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Bacteria also live in symbiotic and parasitic relationships with plants and animals. Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbour membrane-bound organelles.
External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. [1] It is contrasted with internal fertilization, in which sperm are introduced via insemination and then combine with an egg inside the body of a female organism.
The omasum's main function is to absorb water and nutrients from the digestible feed. The abomasum has a similar function to the human stomach. [14] Cattle regurgitate and re-chew their food in the process of chewing the cud, like most ruminants. While feeding, cows swallow their food without chewing; it goes into the rumen for storage.
The hydrothermal vent microbial community includes all unicellular organisms that live and reproduce in a chemically distinct area around hydrothermal vents. These include organisms in the microbial mat, free floating cells, or bacteria in an endosymbiotic relationship with animals. Chemolithoautotrophic bacteria derive nutrients and energy ...
Manatees (/ ˈ m æ n ə t iː z /, family Trichechidae, genus Trichechus) are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows.There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia: the Amazonian manatee (Trichechus inunguis), the West Indian manatee (Trichechus manatus), and the West ...
Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime.
The recently extinct Steller's sea cow was the largest known sirenian to have lived, reaching lengths of 10 metres (33 feet) and weights of 5 to 10 tonnes (5.5 to 11.0 short tons). [2] Sirenians have a large, fusiform body which reduces drag through the water and heavy bones that act as ballast to counteract the buoyancy of their blubber. They ...
A water buffalo chewing cud. The alimentary canal of ruminants, such as cattle, giraffes, goats, sheep, alpacas, and antelope, are unable to produce the enzymes required to break down the cellulose and hemicellulose of plant matter. [2]