2005 and 2007, low frequency downswept vocalizations were recorded in the Great South Channel, east of Cape Cod , Massachusetts , which were associated with the presence of sei whales. These calls averaged 82.3 Hz down to 34 Hz over about 1.4 seconds in duration. This call has also been reported from recordings in

990-524: A possible link between these areas, but the lack of other tag recovery data makes these two cases inconclusive. Occurrences within the Gulf of California have been fewer. In Sea of Japan and Sea of Okhotsk , whales are not common, although whales were more commonly seen than today in southern part of Sea of Japan. There had been a sighting in Golden Horn Bay , and whales were much more abundant in

1089-405: A tall, sickle -shaped dorsal fin that ranges in height from 38–90 cm (15–35 in) and averages 53–56 cm (21–22 in), about two-thirds of the way back from the tip of the rostrum. Dorsal fin shape, pigmentation pattern, and scarring have been used to a limited extent in photo-identification studies. The tail is thick and the fluke , or lobe, is relatively small in relation to

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1188-609: A total of 2,574 whales were taken from the Hvalfjörður whaling station between 1948 and 1985. Since the late 1960s to early 1970s, the sei whale was second only to the fin whale as the preferred target of Icelandic whalers, with meat in greater demand than whale oil , the prior target. Small numbers were taken off the Iberian Peninsula , beginning in the 1920s by Spanish whalers, off the Nova Scotian shelf in

1287-601: A transition state between odontocetes and mysticetes. This intermediate step is further supported by evidence of other changes that occurred with the evolution of baleen that make it possible for the organisms to survive using filter feeding, such as a change in skull structure and throat elasticity . It would be highly unlikely for all of these changes to occur at once. Therefore, it is proposed that Oligocene aetiocetids possess both ancestral and descendant character states regarding feeding strategies. This makes them mosaic taxa , showing that either baleen evolved before dentition

1386-412: A tubular structure with a hollow medulla (inner core) enclosed by a tubular layer with a diameter varying from 60 to 900 microns, which had approximately 2.7 times higher calcium content than the outer solid shell. The elastic modulus in the longitudinal direction and the transverse direction are 270 megapascals ( MPa ) and 200 MPa, respectively. This difference in the elastic moduli could be attributed to

1485-529: A vocalizing whale would perceive a volume roughly equivalent to the volume of a jackhammer operating two meters away. In November 2002, scientists recorded calls in the presence of sei whales off Maui . All the calls were downswept tonal calls, all but two ranging from a mean high frequency of 39.1 Hz down to 21 Hz of 1.3 second duration – the two higher frequency downswept calls ranged from an average of 100.3 Hz to 44.6 Hz over 1 second of duration. These calls closely resembled and coincided with

1584-685: Is 14 m (46 ft) and of an adult female is 14.5 m (48 ft). In the Southern Hemisphere, they average 14.5 m (48 ft) and 15 m (49 ft), in males and females, respectively. In the North Pacific, males weigh an average of 15 t (15 long tons; 17 short tons) and females 18.5 t (18.2 long tons; 20.4 short tons). North Atlantic sei whale males average 15.5 t (15.3 long tons; 17.1 short tons) and females 17 t (17 long tons; 19 short tons). Southern Hemisphere whales average 17–18.5 t (16.7–18.2 long tons; 18.7–20.4 short tons) in body weight. Very little

1683-403: 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 19.5 m (64 ft) in length and weigh as much as 28 t (28 long tons; 31 short tons). Two subspecies are recognized: B. b. borealis and B. b. schlegelii . The whale's ventral surface has sporadic markings ranging from light grey to white, and its body

1782-489: Is a filter feeder , using its baleen plates to obtain its food by opening its mouth, engulfing or skimming large amounts of the water containing the food, then straining the water out through the baleen, trapping any food items inside its mouth. The sei whale feeds near the surface of the ocean, swimming on its side through swarms of prey to obtain its average of about 900 kg (2,000 lb) of food each day. For an animal of its size, its preferred prey lies low within

1881-567: Is an ancestral state of mysticetes. Using parsimony to study this and other ancestral characters suggests that the common ancestor of aetiocetids and edentulous mysticetes evolved lateral nutrient foramina , which are believed to have provided blood vessels and nerves a way to reach developing baleen. Further research suggests that the baleen of Aetiocetus was arranged in bundles between widely spaced teeth. If true, this combination of baleen and dentition in Aetiocetus would act as

1980-435: Is covered by a sheet-like fold of peritoneum, the broad ligament . The uterus has three layers, which together form the uterine wall . From innermost to outermost, these layers are the endometrium , myometrium , and perimetrium . The endometrium is the inner epithelial layer , along with its mucous membrane , of the mammalian uterus. It has a basal layer and a functional layer; the functional layer thickens and then

2079-476: Is doubted. Five specimens taken off Iceland exceeded 14.6 m (48 ft) in length. The longest measured during JARPN II cruises in the North Pacific were a 16.32 m (53.5 ft) female and a 15 m (49 ft) male. In the North Pacific, adult males average 13.7 m (45 ft) and adult females 15 m (49 ft). In the North Atlantic, the average length of an adult male

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2178-454: Is known about the sei whale social structure . They have been documented traveling alone or in pods of up to six individuals; larger groups may assemble at particularly abundant feeding grounds. During the southern Gulf of Maine influx in mid-1986, groups of at least three sei whales were observed "milling" on four occasions – i.e. moving in random directions, rolling, and remaining at the surface for over 10 minutes. One whale would always leave

2277-407: Is known as the junctional zone , which becomes thickened in adenomyosis . The perimetrium is a serous layer of visceral peritoneum . It covers the outer surface of the uterus. Surrounding the uterus is a layer or band of fibrous and fatty connective tissue called the parametrium that connects the uterus to other tissues of the pelvis. Commensal and mutualistic organisms are present in

2376-507: Is not a remarkable diver, reaching relatively shallow depths for 5 to 15 minutes. Between dives, the whale surfaces for a few minutes, remaining visible in clear, calm waters, with blows occurring at intervals of about 60 seconds (range: 45–90 sec.). When about to dive, the sei whale usually just sinks below the surface; only the dorsal fin and blowholes protrude. The whale is generally less active on water surfaces than other whale species; they rarely exhibit lobtail behaviour. This rorqual

2475-443: Is pointed and the pectoral fins are relatively short, only 9–10% of body length, and pointed at the tips. Sei whales have a solitary ridge extending from the tip of the rostrum to the paired blowholes that are a distinctive characteristic of baleen whales. Its skin is often marked by pits or wounds, which after healing become white scars. These are now known to be caused by cookie-cutter sharks ( Isistius brasiliensis ). It has

2574-438: Is shed during the menstrual cycle or estrous cycle . During pregnancy , the uterine glands and blood vessels in the endometrium further increase in size and number and form the decidua . Vascular spaces fuse and become interconnected, forming the placenta , which supplies oxygen and nutrition to the embryo and fetus . The myometrium of the uterus mostly consists of smooth muscle . The innermost layer of myometrium

2673-435: Is the organ in the reproductive system of most female mammals , including humans, that accommodates the embryonic and fetal development of one or more fertilized eggs until birth . The uterus is a hormone -responsive sex organ that contains glands in its lining that secrete uterine milk for embryonic nourishment. (The term uterus is also applied to analogous structures in some non-mammalian animals.) In

2772-436: Is the most commonly performed gynecological surgical procedure . Uterus transplantations have been successfully carried out in a number of countries. The transplant is intended to be temporary – recipients will have to undergo a hysterectomy after one or two successful pregnancies. This is done to avoid the need to take immunosuppressive drugs for life with a consequent increased risk of infection. The procedure remains

2871-400: Is true that many early baleen whales also had teeth, these were probably used only peripherally, or perhaps not at all (again like Dall's porpoise, which catches squid and fish by gripping them against its hard upper jaw). Intense research has been carried out to sort out the evolution and phylogenetic history of mysticetes, but much debate surrounds this issue. A whale's baleen plates play

2970-460: Is typically a dark steel grey with irregular light grey to white markings on the ventral surface, or towards the front of the lower body. The whale has a relatively short series of 32–60 pleats or grooves along its ventral surface that extend halfway between the pectoral fins and umbilicus (in other species it usually extends to or past the umbilicus), restricting the expansion of the buccal cavity during feeding compared to other species. The rostrum

3069-458: Is usually dark steel grey in colour. It is among the fastest of all  cetaceans , and can reach speeds of up to 50 km/h (31 mph) over short distances.  It inhabits most oceans and adjoining seas, and prefers deep offshore waters. It avoids polar  and tropical waters and semi-enclosed bodies of water. The sei whale migrates annually from cool, subpolar waters in summer to temperate , subtropical waters in winter with

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3168-485: The Antarctic Circumpolar Current was formed, increasing productivity of ocean environments. This occurred because the current kept warm ocean waters away from the area that is now Antarctica, producing steep gradients in temperature, salinity , light, and nutrients, where the warm water meets the cold. The transition from teeth to baleen is proposed to have occurred stepwise , from teeth to

3267-742: The Charlie-Gibbs Fracture Zone (CGFZ) between April and June 2005. It appeared to "hitch a ride" on prevailing currents, with erratic movements indicative of feeding behavior in five areas, in particular the CGFZ, an area of known high sei whale abundance as well as high copepod concentrations. Seven whales tagged off Faial and Pico from May to June in 2008 and 2009 made their way to the Labrador Sea, while an eighth individual tagged in September 2009 headed southeast – its signal

3366-561: The Japanese flying squid , Todarodes pacificus pacificus , and small fish, including anchovies ( Engraulis japonicus and E. mordax ), sardines ( Sardinops sagax ), Pacific saury ( Cololabis saira ), mackerel ( Scomber japonicus and S. australasicus ), jack mackerel ( Trachurus symmetricus ) and juvenile rockfish ( Sebastes jordani ). Off central California, they mainly feed on anchovies between June and August, and on krill ( Euphausia pacifica ) during September and October. In

3465-680: The North Atlantic , it feeds primarily on calanoid copepods , specifically Calanus finmarchicus , with a secondary preference for euphausiids , in particular Meganyctiphanes norvegica and Thysanoessa inermis . In the North Pacific , it feeds on similar zooplankton, including the copepod species Neocalanus cristatus , N. plumchrus , and Calanus pacificus , and euphausiid species Euphausia pacifica , E. similis , Thysanoessa inermis , T. longipes , T. gregaria and T. spinifera . In addition, it eats larger organisms, such as

3564-613: The fallopian tubes and the uterus. In humans, the lower segments of the two ducts fuse to form a single uterus; in cases of uterine malformations this fusion may be disturbed. The different uterine morphologies among the mammals are due to varying degrees of fusion of the Müllerian ducts. Various congenital conditions of the uterus can develop in utero . Though uncommon, some of these are didelphic uterus , bicornate uterus and others. See also List of related male and female reproductive organs . The primary reproductive function of

3663-445: The food chain ; this includes zooplankton and small fish. The whale's diet preferences has been determined from stomach analyses, direct observation of feeding behavior, and analyzing fecal matter collected near them, which appears as a dilute brown cloud. The feces are collected in nets and DNA is separated, individually identified, and matched with known species. The whale competes for food against different baleen whales . In

3762-420: The fundus – the uppermost rounded portion of the uterus above the openings of the fallopian tubes , the body , the cervix , and the cervical canal . The cervix protrudes into the vagina . The uterus is held in position within the pelvis by ligaments , which are part of the endopelvic fascia . These ligaments include the pubocervical ligaments , the cardinal ligaments , and the uterosacral ligaments . It

3861-480: The humpback whale , the blue whale , Bryde's whale , the fin whale , and the minke whale . Rorquals take their name from the Norwegian word røyrkval , meaning "furrow whale", because family members have a series of longitudinal pleats or grooves on the anterior half of their ventral surface. Balaenopterids diverged from the other families of suborder Mysticeti , also called the whalebone whales, as long ago as

3960-417: The interspinal line . The uterus is mobile and moves posteriorly under the pressure of a full bladder, or anteriorly under the pressure of a full rectum. If both are full, it moves upwards. Increased intra-abdominal pressure pushes it downwards. The mobility is conferred to it by a musculo-fibrous apparatus that consists of suspensory and sustentacular parts. Under normal circumstances, the suspensory part keeps

4059-693: The lesser fin whale because it somewhat resembles the fin whale. On 21 February 1819, Swedish-born German naturalist Karl Rudolphi initially identified a 9.8 m (32 ft) whale stranded near Grömitz , in Schleswig-Holstein , as Balaena rostrata ( Balaenoptera acutorostrata ). In 1823, the French naturalist Georges Cuvier described Rudolphi's specimen under the name "rorqual du Nord". In 1828, Rene Lesson translated this term into Balaenoptera borealis , basing his designation partly on Cuvier's description of Rudolphi's specimen and partly on

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4158-483: The paramesonephric ducts , which fuse into the single organ known as a simplex uterus. The uterus has different forms in many other animals and in some it exists as two separate uteri known as a duplex uterus. In medicine and related professions, the term uterus is consistently used, while the Germanic -derived term womb is commonly used in everyday contexts. Events occurring within the uterus are described with

4257-426: The platypus and the echidnas , either the term uterus or oviduct is used to describe the same organ, but the egg does not develop a placenta within the mother and thus does not receive further nourishment after formation and fertilization . Marsupials have two uteri, each of which connect to a lateral vagina and both use a third, middle "vagina", which functions as the birth canal. Marsupial embryos form

4356-413: The uterotubal junction . The fertilized egg is carried to the uterus along the fallopian tube. It will have divided on its journey to form a blastocyst that will implant itself into the lining of the uterus – the endometrium , where it will receive nutrients and develop into the embryo proper, and later fetus , for the duration of the pregnancy . In the human embryo , the uterus develops from

4455-512: The "sei whale" caught off Gabon in 1952 were actually Bryde's whales, based on examination of their baleen plates. The only confirmed historical record is the capture of a 14 m (46 ft) female, which was brought to the Cap Lopez whaling station in Gabon in September 1950. During cetacean sighting surveys off Angola between 2003 and 2006, only a single confirmed sighting of two individuals

4554-708: The 2001 meeting of the IWC Scientific Committee, 32 scientists submitted a document expressing their belief that the Japanese program lacked scientific rigor and would not meet minimum standards of academic review . In 2010, a Los Angeles exclusive sushi restaurant confirmed to be serving sei whale meat was closed by its owners after a covert investigation and protests lead to prosecution by authorities for handling an endangered/protected species. Uterus The uterus (from Latin uterus , pl. : uteri or uteruses) or womb ( / w uː m / )

4653-600: The Bryde's whale. Exceptional individuals may resemble a fin whale, which leads to confusion. They are usually differentiated from the fin whale by the colour of their head. Contrary to the fin whale's smooth rostrum, the sei whale's rostrum is curved. The sei whale is the third-largest balaenopterid, after the blue whale and the fin whale . Adults usually weigh between 15–20 t (15–20 long tons; 17–22 short tons). They exhibit sexual dimorphism , with females outweighing and being longer than their male counterparts. At birth,

4752-605: The Gulf of Maine, New England shelf waters, the mid-Atlantic Bight, and in Davis Strait . It likely functions as a contact call. BBC News quoted Roddy Morrison, a former whaler active in South Georgia, as saying, "When we killed the sei whales, they used to make a noise, like a crying noise. They seemed so friendly, and they'd come round and they'd make a noise, and when you hit them, they cried really. I didn't think it

4851-427: The North Atlantic between 1885 and 1984, 14,295 sei whales were taken. They were hunted in large numbers off the coasts of Norway and Scotland beginning in the late 19th and early 20th centuries, and in 1885 alone more than 700 were caught off Finnmark . Their meat was a popular Norwegian food. The meat's value made the hunting of this difficult-to-catch species profitable in the early twentieth century. In Iceland,

4950-606: The North Atlantic, its range extends from southern Europe or northwestern Africa to Norway, and from the southern United States to Greenland . The southernmost confirmed records are strandings along the northern Gulf of Mexico and in the Greater Antilles . It rarely enters the Mediterranean Sea and the Gulf of Mexico, which are both considered to be small waterbodies. Sei whales are pelagic and are typically found in basins in oceans or open seas. In

5049-709: The North Pacific began in the early 1960s, with catches averaging 3,643 per year from 1963 to 1974 (total 43,719; annual range 1,280–6,053). In 1971, after a decade of high catches, it became scarce in Japanese waters, ending commercial whaling in the country by 1975. Off the coast of North America, sei whales were hunted off British Columbia from the late 1950s to the mid-1960s, when the number of whales captured dropped to around 14 per year. More than 2,000 were caught in British Columbian waters between 1962 and 1967. Between 1957 and 1971, California shore stations processed 386 whales. Commercial Sei whaling ended in

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5148-566: The North Pacific, it ranges from 20°N to 23°N latitude in the winter, and from 35°N to 50°N latitude in the summer. Approximately 75% of the North Pacific population lives east of the International Date Line . As of February 2017 , the U.S. National Marine Fisheries Service estimated that the eastern North Pacific population stood at 374 whales. Two whales tagged in deep waters off California were later recaptured off Washington and British Columbia , revealing

5247-591: The South Atlantic and southern Indian Oceans and 45°S and 60°S in the South Pacific, while winter distribution is poorly known, with former winter whaling grounds being located off northeastern Brazil ( 7°S ) and Peru ( 6°S ). The majority of the "sei" whales caught off Angola and Congo, as well as other nearby areas in equatorial West Africa, are thought to have been predominantly misidentified Bryde's whales . For example, Ruud (1952) found that 42 of

5346-438: The Southern Hemisphere, males average 13.6 m (45 ft) and females 14 m (46 ft). The average age of sexual maturity of both sexes is 8–10 years. The whales can reach ages up to 70 years. The sei whale makes long, loud, low-frequency sounds. Relatively little is known about specific calls, but in 2003, observers noted sei whale calls in addition to sounds that could be described as "growls" or "whooshes" off

5445-535: The Southern Hemisphere, prey species include the copepods Neocalanus tonsus , Calanus simillimus , and Drepanopus pectinatus , as well as the euphausiids Euphausia superba and Euphausia vallentini and the pelagic amphipod Themisto gaudichaudii . Ectoparasites and epibiotics are rare on sei whales. Species of the parasitic copepod Pennella were only found on 8% of sei whales caught off California and 4% of those taken off South Georgia and South Africa. The pseudo-stalked barnacle Xenobalanus globicipitis

5544-595: The absence of fertilization, triggers the shedding of the functional layer of the endometrium. This layer is broken down, shed, and restored in anticipation of the next menstrual cycle. The average bleeding duration during menses is 5-7 days after which the menstrual cycle begins again. During pregnancy , the growth rate of the fetus can be assessed by measuring the fundal height . Some pathological states include: Uterine malformations are mainly congenital malformations , and include uterus didelphys , bicornuate uterus and septate uterus . Congenital absence of

5643-538: The baleen of sei whales caught off California, South Georgia, South Africa, and Finnmark. The ciliate protozoan Haematophagus was commonly found in the baleen of sei whales taken off South Georgia (nearly 85%). They often carry heavy infestations of acanthocephalans (e.g. Bolbosoma turbinella , which was found in 40% of sei whales sampled off California; it was also found in individuals off South Georgia and Finnmark) and cestodes (e.g. Tetrabothrius affinis , found in sei whales off California and South Georgia) in

5742-429: The baleen, thus sieving out the prey, which it then swallows. Whale baleen is the mostly mineralized keratin-based bio-material consisting of parallel plates suspended down the mouth of the whale. Baleen's mechanical properties of being strong and flexible made it a popular material for numerous applications requiring such a property (see Human uses section). The basic structure of the whale baleen has been described as

5841-444: The breeding period, a mating pair will remain together. A newborn is weaned from its mother at 6–9 months of age, when it is 8–9 m (26–30 ft) long, so weaning takes place at the summer or autumn feeding grounds. Females reproduce every 2–3 years, usually to a single calf. In the Northern Hemisphere, males are usually 12.8–12.9 m (42–42 ft) and females 13.3–13.5 m (44–44 ft) at sexual maturity, while in

5940-537: The coast of the Antarctic Peninsula . Many calls consisted of multiple parts at different frequencies. This combination distinguishes their calls from those of other whales. Most calls last about a second, and occur in the 37–98 hertz range, well within the range of human hearing. The maximum volume of the vocal sequences is reported as 156 decibels relative to 1 micropascal (μPa) at a reference distance of one metre. An observer situated one metre from

6039-727: The compressive response. Crack formation is also different for both the transverse and longitudinal orientation. For the transverse direction, cracks are redirected along the tubules, which enhances the baleen's resistance to fracture and once the crack enters the tubule it is then directed along the weaker interface rather than penetrating through either the tubule or lamellae. People formerly used baleen (usually referred to as "whalebone") for making numerous items where flexibility and strength were required, including baskets , backscratchers , collar stiffeners , buggy whips , parasol ribs, switches, crinoline petticoats, farthingales , busks , and corset stays , but also pieces of armour. It

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6138-555: The continental slope northward in spring. Large females lead the northward migration and reach the Denmark Strait earlier and more reliably than other sexes and classes, arriving in mid-July and remaining through mid-September. In some years, males and younger females remain at lower latitudes during the summer. Despite knowing some general migration patterns, exact routes are incompletely known and scientists cannot readily predict exactly where groups will appear from one year to

6237-523: The eastern North Pacific in 1971. A total of 152,233 were taken in the Southern Hemisphere between 1910 and 1979. Whaling in southern oceans originally targeted humpback whales. By 1913, this species became rare, and the catch of fin and blue whales began to increase. As these species likewise became scarce, sei whale catches increased rapidly in the late 1950s and early 1960s. The catch peaked in 1964–65 at over 20,000 sei whales, but by 1976, this number had dropped to below 2,000 and commercial whaling for

6336-424: The embryo, which grows through embryonic and fetal development until childbirth . During this process, the uterus grows to accommodate the growing fetus. When normal labor begins, the uterus forcefully contracts as the cervix dilates, which results in delivery of the infant. In the absence of pregnancy, menstruation occurs. The withdrawal of female sex hormones, estrogen and progesterone , which occurs in

6435-471: The group during or immediately after such socializing bouts. The sei whale is among the fastest cetaceans . The American naturalist Roy Chapman Andrews compared the sei whale to the cheetah , because it can swim at great speeds "for a few hundred yards", but it "soon tires if the chase is long" and "does not have the strength and staying power of its larger relatives". It can reach speeds of up to 50 km/h (31 mph) over short distances. However, it

6534-593: The highest levels of protection. "Sei whale" is an anglicization of the Norwegian seihval , meaning " pollock whale". The species was so called because it "appeared off the coast of Norway at the same time each year as the pollock that came to feed on the abundant plankton". In the Pacific, the whale has been called the Japan finner ; "finner" was a common term used to refer to rorquals. It has also been referred to as

6633-399: The human uterus is to prepare for the implantation of a zygote , a fertilized ovum , and maintenance of pregnancy if implantation occurs. Traveling along the fallopian tube on its way to the uterine cavity, the zygote divides mitotically to become a blastocyst , which ultimately attaches to the uterine wall and implants into the endometrium . The placenta later develops to nourish

6732-406: The human uterus lies in anteversion and anteflexion. In most women, the long axis of the uterus is bent forward on the long axis of the vagina, against the urinary bladder. This position is referred to as anteversion of the uterus. Furthermore, the long axis of the body of the uterus is bent forward at the level of the internal os with the long axis of the cervix. This position is termed anteflexion of

6831-403: The human, the lower end of the uterus is a narrow part known as the isthmus that connects to the cervix , the anterior gateway leading to the vagina . The upper end, the body of the uterus, is connected to the fallopian tubes at the uterine horns ; the rounded part, the fundus, is above the openings to the fallopian tubes. The connection of the uterine cavity with a fallopian tube is called

6930-446: The intestine, nematodes in the kidneys ( Crassicauda sp., California) and stomach ( Anisakis simplex , nearly 60% of whales taken off California), and flukes ( Lecithodesmus spinosus , found in 38% of individuals caught off California) in the liver. Mating occurs in temperate , subtropical seas during the winter. Gestation is estimated to vary around 10 3 ⁄ 4 months, 11 1 ⁄ 4 months, or one year. During

7029-413: The last resort: it is as of 2023, a relatively new and somewhat experimental procedure, performed only by certain specialist surgeons in select centres, it is expensive and unlikely to be covered by insurance, and it involves risk of infection and organ rejection. Some ethics specialists consider the risks to a live donor too great, and some find the entire procedure ethically questionable, especially since

7128-449: The late 1960s and early 1970s by Canadian whalers, and off the coast of West Greenland from the 1920s to the 1950s by Norwegian and Danish whalers. In the North Pacific, the total reported catch by commercial whalers was 72,215 between 1910 and 1975; the majority were taken after 1947. Shore stations in Japan and Korea processed 300–600 each year between 1911 and 1955. In 1959, the Japanese catch peaked at 1,340. Heavy exploitation in

7227-527: The late 19th and 20th centuries, when over 255,000 whales were killed, the sei whale is now internationally protected. It is listed as endangered by the IUCN Red List , despite increasing populations. The Northern Hemisphere population is listed under CITES Appendix II, which indicates they are not threatened with extinction , while the Southern Hemisphere population is listed under CITES Appendix I, indicating that they are threatened and are given

7326-662: The middle Miocene . Little is known about when members of the various families in the Mysticeti, including the Balaenopteridae, diverged from each other. Whole genome sequencing suggests that sei and blue whales are closely related, with gray whales as a sister group . This study also found significant gene flow between minke whales and the ancestors of the blue and sei whale. Two subspecies have been identified—the northern sei whale ( B. b. borealis ) and southern sei whale ( B. b. schlegelii ). The sei whale's body

7425-402: The most important role in its filter-feeding process. To feed, a baleen whale opens its mouth widely and scoops in dense shoals of prey (such as krill , copepods , small fish , and sometimes birds that happen to be near the shoals), together with large volumes of water. It then partly shuts its mouth and presses its tongue against its upper jaw, forcing the water to pass out sideways through

7524-536: The next. A 1985 study suggested a correlation between appearances west of Greenland and the incursion of relatively warm waters from the Irminger Current into that area. Some evidence from tagging data indicates individuals return off the coast of Iceland on an annual basis. An individual satellite-tagged off Faial , in the Azores , traveled more than 4,000 km (2,500 mi) to the Labrador Sea via

7623-677: The north coast of Java , Sibbaldius ( Balaenoptera ) schlegelii —in 1946 the Russian scientist A.G. Tomilin synonymized S. schlegelii and B. borealis , creating the subspecies B. b. schlegelii and B. b. borealis . In 1884–85, the Norwegian scientist G. A. Guldberg first identified the sejhval of Finnmark with B. borealis . Minke whale B. musculus ( blue whale ) B. borealis ( sei whale ) Eschrichtius robustus ( gray whale ) B. physalus ( fin whale ) Megaptera novaeangliae ( humpback whale ) Sei whales are rorquals (family Balaenopteridae), baleen whales that include

7722-495: The research is to examine what they eat and to assess the competition between whales and fisheries. In a span of 15 years, around 1,453 whales were killed in the North Pacific between 2002 and 2017. Conservation groups, such as the World Wildlife Fund , dispute the value of this research, claiming that sei whales feed primarily on squid and plankton which are not hunted by humans, and only rarely on fish . At

7821-523: The size of the whale's body. Adults have 300–380 ashy-black baleen plates on each side of the mouth, up to 80 cm (31 in) long. Each plate is made of fingernail-like keratin , which is bordered by a fringe of very fine, short, curly, wool-like white bristles. The sei's very fine baleen bristles, about 0.1 mm (0.0039 in), are the most reliable characteristic that distinguishes it from other rorquals. The sei whale looks very similar to other large rorquals, especially to its smaller relative

7920-602: The south coast of Newfoundland in August and September, and a southbound migration begins moving west and south along the Nova Scotian shelf from mid-September to mid-November. Whales in the Labrador Sea as early as the first week of June may move farther northward and arrive at waters southwest of Greenland later in the summer. In the northeast Atlantic, the sei whale winters as far south as West Africa such as off Bay of Arguin , off coastal Western Sahara and follows

8019-601: The species ended in 1977. Since the moratorium on commercial whaling, some sei whales have been taken by Icelandic and Japanese whalers under the IWC's scientific research programme. Iceland carried out four years of scientific whaling between 1986 and 1989, killing up to 40 sei whales a year. The research is conducted by the Institute of Cetacean Research (ICR) in Tokyo , a privately funded, nonprofit institution. The main focus of

8118-439: The term in utero . In humans, the uterus is located within the pelvic region immediately behind and almost overlying the bladder , and in front of the sigmoid colon . The human uterus is pear-shaped and about 7.6 cm (3.0 in) long, 4.5 cm (1.8 in) broad (side to side), and 3.0 cm (1.2 in) thick. A typical adult uterus weighs about 60 grams. The uterus can be divided anatomically into four regions:

8217-464: The transplant is not a life-saving procedure. Most animals that lay eggs , such as birds and reptiles , including most ovoviviparous species, have an oviduct instead of a uterus. However, recent research into the biology of the viviparous (not merely ovoviviparous ) skink Trachylepis ivensi has revealed development of a very close analogue to eutherian mammalian placental development. In monotremes , mammals which lay eggs, namely

8316-477: The triangle area around Kunashir Island in whaling days, making the area well known as sei – ground. There had been sightings of the species off the Sea of Japan during cetacean surveys. Sei whales have been recorded from northern Indian Ocean as well such as around Sri Lanka and Indian coasts. In the Southern Hemisphere, summer distribution based upon historic catch data is between 40°S and 50°S latitude in

8415-419: The uterus and form the uterine microbiome . The uterus is primarily supported by the pelvic diaphragm , perineal body , and urogenital diaphragm . Secondarily, it is supported by ligaments, including the peritoneal ligament and the broad ligament of uterus . The uterus is held in place by several peritoneal ligaments, of which the following are the most important (there are two of each): Normally,

8514-429: The uterus forms as a duplex organ of two uteri. In monotremes such as the platypus , the uterus is duplex and rather than nurturing the embryo, secretes the shell around the egg. It is essentially identical with the shell gland of birds and reptiles, with which the uterus is homologous . In mammals, the four main forms of the uterus are: duplex, bipartite, bicornuate and simplex. Two uteri usually form initially in

8613-492: The uterus from anastomosis of these two arteries. Afferent nerves supplying the uterus are T11 and T12 . Sympathetic supply is from the hypogastric plexus and the ovarian plexus . Parasympathetic supply is from the S2, S3 and S4 nerves. Bilateral Müllerian ducts form during early human fetal life. In males, anti-Müllerian hormone (AMH) secreted from the testes leads to the ducts' regression. In females, these ducts give rise to

8712-447: The uterus in anteflexion and anteversion (in 90% of women) and keeps it "floating" in the pelvis. The meanings of these terms are described below: The sustentacular part supports the pelvic organs and comprises the larger pelvic diaphragm in the back and the smaller urogenital diaphragm in the front. The pathological changes of the position of the uterus are: In cases where the uterus is "tipped", also known as retroverted uterus ,

8811-415: The uterus is known as Müllerian agenesis . A hysterectomy is the surgical removal of the uterus, which may be carried out for a number of reasons including the ridding of tumours both benign and malignant . A complete hysterectomy involves the removal of the body, fundus, and cervix of the uterus. A partial hysterectomy may just involve the removal of the uterine body while leaving the cervix intact. It

8910-413: The uterus. The uterus assumes an anteverted position in 50% of women, a retroverted position in 25% of women, and a midposed position in the remaining 25% of women. The uterus is located in the middle of the pelvic cavity, in the frontal plane (due to the broad ligament of the uterus ). The fundus does not extend above the linea terminalis , while the vaginal part of the cervix does not extend below

9009-455: The way the sandwiched tubular structures are packed together. Hydrated versus dry whale baleen also exhibit significantly different parallel and perpendicular compressive stress to compressive strain response. Although parallel loading for both hydrated and dry samples exhibit higher stress response (about 20 MPa and 140 MPa at 0.07 strain for hydrated and dry samples respectively) than that for perpendicular loading, hydration drastically reduced

9108-466: The whales prefer to stay inland here, even venturing into large bays. In general, the sei whale migrates annually from cool and subpolar waters in summer to temperate and subtropical waters for winter, where food is more abundant. In the northwest Atlantic, sightings and catch records suggest the whales move north along the shelf edge to arrive in the areas of Georges Bank , Northeast Channel , and Browns Bank by mid- to late- June. They are present off

9207-416: The woman may have symptoms of pain during sexual intercourse, pelvic pain during menstruation, minor incontinence, urinary tract infections, fertility difficulties, and difficulty using tampons. A pelvic examination by a doctor can determine if a uterus is tipped. The human uterus is supplied by arterial blood both from the uterine artery and the ovarian artery . Another anastomotic branch may also supply

9306-824: Was commonly used to crease paper; its flexibility kept it from damaging the paper. It was also occasionally used in cable-backed bows . Synthetic materials are now usually used for similar purposes, especially plastic and fiberglass . Baleen was also used by Dutch cabinetmakers for the production of pressed reliefs. In the United States, the Marine Mammal Protection Act in 1972 makes it illegal "for any person to transport, purchase, sell, export, or offer to purchase, sell, or export any marine mammal or marine mammal product". Sei whale The sei whale ( / s eɪ / SAY , Norwegian: [sæɪ] ; Balaenoptera borealis )

9405-855: Was found on 9% of individuals caught off California; it was also found on a sei whale taken off South Africa. The acorn barnacle Coronula reginae and the stalked barnacle Conchoderma virgatum were each only found on 0.4% of whales caught off California. Remora australis were rarely found on sei whales off California (only 0.8%). They often bear scars from the bites of cookiecutter sharks , with 100% of individuals sampled off California, South Africa, and South Georgia having them; these scars have also been found on sei whales captured off Finnmark. Diatom ( Cocconeis ceticola ) films on sei whales are rare, having been found on sei whales taken off California and South Georgia. Due to their diverse diet, endoparasites are frequent and abundant in sei whales. The harpacticoid copepod Balaenophilus unisetus infests

9504-627: Was lost between Madeira and the Canary Islands . The development of explosive harpoons and steam-powered whaling ships in the late nineteenth century brought previously unobtainable large whales within the reach of commercial whalers . Initially, the sei whale's speed and elusiveness partially protected them, and later the comparatively small yield of oil and meat . Once stocks of more profitable right whales , blue whales, fin whales, and humpback whales became depleted, sei whales were hunted in earnest, particularly from 1950 to 1980. In

9603-532: Was lost or that the traits for filter feeding originally evolved for other functions. It also shows that the evolution could have occurred gradually because the ancestral state was originally maintained. Therefore, the mosaic whales could have exploited new resources using filter feeding while not abandoning their previous prey strategies. The result of this stepwise transition is apparent in modern-day baleen whales, because of their enamel pseudogenes and their in utero development and reabsorbing of teeth. If it

9702-527: Was made in August 2004, compared to 19 sightings of Bryde's whales. Sei whales are commonly distributed along west to southern Latin America, including the entire Chilean coast down to the Beagle Channel . The Falkland Islands appear to be a regionally important area for the sei whale, as a small population exists in coastal waters off the eastern Falkland or Malvinas archipelago. For reasons unknown,

9801-510: Was really nice to do that. Everybody talked about it at the time I suppose, but it was money. At the end of the day that's what counted at the time. That's what we were there for." Sei whales live in all oceans, although rarely in polar or tropical waters. The difficulty of differentiating them at sea from their close relatives, Bryde's whales and in some cases from fin whales, creates confusion about their range and population, especially in warmer waters where Bryde's whales are most common. In

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