Search results
Results from the WOW.Com Content Network
Rodents make up the largest order of mammals, with over 40% of mammalian species. They have two incisors in the upper and lower jaw which grow continually and must be kept short by gnawing. Most rodents are small though the capybara can weigh up to 45 kg (99 lb).
All these introductions, perhaps except the fallow deer, have been "successful," resulting in viable populations. Sweden's Red List of critically endangered mammals includes Bechstein's bat, the common pipistrelle and the Arctic fox, while endangered mammals include the barbastelle, the serotine bat, the pond bat, the lesser noctule, and the wolf.
Mammals evolved on land, so all aquatic and semiaquatic mammals have brought many terrestrial adaptations into the waters. They do not breathe underwater as fish do, so their respiratory systems had to protect the body from the surrounding water; valvular nostrils and an intranarial larynx exclude water while breathing and swallowing.
Marine mammals were first hunted by aboriginal peoples for food and other resources. Many were also the target for commercial industry, leading to a sharp decline in all populations of exploited species, such as whales and seals. Commercial hunting led to the extinction of the Steller's sea cow, sea mink, Japanese sea lion and Caribbean monk seal.
The increased resistance to peripheral blood flow raises the blood pressure, which is compensated by bradycardia, conditions which are accentuated by cold water. [2] Aquatic mammals have blood volume that is some three times larger per mass than in humans, a difference augmented by considerably more oxygen bound to hemoglobin and myoglobin of ...
Aquatic animals generally conduct gas exchange in water by extracting dissolved oxygen via specialised respiratory organs called gills, through the skin or across enteral mucosae, although some are evolved from terrestrial ancestors that re-adapted to aquatic environments (e.g. marine reptiles and marine mammals), in which case they actually ...
Therefore, all amniote animals, even those that spend more time in water than out, are susceptible to drowning if they cannot reach the surface to breath. The anatomical structure of the lungs is less complex in reptiles than in mammals, with reptiles lacking the very extensive bronchial tree found in mammalian lungs.
The phlebotomic action opens a channel for contamination of the host species with bacteria, viruses and blood-borne parasites contained in the hematophagous organism. Thus, many animal and human infectious diseases are transmitted by hematophagous species, such as the bubonic plague, Chagas disease, dengue fever, eastern equine encephalitis, filariasis, leishmaniasis, Lyme disease, malaria ...