'Sushi parasites' have increased 283-fold in past 40 years
The next time you eat sashimi, nigiri or other forms of raw fish, consider doing a quick check for worms.
The next time you eat sashimi, nigiri or other forms of raw fish, consider doing a quick check for worms.
Ecology
Mar 19, 2020
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Imagine if you only had one shot at passing on your genes before you died. It happens more often in the natural world than you might expect: suicidal reproduction – where one or both sexes of a species die after a single ...
Plants & Animals
Oct 07, 2013
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0
Humans are exterminating animal and plant species so quickly that nature's built-in defence mechanism, evolution, cannot keep up. An Aarhus-led research team calculated that if current conservation efforts are not improved, ...
Evolution
Oct 15, 2018
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14557
Deprived of oxygen, naked mole-rats can survive by metabolizing fructose just as plants do, researchers report this week in the journal Science.
Plants & Animals
Apr 20, 2017
2
9617
The first-ever detailed study of the diets of great white sharks off the east Australian coast reveals this apex predator spends more time feeding close to the seabed than expected.
Plants & Animals
Jun 07, 2020
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2978
Researchers recently made a major discovery—14 new species of shrews, which is the largest number of new mammals described in a scientific paper since 1931. After a decade-long journey taking inventory of Indonesian shrews ...
Plants & Animals
Dec 15, 2021
1
568
Where is the world's greatest concentration of unique species of mammals? A team of American and Filipino authors have concluded that it is Luzon Island, in the Philippines. Their 15-year project, summarized in a paper published ...
Plants & Animals
Jul 14, 2016
2
8579
The most detailed study to date of ancient predators trapped in the La Brea Tar Pits is helping Americans understand why today we're dealing with coyotes dumping over garbage cans and not saber-toothed cats ripping our arms ...
Archaeology
Aug 05, 2019
0
2064
Scientists at the University of Liverpool have shed new light on how diving mammals, such as the sperm whale, have evolved to survive for long periods underwater without breathing.
Plants & Animals
Jun 13, 2013
0
0
A new study led by researchers from the Oxford University Museum of Natural History, University of Oxford and the University of Birmingham for Current Biology has used new methods to analyze the variability of mammal fossils, ...
Paleontology & Fossils
May 17, 2021
0
3153
Mammals (formally Mammalia) are a class of vertebrate animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair, three middle ear bones used in hearing, and a neocortex region in the brain.
Mammals are divided into three main categories depending how they are born. These categories are, monotremes, marsupials and placentals. Except for the five species of monotremes (which lay eggs), all mammal species give birth to live young. Most mammals also possess specialized teeth, and the largest group of mammals, the placentals, use a placenta during gestation. The mammalian brain regulates endothermic and circulatory systems, including a four-chambered heart.
There are approximately 5,400 species of mammals, distributed in about 1,200 genera, 153 families, and 29 orders (though this varies by classification scheme). Mammals range in size from the 30–40-millimetre (1.2–1.6 in) Bumblebee Bat to the 33-metre (110 ft) Blue Whale.
Mammals are divided into two subclasses, the prototheria, which includes the oviparous monotremes, and the theria, which includes the placentals and live-bearing marsupials. Most mammals, including the six largest orders, belong to the placental group. The three largest orders, in descending order, are Rodentia (mice, rats, and other small, gnawing mammals), Chiroptera (bats), and Soricomorpha (shrews, moles and solenodons). The next three largest orders include the Carnivora (dogs, cats, weasels, bears, seals, and their relatives), the Cetartiodactyla (including the even-toed hoofed mammals and the whales) and the Primates to which the human species belongs. The relative size of these latter three orders differs according to the classification scheme and definitions used by various authors.
Phylogenetically, Mammalia is defined as all descendants of the most recent common ancestor of monotremes (e.g., echidnas and platypuses) and therian mammals (marsupials and placentals). This means that some extinct groups of "mammals" are not members of the crown group Mammalia, even though most of them have all the characteristics that traditionally would have classified them as mammals. These "mammals" are now usually placed in the unranked clade Mammaliaformes.
The mammalian line of descent diverged from an amniote line at the end of the Carboniferous period. One line of amniotes would lead to reptiles, while the other would lead to synapsids, including mammals. The first true mammals appeared in the Triassic period. Modern mammalian orders appeared in the Palaeocene and Eocene epochs of the Palaeogene period.
This text uses material from Wikipedia, licensed under CC BY-SA