I discussed this in a lot more detail in my article on the pekapeka (a bat from New Zealand that spends about half its time on the ground), but in general, here are the reasons:
1. Compared to other flighted animal groups like birds and insects, bats are relatively new on the scene evolutionarily. They evolved flight about 52 million years ago. Compare that to birds, which have had about 150 million years to get comfortable with flying- only a few have ever lost it in that time.
2. Flying is a powerful antipredator defense and allows bats to get at resources they wouldn’t normally get, like flying insects and high-hanging flowers and fruit. This means there is currently strong evolutionary pressure for bats to retain flight in most parts of the world. One example where there was not was New Zealand (until recently). Even then, the pekapeka and its relatives retained the ability to fly.
3. Compared to birds, bats may simply be too specialized for flight to go back to being completely terrestrial. All living bats have modified hindlimbs and pelvises for flight, because their legs actually make up part of their wings.
It may be difficult to tell from that picture, but a bat’s hind legs are rotated at 90-180 degrees (depending on the species) around from where an ordinary mammal’s would be. In other words, their knees point backwards.
(This is different from a pterosaur, by the way- pterosaurs had wing membranes that attached to their hind limbs as well, but retained forward-pointing knees.)
This makes walking on the ground very difficult for them, and is related to why they roost upside-down. (In fact, some species of bats CAN’T walk on the ground at all!) Even when bats have regained the ability to be good walkers, like the vampire bat has, the style of locomotion is very different from all other living animals, like so:
It’s not a BAD way to get around, but energetically, it’s not as efficient as regular quadrupedal walking.
So, for a bat to “de-specialize” from flight completely might require extreme evolutionary pressures that don’t exist on earth right now. Not that I don’t think they could do it- but a flightless bat would end up looking really, really weird, compared to the mammals we’re used to.
I’m an old man living alone in an old house. My wife and I bought it
10 years ago, just before she passed. I don’t know how old it is. If I
had to guess, I’d say at least 150 years. It’s your typical old house
in back country southern United States, surrounded by forest and far
from the closest neighbor.
Simeis 147: Supernova Remnant : Its easy to get lost following the intricate strands of the Spaghetti Nebula. A supernova remnant cataloged as Simeis 147 and Sh2-240, the glowing gas filaments cover nearly 3 degrees 6 full moons on the sky. Thats about 150 light-years at the stellar debris clouds estimated distance of 3,000 light-years. This sharp composite includes image data taken through a narrow-band filter to highlight emission from hydrogen atoms tracing the shocked, glowing gas. The supernova remnant has an estimated age of about 40,000 years, meaning light from the massive stellar explosion first reached Earth about 40,000 years ago. But the expanding remnant is not the only aftermath. The cosmic catastrophe also left behind a spinning neutron star or pulsar, all that remains of the original stars core. via NASA
Early in the New Year, when most people are trying to stick to their resolutions, bakers are finalizing plans for gingerbread house contests nearly 12 months away. There are recipes to tinker with—a choice between “construction grade” gingerbread and the more delicious, softer variety—blueprints to create, and often hundreds of hours of work before houses are ready to be entered in a contest.
The National Gingerbread House Competition, one of the biggest gingerbread contests in the United States, takes place every year in Asheville, North Carolina. It started in 1992, when members of the local community were invited to display their gingerbread houses in The Omni Grove Park Inn’s great hall. Then someone had the idea to award a winner — and the contest has been growing ever since. People from the United States and Canada now submit roughly 150 entries per year.
Omega Centauri: The Brightest Globular Star Cluster : This huge ball of stars predates our Sun. Long before humankind evolved, before dinosaurs roamed, and even before our Earth existed, ancient globs of stars condensed and orbited a young Milky Way Galaxy. Of the 200 or so globular clusters that survive today, Omega Centauri is the largest, containing over ten million stars. Omega Centauri is also the brightest globular cluster, at apparent visual magnitude 3.9 it is visible to southern observers with the unaided eye. Cataloged as NGC 5139, Omega Centauri is about 18,000 light-years away and 150 light-years in diameter. Unlike many other globular clusters, the stars in Omega Centauri show several different ages and trace chemical abundances, indicating that the globular star cluster has a complex history over its 12 billion year age. via NASA
this looks like jackson is the chosen one to save the world and humanity and mark is the wise man who guides him through this battle and has 150 years old but stopped growing old by the age of 24 and now jackson is losing his faith and being insecure about the burden he has to carry and mark is trying to motivate him by being aggressive and putting even more pressure over him: “i… i cant do this” “there’s no ‘i cant do this’ jackson, dont you understand? the lives of these innocent people are in ur hands! dont let them down! dont let me down!”
M13: A Great Globular Cluster of Stars : M13 is one of the most prominent and best known globular clusters. Visible with binoculars in the constellation of Hercules, M13 is frequently one of the first objects found by curious sky gazers seeking celestials wonders beyond normal human vision. M13 is a colossal home to over 100,000 stars, spans over 150 light years across, lies over 20,000 light years distant, and is over 12 billion years old. At the 1974 dedication of Arecibo Observatory, a radio message about Earth was sent in the direction of M13. The featured image in HDR, taken through a small telescope, spans an angular size just larger than a full Moon, whereas the inset image, taken by Hubble Space Telescope, zooms in on the central 0.04 degrees. via NASA
There’s bound to be a lot of Star Wars posts today, but let me call your attention to another significant fact of May 4th. A careful reading of the text shows that Alice visited Wonderland on this day. And as the book was published in 1865, this would mark the 150th anniversary of a certain journey down the rabbit hole.