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82-521: The minke whale ( / ˈ m ɪ n k i / ), 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 naturalist Otto Fabricius in 1780, who assumed it must be an already known species and assigned his specimen to Balaena rostrata ,

164-528: A black/gray/purple color. Common minke whales (Northern Hemisphere variety) are distinguished from other whales by a white band on each flipper. The body is usually black or dark-gray above and white underneath. Minke whales have between 240 and 360 baleen plates on each side of their mouths. Most of the length of the back, including dorsal fin and blowholes, appears at once when the whale surfaces to breathe. Minke whales typically live between 30–50 years, but in some cases, they may live for up to 60 years. They have

246-559: A breast pump. During the latter part of pregnancy, the woman's breasts enter into the Secretory Differentiation stage. This is when the breasts make colostrum (see below), a thick, sometimes yellowish fluid. At this stage, high levels of progesterone inhibit most milk production. It is not a medical concern if a pregnant woman leaks any colostrum before her baby's birth, nor is it an indication of future milk production. At birth , prolactin levels remain high, while

328-469: A combination of those methods. Several protocols for inducing lactation were developed by Jack Newman and Lenore Goldfarb and are commonly called the Newman-Goldfarb protocols. The "regular protocol" involves the use of birth control pills to mimic the hormone levels of pregnancy with domperidone to stimulate milk production, followed by discontinuing the birth control and the introducing use of

410-403: A double electric breast pump to induce milk production. Additional protocols exist to support an accelerated timeline and to support induced lactation in menopausal parents. Some couples may stimulate lactation outside of pregnancy for sexual purposes . Rare accounts of male lactation (as distinct from galactorrhea ) exist in historical medical and anthropological literature. Most recently

492-401: A gestation and calving period of approximately 10–11 months and 2 years, respectively. Minke whales have a digestive system composed of four compartments with a high density of anaerobic bacteria throughout. The presence of the bacteria suggests minke whales rely on microbial digestion to extract nutrients provided by their food. As with most Mysticetes, the auditory system for the minke whale

574-530: A host in the case of symbionts or extreme environments). This may constrain possible directions of evolution; in such cases, strongly divergent selection is not to be expected. Also, asexual reproduction, such as through apomixis in plants, may separate lineages without producing a great degree of morphological differentiation. A species complex is usually a group that has one common ancestor (a monophyletic group), but closer examination can sometimes disprove that. For example, yellow-spotted "fire salamanders" in

656-413: A lactation is to provide nutrition and immune protection to the young after birth. Due to lactation, the mother-young pair can survive even if food is scarce or too hard for the young to attain, expanding the environmental conditions the species can withstand. The costly investment of energy and resources into milk is outweighed by the benefit to offspring survival. In almost all mammals, lactation induces

738-574: A long time period without evolving morphological differences. Hybrid speciation can be a component in the evolution of a species complex. Species complexes are ubiquitous and are identified by the rigorous study of differences between individual species that uses minute morphological details, tests of reproductive isolation , or DNA -based methods, such as molecular phylogenetics and DNA barcoding . The existence of extremely similar species may cause local and global species diversity to be underestimated. The recognition of similar-but-distinct species

820-750: A monitoring program. Scientists from James Cook University and the Museum of Tropical Queensland have worked closely with participating operators and the Authority, researching tourism impacts and implementing management protocols to ensure these interactions are ecologically sustainable. Minke whales are also occasionally sighted in Pacific waters, in and around the Haro Strait of British Columbia and Washington state . Species complex Two or more taxa that were once considered conspecific (of

902-459: A more attractive target of whalers. By 1979, the minke was the only whale caught by Southern Ocean fleets. Hunting continued apace until the general moratorium on whaling began in 1986. Following the moratorium, most hunting of minke whales ceased. Japan continued catching whales under the special research permit clause in the IWC convention, though in significantly smaller numbers. The stated purpose of

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984-459: A name given to the northern bottlenose whale by Otto Friedrich Müller in 1776. In 1804, Bernard Germain de Lacépède described a juvenile specimen of Balaenoptera acuto-rostrata . The name is a partial translation of Norwegian minkehval , possibly after a Norwegian whaler named Meincke, who mistook a northern minke whale for a blue whale . Most modern classifications split the minke whale into two species : Taxonomists further categorize

1066-482: A period of infertility (in humans, lactational amenorrhea ), which serves to provide the optimal birth spacing for survival of the offspring. From the eighteenth week of pregnancy (the second and third trimesters ), a woman's body produces hormones that stimulate the growth of the milk duct system in the breasts : It is also possible to induce lactation without pregnancy through combinations of birth control pills, galactagogues , and milk expression using

1148-573: A pronounced arching of the back. The maximum swimming speed of minkes has been estimated at 38 km/h (24 mph). Both species undertake seasonal migration routes to the poles during spring and towards the tropics during fall and winter. The difference between the timing of the seasons may prevent the two closely related species from mixing. A long-term photo identification study on the British Columbian and Washington coasts showed that some individuals travel as far as 424 km north in

1230-419: A slight tingling, others feel immense amounts of pressure or slight pain/discomfort, and still others do not feel anything different. A minority of mothers experience a dysphoric milk ejection reflex immediately before let-down, causing anxiety, anger or nausea, amongst other negative sensations, for up to a few minutes per feed. A poor milk ejection reflex can be due to sore or cracked nipples, separation from

1312-559: A species complex in formation. Nevertheless, similar but distinct species have sometimes been isolated for a long time without evolving differences, a phenomenon known as "morphological stasis". For example, the Amazonian frog Pristimantis ockendeni is actually at least three different species that diverged over 5 million years ago. Stabilizing selection has been invoked as a force maintaining similarity in species complexes, especially when they adapted to special environments (such as

1394-496: A species complex. Distinguishing close species within a complex requires the study of often very small differences. Morphological differences may be minute and visible only by the use of adapted methods, such as microscopy . However, distinct species sometimes have no morphological differences. In those cases, other characters, such as in the species' life history , behavior , physiology , and karyology , may be explored. For example, territorial songs are indicative of species in

1476-437: A species group usually have partially overlapping ranges but do not interbreed with one another. A Dictionary of Zoology ( Oxford University Press 1999) describes a species group as complex of related species that exist allopatrically and explains that the "grouping can often be supported by experimental crosses in which only certain pairs of species will produce hybrids ." The examples given below may support both uses of

1558-656: A subject of transgender health care , multiple case reports have described transgender women successfully inducing lactation. Research has indicated that such breast milk is nutritionally comparable to both the milk of naturally lactating and induced lactating cisgender women. Domperidone is a drug that can induce lactation. Charles Darwin recognized that mammary glands seemed to have developed specifically from cutaneous glands, and hypothesized that they evolved from glands in brood pouches of fish, where they would provide nourishment for eggs. The latter aspect of his hypothesis has not been confirmed; however, more recently

1640-477: Is called nursing , and in humans it is also called breastfeeding . Newborn infants often produce some milk from their own breast tissue, known colloquially as witch's milk . In most species, lactation is a sign that the female has been pregnant at some point in her life, although in humans and goats, it can happen without pregnancy. Nearly every species of mammal has teats ; except for monotremes , egg-laying mammals, which instead release milk through ducts in

1722-401: Is feeding from one breast. However, this and other problems often settle after two weeks of feeding. Stress or anxiety can cause difficulties with breastfeeding. The release of the hormone oxytocin leads to the milk ejection or let-down reflex . Oxytocin stimulates the muscles surrounding the breast to squeeze out the milk. Breastfeeding mothers describe the sensation differently. Some feel

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1804-431: Is important for disease and pest control and in conservation biology although the drawing of dividing lines between species can be inherently difficult . A species complex is typically considered as a group of close, but distinct species. Obviously, the concept is closely tied to the definition of a species. Modern biology understands a species as "separately evolving metapopulation lineage " but acknowledges that

1886-438: Is known for (biparentally) feeding their offspring by epidermal mucus secretion. A closer examination reveals that, as in mammals and birds, the secretion of this nourishing fluid may be controlled by prolactin. Similar behavior is seen in at least 30 species of cichlids . Lactation is also the hallmark of adenotrophic viviparity – a breeding mechanism developed by some insects, most notably tsetse flies . The single egg of

1968-623: Is not well understood. However, magnetic resonance imaging points to evidence that the minke whale has fat deposits in their jaws intended for sound reception, much like Odontocetes . The brains of minke whales have around 12.8 billion neocortical neurons and 98.2 billion neocortical glia . Additionally, despite its relatively large size, the minke whale is very fast, capable of swimming at speeds of 30 knots (35 mph), and their surfacing can be sporadic and hard to follow. The whale breathes three to five times at short intervals before "deep-diving" for 2 to 20 minutes. Deep dives are preceded by

2050-460: Is occurring, which leads to intermediate forms and blurred species boundaries. The informal classification, superspecies, can be exemplified by the grizzled skipper butterfly, which is a superspecies that is further divided into three subspecies. Some authors apply the term to a species with intraspecific variability , which might be a sign of ongoing or incipient speciation . Examples are ring species or species with subspecies , in which it

2132-504: Is often unclear if they should be considered separate species. Several terms are used synonymously for a species complex, but some of them may also have slightly different or narrower meanings. In the nomenclature codes of zoology and bacteriology, no taxonomic ranks are defined at the level between subgenus and species, but the botanical code defines four ranks below subgenus (section, subsection, series, and subseries). Different informal taxonomic solutions have been used to indicate

2214-518: Is one synonym for B. bonaerensis – B. huttoni (Gray 1874). Writing in his 1998 classification, Rice recognized two of the subspecies of the common minke whale – B. a. scammoni (Scammon's minke whale) and a further taxonomically unnamed subspecies found in the Southern Hemisphere, the dwarf minke whale (first described by Best as "Type 3," 1985). On at least one occasion, an Antarctic minke whale has been confirmed migrating to

2296-402: Is produced in the mother's oviduct epithelium 's hypertrophied glands, similar to mammal milk . The substance was released seemingly in response to tactile and acoustic stimulation by the babies. The researchers observed the hatchlings emitting high-pitched clicking sounds as they approached their mothers for milk, a behavior unique among amphibians. This milk-feeding behavior may contribute to

2378-790: The Arctic . In addition, at least two wild hybrids between a common minke whale and an Antarctic minke whale have been confirmed. The minke whales are the second smallest baleen whale; only the pygmy right whale is smaller. Upon reaching sexual maturity (7–8 years of age), males measure an average of 8.35 m (27.4 ft) and 7 t (6.9 long tons; 7.7 short tons) and females measure an average of 8.9 m (29 ft) and 8.25 t (8.12 long tons; 9.09 short tons) in length and body mass, respectively; estimated maximum size for females suggest that they can reach lengths exceeding 10 m (33 ft) and weigh more than 10–12 t (9.8–11.8 long tons; 11–13 short tons) in body mass. The minke whale has

2460-487: The Galápagos Islands described by Charles Darwin . It has been suggested that cryptic species complexes are very common in the marine environment. That suggestion came before the detailed analysis of many systems using DNA sequence data but has been proven to be correct. The increased use of DNA sequence in the investigation of organismal diversity (also called phylogeography and DNA barcoding ) has led to

2542-701: The IUCN Red List labels the common minke whale as Least Concern and the Antarctic minke whale as Near Threatened. COSEWIC puts both species in the Not At Risk category. NatureServe lists them as G5 which means the species is secure on global range. Population estimates are generated by the Scientific Committee of the International Whaling Commission . The 2004 estimate yielded 515,000 individuals for

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2624-626: The Isle of Mull in Scotland, County Cork in Ireland, and Húsavík in Iceland, and tours taken on the east coast of Canada. They are also one of the most commonly sighted whales seen on whale-watches from New England and eastern Canada. In contrast to humpback whales , minkes do not raise their flukes out of the water when diving and are less likely to breach (jump clear of the sea surface). In

2706-399: The criteria to delimit species may depend on the group studied. Thus, many traditionally defined species, based only on morphological similarity, have been found to be several distinct species when other criteria, such as genetic differentiation or reproductive isolation , are applied. A more restricted use applies the term to a group of species among which hybridisation has occurred or

2788-401: The hypothalamus , which signals to the posterior pituitary gland to produce oxytocin . Oxytocin stimulates contraction of the myoepithelial cells surrounding the alveoli, which already hold milk. The increased pressure causes milk to flow through the duct system and be released through the nipple. This response can be conditioned e.g. to the cry of the baby. Milk ejection is initiated in

2870-892: The malaria vector genus of mosquito, Anopheles , the fungi causing cryptococcosis , and sister species of Bactrocera tryoni , or the Queensland fruit fly. That pest is indistinguishable from two sister species except that B. tryoni inflicts widespread, devastating damage to Australian fruit crops, but the sister species do not. When a species is found to be several phylogenetically distinct species, each typically has smaller distribution ranges and population sizes than had been reckoned. The different species can also differ in their ecology, such as by having different breeding strategies or habitat requirements, which must be taken into account for appropriate management. For example, giraffe populations and subspecies differ genetically to such an extent that they may be considered species. Although

2952-510: The posterior pituitary , respectively. The oxytocin is produced in the neuron's soma in the supraoptic and paraventricular nuclei, and is then transported down the infundibulum via the hypothalamo-neurohypophyseal tract with the help of the carrier protein, neurophysin I , to the pars nervosa of the posterior pituitary, and then stored in Herring bodies , where they are stored until the synapse between second- and third-order neurons. Following

3034-471: The treecreepers , a bird genus with few morphological differences. Mating tests are common in some groups such as fungi to confirm the reproductive isolation of two species. Analysis of DNA sequences is becoming increasingly standard for species recognition and may, in many cases, be the only useful method. Different methods are used to analyse such genetic data, such as molecular phylogenetics or DNA barcoding . Such methods have greatly contributed to

3116-624: The "O stock" (Okhotsk sea, west Pacific). Seasonal variations in diet exist. J-stock whales' primary prey type is Japanese anchovy during May and June, Pacific saury in July and August, and krill in September. O-stock whales primarily feed on krill in July and August. Most minke whales observed in 2002 (90.4%) fed solely on one prey species. Antarctic minke whales are diurnal feeders. This minke whale population mainly feeds on Antarctic krill in offshore areas and ice krill in coastal areas on

3198-410: The Amazonian frog Eleutherodactylus ockendeni is actually at least three different species that diverged over 5 million years ago. A species flock may arise when a species penetrates a new geographical area and diversifies to occupy a variety of ecological niches , a process known as adaptive radiation . The first species flock to be recognized as such was the 13 species of Darwin's finches on

3280-465: The Antarctic minke stock. Whaling was mentioned in Norwegian written sources as early as the year 800, and hunting minke whales with harpoons was common in the 11th century. In the 19th century, they were considered too small to chase, and received their name from a young Norwegian whale-spotter in the crew of Svend Foyn , who harpooned one, mistaking it for a blue whale and was derided for it. By

3362-788: The North Atlantic, conception takes place from December to May with a peak month of February with birth taking place from October to March with a peak in December. In the North Pacific off Japan there appears to be two phases of conception, the majority of which occurs from February to March but also from August to September, with births occurring from December to January and June to July. In the Yellow Sea stock these two phases have not been noted with conception occurring from July to September and birth peaking from May to June. In

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3444-512: The Southern Hemisphere conception takes place from June to December with a peak in August and September. Peak birth time occurs from July to August. Killer whale predation on minke whales has been well documented. A study in 1975 found that in 49 killer whale stomachs, 84% had consumed minke whale. Minke whale carcasses investigated after attacks show that killer whales have an affinity for minke tongues and lower jaw. The anti-predatory mechanism of

3526-496: The abdomen. In only a handful of species of mammals, certain bat species, is milk production a normal male function . Galactopoiesis is the maintenance of milk production. This stage requires prolactin . Oxytocin is critical for the milk let-down reflex in response to suckling . Galactorrhea is milk production unrelated to nursing. It can occur in males and females of many mammal species as result of hormonal imbalances such as hyperprolactinaemia . The chief function of

3608-425: The breast") until 50–73 hours (2–3 days) after birth. Colostrum is the first milk a breastfed baby receives. It contains higher amounts of white blood cells and antibodies than mature milk, and is especially high in immunoglobulin A (IgA), which coats the lining of the baby's immature intestines, and helps to prevent pathogens from invading the baby's system. Secretory IgA also helps prevent food allergies. Over

3690-415: The breasts more fully also increases the rate of milk production. Thus the milk supply is strongly influenced by how often the baby feeds and how well it is able to transfer milk from the breast. Low supply can often be traced to: This is the mechanism by which milk is transported from the breast alveoli to the nipple . Suckling by the baby stimulates the paraventricular nuclei and supraoptic nucleus in

3772-616: The cells in the alveoli to make milk. Prolactin also transfers to the breast milk. Some research indicates that prolactin in milk is greater at times of higher milk production, and lower when breasts are fuller, and that the highest levels tend to occur between 2 a.m. and 6 a.m. Other hormones—notably insulin, thyroxine, and cortisol—are also involved, but their roles are not yet well understood. Although biochemical markers indicate that Secretory Activation begins about 30–40 hours after birth, mothers do not typically begin feeling increased breast fullness (the sensation of milk "coming in

3854-508: The common minke whale into two or three subspecies ; the North Atlantic minke whale, the North Pacific minke whale and dwarf minke whale. All minke whales are part of the rorquals , a family that includes the humpback whale , the fin whale , the Bryde's whale , the sei whale and the blue whale . The junior synonyms for B. acutorostrata are B. davidsoni (Scammon 1872), B. minimia (Rapp, 1837), and B. rostrata (Fabricius, 1780). There

3936-451: The continental shelf such as the Ross sea and Prydz bay. The population has been recorded to forage on ten known species: five fish ( Antarctic silverfish , Antarctic jonasfish , Antarctic lanternfish , Chionodraco , and Notothenia ), four euphausiids (Antarctic krill, ice krill, Euphausia frigida , Thysanoessa macrura ), and one amphipod ( Themisto gaudichaudii ). As of 2018,

4018-438: The delivery of the placenta results in a sudden drop in progesterone, estrogen, and HPL levels. This abrupt withdrawal of progesterone in the presence of high prolactin levels stimulates the copious milk production of Secretory Activation . When the breast is stimulated, prolactin levels in the blood rise, peak in about 45 minutes, and return to the pre-breastfeeding state about three hours later. The release of prolactin triggers

4100-533: The development of the hatchlings' microbiome and immune system, similar to mammalian young. The presence of milk production in caecilians that lay eggs suggests an evolutionary transition between egg-laying and live birth . Another well known example of nourishing young with secretions of glands is the crop milk of columbiform birds. As in mammals, this also appears to be directed by prolactin. Other birds such as flamingos and penguins utilize similar feeding techniques. The discus fish ( Symphysodon )

4182-407: The discovery of a great many cryptic species complexes in all habitats. In the marine bryozoan Celleporella hyalina , detailed morphological analyses and mating compatibility tests between the isolates identified by DNA sequence analysis were used to confirm that these groups consisted of more than 10 ecologically distinct species, which had been diverging for many millions of years. Evidence from

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4264-474: The discovery of cryptic species, including such emblematic species as the fly agaric , the water fleas , or the African elephants . Species forming a complex have typically diverged very recently from each other, which sometimes allows the retracing of the process of speciation . Species with differentiated populations, such as ring species , are sometimes seen as an example of early, ongoing speciation:

4346-413: The electrical impulse, oxytocin is released into the bloodstream. Through the bloodstream, oxytocin makes its way to myoepithelial cells , which lie between the extracellular matrix and luminal epithelial cells that also make up the alveoli in breast tissue. When oxytocin binds to the myoepithelial cells, the cells contract. The increased intra-alveolar pressure forces milk into the lactiferous sinuses, into

4428-475: The end of the 1930s, they were the target of coastal whaling by Brazil, Canada, China, Greenland, Japan, Korea, Norway, and South Africa. Minke whales were not then regularly hunted by the large-scale whaling operations in the Southern Ocean because of their relatively small size. However, by the early 1970s, following the overhunting of larger whales such as the sei , fin , and blue whales, minkes became

4510-464: The first two weeks after the birth, colostrum production slowly gives way to mature breast milk. The hormonal endocrine control system drives milk production during pregnancy and the first few days after the birth . When the milk supply is more firmly established, autocrine (or local) control system begins. During this stage, the more that milk is removed from the breasts, the more the breast will produce milk. Research also suggests that draining

4592-541: The genus Salamandra , formerly all classified as one species S. salamandra , are not monophyletic: the Corsican fire salamander 's closest relative has been shown to be the entirely black Alpine salamander . In such cases, similarity has arisen from convergent evolution . Hybrid speciation can lead to unclear species boundaries through a process of reticulate evolution , in which species have two parent species as their most recent common ancestors . In such cases,

4674-469: The giraffe, as a whole, is not considered to be threatened, if each cryptic species is considered separately, there is a much higher level of threat. Lactation Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals , although it may predate mammals. The process of feeding milk in all female creatures

4756-539: The hybrid species may have intermediate characters, such as in Heliconius butterflies. Hybrid speciation has been observed in various species complexes, such as insects, fungi, and plants. In plants, hybridization often takes place through polyploidization , and hybrid plant species are called nothospecies . Sources differ on whether or not members of a species group share a range . A source from Iowa State University Department of Agronomy states that members of

4838-424: The identification of cryptic species has led some to conclude that current estimates of global species richness are too low. Pests, species that cause diseases and their vectors, have direct importance for humans. When they are found to be cryptic species complexes, the ecology and the virulence of each of these species need to be re-evaluated to devise appropriate control strategies. Examples are cryptic species in

4920-411: The infant, a history of breast surgery , or tissue damage from prior breast trauma . If a mother has trouble breastfeeding, different methods of assisting the milk ejection reflex may help. These include feeding in a familiar and comfortable location, massage of the breast or back, or warming the breast with a cloth or shower. This is the mechanism by which milk is transported from the breast alveoli to

5002-400: The journal Science , has shed light on the behavior of certain species of caecilians . These studies reveal that some caecilians exhibit a phenomenon wherein they provide their hatchlings with a nutrient-rich substance akin to milk, delivered through a maternal vent. Among the species investigated, the oviparous nonmammalian caecilian amphibian Siphonops annulatus stood out, indicating that

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5084-636: The lactiferous ducts (a study found that lactiferous sinuses may not exist. If this is true then milk simply enters the lactiferous ducts), and then out the nipple. A surge of oxytocin also causes the uterus to contract. During breastfeeding, mothers may feel these contractions as afterpains . These may range from period-like cramps to strong labour-like contractions and can be more severe with second and subsequent babies. In humans, induced lactation and relactation have been observed frequently in some cultures, and demonstrated with varying success in adoptive mothers and wet nurses . It appears plausible that

5166-446: The mineralized eggs produced by some sauropsids. This protolacteal fluid became a complex, nutrient-rich milk which then allowed a decline in egg size by reducing the dependence on a large yolk in the egg. The evolution of lactation is also believed to have resulted in the more complex dentition seen in mammals, as lactation would have allowed the prolonged development of the jaw before the eruption of teeth. Oftedal also proposed that

5248-420: The minke whale is strictly a flight response, as when this fails no physical retaliation is observed. Chases most commonly lead into open ocean, although there have been records of minke whales inadvertently swimming into confined, shallow waters. There have been two recorded instances of minke whales ending high speed chases by hiding under a ship's hull; however, both instances were unsuccessful. Minke whales in

5330-638: The moratorium, they had placed an objection to it with the IWC and resumed a commercial hunt of the Common minke whale in 1993. The quota for 2006 was set at 1,052 animals, but only 546 were taken. The quota for 2011 was set at 1286. In August 2003, Iceland announced it would start research catches to estimate whether the stocks around the island could sustain hunting. Three years later, in 2006, Iceland resumed commercial whaling. A 2007 analysis of DNA fingerprinting of whale meat estimated South Korean fishermen caught 827 minke between 1999 and 2003, approximately twice

5412-503: The most commonly observed prey species, followed by herring and sprat. Seasonal variations are observed off Finnmark , with krill the most popular prey type in the summer and cod in the autumn. Stable isotope analysis from 2003 shows minke whales in the north Atlantic also feed on prey from lower trophic levels. Two stocks of minke whale are observed in the North Pacific : the "J stock" (Sea of Japan, Yellow Sea, East China sea) and

5494-417: The mother's breast by the act of suckling by the baby. The milk ejection reflex (also called let-down reflex) is not always consistent, especially at first. Once a woman is conditioned to nursing, let-down can be triggered by a variety of stimuli, including the sound of any baby. Even thinking about breastfeeding can stimulate this reflex, causing unwanted leakage, or both breasts may give out milk when an infant

5576-430: The nipple. Suckling by the baby innervates slowly adapting and rapidly-adapting mechanoreceptors that are densely packed around the areolar region. The electrical impulse follows the spinothalamic tract , which begins by innervation of fourth intercostal nerves . The electrical impulse then ascends the posterolateral tract for one or two vertebral levels and synapses with second-order neurons, called tract cells, in

5658-476: The north Atlantic are observed to take a variety of food items. Before 1993, minke whales in the north Barents Sea fed predominantly on capelin until stocks collapsed and the whales switched to krill as their primary prey type. The minke whale population in the Norwegian Sea primarily feeds on adult herring while krill, capelin, and sand eels are also recorded prey types. In Scotland, sand eels are

5740-655: The northern Great Barrier Reef (Australia), a swim-with-whales tourism industry has developed based on the June and July migration of dwarf minke whales. A limited number of reef tourism operators (based in Port Douglas and Cairns ) have been granted permits by the Great Barrier Reef Marine Park Authority to conduct these swims, given strict adherence to a code of practice, and that operators report details of all sightings as part of

5822-404: The officially reported number. This raised concerns that some whales were being caught deliberately. In July 2019, Japan resumed commercial whaling activities. The permitted catch for the initial season (July 1 – December 31, 2019) is 227 whales, of which 52 can be minke. Due to their relative abundance, minke whales are often the focus of whale-watching cruises setting sail from, for instance,

5904-424: The possibility of lactation in women (or females of other species) who are not biological mothers does confer an evolutionary advantage, especially in groups with high maternal mortality and tight social bonds. The phenomenon has been also observed in most primates, in some lemurs, and in dwarf mongooses. Lactation can be induced in humans by a combination of physical and psychological stimulation, by drugs, or by

5986-422: The posterior dorsal horn. The tract cells then decussate via the anterior white commissure to the anterolateral corner and ascend to the supraoptic nucleus and paraventricular nucleus in the hypothalamus , where they synapse with oxytocinergic third-order neurons. The somas of these neurons are located in the hypothalamus, but their axon and axon terminals are located in the infundibulum and pars nervosa of

6068-632: The practice of lactation may be more widespread among these creatures than previously thought. As detailed in a 2024 study, researchers collected 16 mothers of the Siphonops annulatus species from cacao plantations in Brazil's Atlantic Forest and filmed them with their altricial hatchlings in the lab. The mothers remained with their offspring, which suckled on a white, viscous liquid from their cloaca , experiencing rapid growth in their first week. This milk-like substance, rich in fats and carbohydrates ,

6150-563: The protolacteal fluid was initially secreted through pilosebaceous glands on mammary patches, analogous to the areola, and that hairs on this patch transported the fluid to the hatchlings as is seen in monotremes . This would have occurred in the mammal lineages that diverged after monotremes, metatheria and eutheria . In this scenario, some genes and signaling pathways involved in lactation evolved from ancient precursors which facilitated secretions from spiny structures, which themselves evolved from odontodes . Recent research, as documented in

6232-467: The research is to establish data to support a case for the resumption of sustainable commercial whaling. Environmental organizations and several governments contend that research whaling is simply a cover for commercial whaling. The 2006 catch by Japanese whalers included 505 Antarctic minke whales. Between November 2017 and March 2018, Japan reported catches of a total of 333 Minke whales, of which 122 were pregnant females. Although Norway initially followed

6314-550: The same mechanism has been postulated for early synapsids . As all mammals lactate, lactation must have evolved before the last common ancestor of all mammals, which places it at a minimum in the Middle or Late Triassic when monotremes diverged from therians. O. T. Oftedal has argued that therapsids evolved a proto-lacteal fluid in order to keep eggs moist, an adaptation necessitated due to synapsids’ parchment shelled eggs which are more vulnerable to evaporation and dehydration than

6396-417: The same species) may later be subdivided into infraspecific taxa (taxa within a species, such as bacterial strains or plant varieties ), which may be a complex ranking but it is not a species complex. In most cases, a species complex is a monophyletic group of species with a common ancestor, but there are exceptions. It may represent an early stage after speciation in which the species were separated for

6478-461: The same species. Where closely related species co-exist in sympatry , it is often a particular challenge to understand how the similar species persist without outcompeting each other. Niche partitioning is one mechanism invoked to explain that. Indeed, studies in some species complexes suggest that species divergence have gone in par with ecological differentiation, with species now preferring different microhabitats. Similar methods also found that

6560-453: The spring, and 398 km south to warmer waters in the autumn. Many specifics about migration in this species still remain unclear. The gestation period for minke whales is ten months, and calves measure 2.4 to 2.8 m (7.9 to 9.2 ft) at birth. The newborns nurse for five to ten months. Breeding peaks during the summer months. Calving is thought to occur every two years. The timing of conception and birth varies between region. In

6642-561: The term "species group." Often, such complexes do not become evident until a new species is introduced into the system, which breaks down existing species barriers. An example is the introduction of the Spanish slug in Northern Europe , where interbreeding with the local black slug and red slug , which were traditionally considered clearly separate species that did not interbreed, shows that they may be actually just subspecies of

6724-516: The tsetse develops into a larva inside the uterus where it is fed by a milky substance secreted by a milk gland inside the uterus. The cockroach species Diploptera punctata is also known to feed their offspring by milky secretions. Toxeus magnus , an ant-mimicking jumping spider species of Southeast Asia, also lactates. It nurses its offspring for about 38 days, although they are able to forage on their own after 21 days. Blocking nursing immediately after birth resulted in complete mortality of

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