![]() ![]() To test this hypothesis, they made an expedition to the territory of one of the reserves of Botswana, where African elephants live, found several larger animals, and attached motion sensors and a GPS receiver to their neck and trunk.Ĭollecting these sensors in a few weeks, zoologists have uncovered many new and exciting facts about the life of elephants.įirst, it turned out that elephants can go most hours without sleep of all animals. On top of that, elephants seem only to dream once every 3-4 days.” It turned out that wild elephants sleep only two hours a day, which is a record low figure for mammals. Paul Manger of the Witwatersrand University in Johannesburg, South Africa, one of the scientists involved, said, “In captivity, elephants sleep about 4-6 hours, but we tracked their sleep in natural conditions. Based on a research study published in the journal PLOS One, these giant land mammals sleep just two hours a day, while their brains are not damaged or suffer from lack of sleep. Sleeping elephant cubs in the middle of adult elephants Scientific NameĮlephants are the most “sleepless” species of Animal Kingdom. Elephants- Biggest Animal that sleeps only 2 hours He also added that giraffes are generally very alert and use their height advantage to scan the horizon using their superior vision. ![]() “We found that key genes that regulate circadian rhythm and sleep were highly selected in giraffes, possibly allowing the giraffe to interrupt the sleep-wake cycle more often than other mammals,” said one of the study’s lead authors from the Department of Biology at the University of Copenhagen Rasmus Heller. The FGERL1 gene led to giraffes needing less sleep than other animals because it’s not easy for them to get up from sleep, let alone get up and run away from a predator. In 2021, a study led by an international team of researchers from the University of Copenhagen and Northwestern Polytechnic University in China found the genes responsible for this unique giraffe feature. Therefore, it also sleeps while standing with its eyes closed. The giraffe sometimes sticks its head between two branches that support it to avoid falling. They go to sleep very quickly – in 15-20 seconds.ĭuring the day, the giraffe is almost constantly in an upright position. Therefore, they also take a nap during the day to relax fully.Īt night, giraffes sleep lying down with their necks bent to rest their heads on the underside of their hind limbs. Since giraffes wake up very often at night, the duration of their deep sleep in total does not exceed 30 minutes. The mammalian sleep nature of giraffes has 10-50% REM sleep. On average, giraffes sleep 4.6 hours a day. Of all mammals, giraffes have one of the most negligible animal sleep requirements. Standing and sleeping giraffe Scientific Name Giraffe- Tallest Standing Sleeping Mammal The next day, the jellyfish activity, as expected, was reduced and recovered after they were allowed to sleep. Finally, the sleep-wake rhythms of jellyfish were altered by melatonin, as in humans and mammals.Īccording to Paul Sternberg, lead author of the study and a researcher at the California Institute of Technology, this new research pushes the study of the origin of sleep much further down the evolutionary tree of life – before a proper centralized nervous system appeared. The sleep researchers realized that the food that fell into the tanks could awaken the jellyfish through the following experiments with the addition of food.īiologists tried keeping jellyfish awake for 6 or 12 hours by spraying them with water. If the biologists raised jellyfish in an awake state, then they immediately sank to the bottom. Sleeping jellyfish in this situation, like only awakened people, reacted slowly. ![]() To ensure that this slowing down of the pulsation represented sleep, the scientists built a special elevator that lifted the jellyfish from the bottom, where they preferred to be, to the water’s surface. They found that at night the pulsation of the jellyfish dropped to 39 beats per minute and returned to 60 beats per minute during the day. The researchers manually counted individual impulses (heart rate) produced by contracted or relaxed phases at a constant rate and found that these impulses were less frequent during the night. The jellyfish in question, a stationary type Cassiopeia, which usually lives in mud and mangrove swamps, actually appeared to sleep during certain day phases. But research published in Current Biology in 2017 indicated that jellyfish also need sleep.Īnalysts from the California Institute of Technology in Pasadena observed 23 Cassiopeia jellyfish continuously for six nights and six days. For many, these sea creatures don’t show signs of sleep due to a lack of central nervous system or brain activity.
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