'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
3
66489
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 7, 2013
2
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
16
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 7, 2020
4
2978
A black-coated Canada lynx was photographed for the first time by a researcher at the University of Alberta, Canada. Thomas Jung, also employed by the Government of Yukon, recorded the animal in a 30 second video on a cell ...
Plants & Animals
Oct 18, 2022
0
448
A fossilized lower jaw has led an international team of paleontologists, headed by Bastien Mennecart from the Natural History Museum Basel, to discover a new species of predator that once lived in Europe. These large predators ...
Paleontology & Fossils
Jun 15, 2022
0
737
Research led by a team of scientists from the Texas A&M School of Veterinary Medicine and Biomedical Sciences puts to bed the heated scientific debate regarding the history of mammal diversification as it relates to the extinction ...
Evolution
Apr 28, 2023
2
1746
A Cretaceous origin for placental mammals, the group that includes humans, dogs and bats, has been revealed by in-depth analysis of the fossil record, showing they co-existed with dinosaurs for a short time before the dinosaurs ...
Evolution
Jun 27, 2023
2
3120
Monash University scientists have challenged the conventional wisdom that biological patterns are explained by physical constraints.
Plants & Animals
Aug 19, 2022
7
3173
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