Total oxygen deprivation can be fatal to any animal even in a matter of minutes. Sometimes the body responds to this total lack of oxygen in a very unique way. Certain animals such as the seal can remain under water for more than 20 minutes and certain species of whales can even stay longer for over an hour. How are these animals able to achieve this feat?
By recording the heart beat and blood pressure of a variety of diving animals, it has been discovered that soon after the dive commences the cardiac frequency decreases dramatically(bradycardia) and the arterioles of organs constrict (except the vital organs). The rapid reflex response results in the body’s oxygen store, derived from its haemoglobin and myoglobin, being sent to those organs that are least able to endure sudden or total oxygen deprivation such as the heart and the brain.
This response is not just restricted to diving animals such as seals and whales but it has been shown that several other animals are confronted with sudden or total oxygen deprivation. An example here is man. A diver will develop bradycardia within 30 seconds after the beginning of a dive while fishes experience bradycardia when taken out of water.
Total oxygen deprivation is a serious medical condition where the blood cannot get enough oxygen to meet the body’s demands. This can be caused by severe bronchial asthma or asphyxiation from smoke inhalation, carbon monoxide poisoning, suicide attempts, cardiac arrests, anesthesia accidents, heart attacks, or a variety of other conditions. If untreated, oxygen deprivation can cause coma or death.
Humans can go months without food and several days without water, but only minutes without oxygen before brain damage sets in. The degree of damage depends on how long the person goes without oxygen and can include changes in personality or behavior, memory loss, hallucinations, and muscle weakness. Some people who are seriously oxygen-deprived recover with no ill effects, while others stay in a vegetative state and have little hope of recovery.
Animals respond to hypoxia by slowing breathing, heartbeat and blood circulation, reducing energy use and limiting blood flow through the lungs. These adaptations can help animals survive in environments with limited oxygen, such as subterranean burrow systems, high altitudes, and deep ocean habitats.
It was previously thought that all multicellular organisms require oxygen for life, but in 2010 researchers discovered three species of multicellular animals that can survive completely without oxygen by randomly switching to a metabolic pathway that doesn’t need oxygen and produces ethanol as a byproduct. The lollipop-shaped creature called Henneguya salminicola lacks mitochondria, the subcellular structures that turn oxygen into chemical energy for all cellular functions.