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Whale Channel
Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and porpoises. Dolphins and porpoises may be considered whales from a formal, cladistic perspective. Whales, dolphins and porpoises belong to the order Cetartiodactyla, which consists of even-toed ungulates. Their closest non-cetacean living relatives are the hippopotamuses, from which they and other cetaceans diverged about 54 million years ago. The two parvorders of whales, baleen whales (Mysticeti) and toothed whales (Odontoceti), are thought to have had their last common ancestor around 34 million years ago. Mysticetes include four extant (living) families: Balaenopteridae (the rorquals), Balaenidae (right whales), Cetotheriidae (the pygmy right whale), and Eschrichtiidae (the grey whale). Odontocetes include the Monodontidae (belugas and narw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', 'Eos, Dawn') and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.See: *Letter from William Whewell to Charles Lyell dated 31 January 1831 in: * From p. 55: "The period next antecedent we shall call Eocene, from ήως, aurora, and χαινος, recens, because the extremely small proportion of living species contained in these strata, indicates what may be considered the first commencement, or ''dawn'', of the existing state of the animate creation." The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isoto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porpoise
Porpoises () are small Oceanic dolphin, dolphin-like cetaceans classified under the family Phocoenidae. Although similar in appearance to dolphins, they are more closely related to narwhals and Beluga whale, belugas than to the Oceanic dolphin, true dolphins. There are eight extant species of porpoise, all among the smallest of the toothed whales. Porpoises are distinguished from dolphins by their flattened, spade-shaped teeth distinct from the conical teeth of dolphins, and lack of a pronounced beak, although some dolphins (e.g. Hector's dolphin) also lack a pronounced beak. Porpoises, and other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates. Porpoises range in size from the vaquita, at in length and in weight, to the Dall's porpoise, at and . Several species exhibit sexual dimorphism in that the females are larger than males. They have streamlined bodies and two limbs that are modified into flippers. Porpoises use Animal echolocation, echolocatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetotheriidae
Cetotheriidae is a family of baleen whales (parvorder Mysticeti). The family is known to have existed from the Late Oligocene to the Early Pleistocene before going extinct. Although some phylogenetic studies conducted by recovered the living pygmy right whale as a member of Cetotheriidae, making the pygmy right whale the only living cetotheriid, other authors either dispute this placement or recover Neobalaenidae as a sister group to Cetotheriidae. Taxonomy After its description by Brant in 1872, Cetotheriidae was used as a wastebasket taxon for baleen whales which were not assignable to extant whale families. Comparing the cranial and mandibular morphology of 23 taxa (including late archaeocetes and both fossil and extant mysticetes), found Cetotheriidae in this traditional sense to be polyphyletic. Based on ten cranial characters, they also concluded that of the twelve included fossil baleen-bearing mysticetes, six formed a monophyletic group, Cetotheriidae ''sensu stricto' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balaenidae
Balaenidae () is a Family (biology), family of whales of the parvorder Mysticeti (baleen whales) that contains mostly fossil taxa and two living genera: the right whale (genus ''Eubalaena''), and the closely related bowhead whale (genus ''Balaena''). Taxonomy *Family Balaenidae **Genus ''Balaena'' ***Bowhead whale, ''Balaena mysticetus'' **Genus ''Eubalaena'' ***North Atlantic right whale, ''Eubalaena glacialis'' ***North Pacific right whale, ''Eubalaena japonica'' ***Southern right whale, ''Eubalaena australis'' Until recently, all right whales of the genus ''Eubalaena'' were considered a single species—''E. glacialis''. In 2000, genetic studies of right whales from the different ocean basins led scientists to conclude that the populations in the North Atlantic, North Pacific and Southern Hemisphere constitute three distinct species. Further genetic analysis in 2005 using mitochondrial DNA and nuclear DNA has supported the conclusion that the three populations should be tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balaenopteridae
Rorquals () are the largest clade, group of baleen whales, comprising the family (biology), family Balaenopteridae, which contains nine extant taxon, extant species in two genus, genera. They include the largest known animal that has ever lived, the blue whale, which can reach , and the fin whale, which reaches ; even the smallest of the group, the northern minke whale, reaches . Rorquals take their name from French language, French , which derives from the Norwegian language, Norwegian word : the first element originated from the Old Norse 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, ''Balaenoptera''. 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 and common minke whale, which have shorter grooves). These furro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family (, : ) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". The delineation of what constitutes a family—or whether a described family should be acknowledged—is established and decided upon by active taxonomists. There are not strict regulations for outlining or acknowledging a family, yet in the realm of plants, these classifications often rely on both the vegetative and reproductive characteristics of plant species. Taxonomists frequently hold varying perspectives on these descriptions, leading to a lack of widespread consensus within the scientific community ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neontology
Neontology is a part of biology that, in contrast to paleontology, studies and deals with living (or, more generally, '' recent'') organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with members still alive, as opposed to (all) being extinct. For example: * The Indian elephant (''Elephas maximus'') is an extant species, and the woolly mammoth (''Mammuthus primigenius'') is an extinct species. * The moose (''Alces alces'') is an extant species, and the Irish elk (''Megaloceros giganteus'') is an extinct species. * In the group of molluscs known as the cephalopods, there were approximately 600 extant species and 7,500 extinct species. A taxon can be classified as extinct if it is broadly agreed or certified that no members of the group are still alive. Conversely, an extinct taxon can be reclassified as extant if there are new discoveries of living species (" Lazarus species"), or if previously known extant species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Most Recent Common Ancestor
A most recent common ancestor (MRCA), also known as a last common ancestor (LCA), is the most recent individual from which all organisms of a set are inferred to have descended. The most recent common ancestor of a higher taxon is generally assumed to have been a species. The term is also used in reference to the ancestry of groups of genes (haplotypes) rather than organisms. The ancestry of a set of individuals can sometimes be determined by referring to an established pedigree, although this may refer only to patrilineal or matrilineal lines for sexually-reproducing organisms with two parents, four grandparents, etc. However, in general, it is impossible to identify the exact MRCA of a large set of individuals, but an estimate of the time at which the MRCA lived can often be given. Such ''time to most recent common ancestor'' (''TMRCA'') estimates can be given based on DNA test results and established mutation rates as practiced in genetic genealogy, or by reference to a non- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toothed Whale
The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales with teeth, such as beaked whales and the sperm whales. 73 species of toothed whales are described. They are one of two living groups of cetaceans, the other being the baleen whales (Mysticeti), which have baleen instead of teeth. The two groups are thought to have diverged around 34 million years ago (mya). Toothed whales range in size from the and vaquita to the and sperm whale. Several species of odontocetes exhibit sexual dimorphism, in that there are size or other morphological differences between females and males. They have streamlined bodies and two limbs that are modified into flippers. Some can travel at up to 30 knots. Odontocetes have conical teeth designed for catching fish or squid. They have well-developed hearing that is well adapted for both air and water, so much so that some can survive even i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 plankton from the water. Mysticeti comprises the family (biology), families Balaenidae (right whale, right and Bowhead whale, bowhead whales), Balaenopteridae (rorquals), Eschrichtiidae (the gray whale) and Cetotheriidae (the pygmy right whale). There are currently 16 species of baleen whales. While cetaceans were historically thought to have descended from Mesonychia, mesonychians, molecular phylogenetics, molecular evidence instead supports them as a clade of even-toed ungulates (Artiodactyla). Baleen whales split from toothed whales (Odontoceti) around 34 mya (unit), million years ago. Baleen whales range in size from the and pygmy right whale to the and blue whale, the Largest organisms, largest known animal to have ever existed. They ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parvorder
Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. An immediately higher rank, superorder, is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families. What does and does not belong to each order is determined by a taxonomist, as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with a capital letter. For some groups of organisms, their orders may follow consisten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hippopotamus
The hippopotamus (''Hippopotamus amphibius;'' ; : hippopotamuses), often shortened to hippo (: hippos), further qualified as the common hippopotamus, Nile hippopotamus and river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extant species in the family Hippopotamidae, the other being the pygmy hippopotamus (''Choeropsis liberiensis'' or ''Hexaprotodon liberiensis''). Its name comes from the ancient Greek for "river horse" (). After elephants and rhinoceroses, the hippopotamus is the next largest land mammal. It is also the largest extant land artiodactyl. Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, the closest living relatives of the hippopotamids are cetaceans (whales, dolphins, porpoises, etc.), from which they diverged about 55 million years ago. Hippos are recognisable for their barrel-shaped torsos, wide-opening mouths with large canine tusks, nearly hairless bodies, pillar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
