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A leopard seal (Hydrurga leptonyx) Marine mammals are mammals that rely on marine (saltwater) ecosystems for their existence. They include animals such as cetaceans (whales, dolphins and porpoises), pinnipeds (seals, sea lions and walruses), sirenians (manatees and dugongs), sea otters and polar bears. They are an informal group, unified only ...
The evolution of the digestive system has formed a significant influence in mammal evolution. With the emergence of mammals, the digestive system was modified in a variety of ways depending on the animal's diet. For example, cats and most carnivores have simple large intestines, while the horse as a herbivore has a voluminous large intestine. [127]
Marine biology is the scientific study of the biology of marine life, organisms that inhabit the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy.
The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. [ 2 ] Cetaceans are fully aquatic marine mammals belonging to the order Artiodactyla and branched off from other artiodactyls around ...
Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
Aquatic mammal. An Amazon river dolphin (Inia geoffrensis), a member of the infraorder Cetacea of the order Cetartiodactyla. Aquatic mammals and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of water. They include the various marine mammals who dwell in oceans, as well as various freshwater species ...
The Sirenia (/ saɪˈriːni.ə /), commonly referred to as sea cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct families: Dugongidae (the dugong and the now extinct Steller's sea cow) and Trichechidae ...
History of marine biology. Marine biology is a hybrid subject that combines aspects of organismal function, ecological interaction and the study of marine biodiversity. [1] The earliest studies of marine biology trace back to the Phoenicians and the Greeks who are known as the initial explorers of the oceans and their composition. [2]