Could Bats Ever Learn How To Hover?

[common_sense_seeker]

Or is there a major problem with their body plan and wing structure which would likely prevent this ability from evolving? Any experts here?

 

[phlogistician]

Are you incapable of using Google?

 

[common_sense_seeker]

Are you incapable of using Google?

This time I forgot. Air Bubbles Keep Bats Afloat. So they can, but is there a limit on the maximum size where there energy saving vortex technique will cease to be effective? Can (hypothetical) bats bigger than flying foxes ever learn to hover with ease? Could a hovering 'robo-bat' be built to any size in theory? “Robo bats” with metal muscles may herald next gen of flying machines.

 

[Enmos]

This time I forgot. Air Bubbles Keep Bats Afloat. So they can, but is there a limit on the maximum size where there energy saving vortex technique will cease to be effective? Can (hypothetical) bats bigger than flying foxes ever learn to hover with ease? Could a hovering 'robo-bat' be built to any size in theory? “Robo bats” with metal muscles may herald next gen of flying machines.

Can Blue Whales ever learn to hover with ease? That is what I want to know.

What the hell is the purpose of these questions??

 

[spidergoat]

Why would you think bats cannot hover?

 

[common_sense_seeker]

Why would you think bats cannot hover?

They don't appear to be as good at hovering as birds, but I could be wrong. It's the cryptozoological connection I'm interested in i.e. large scary unknown creatures that fly at night.

 

[Fraggle Rocker]

. . . . is there a limit on the maximum size where there energy saving vortex technique will cease to be effective?

Lift is proportional to the surface area of the wing, a two-dimensional measure. Mass is proportional to the volume of the animal, a three-dimensional measure. So as the linear dimension of an animal increases, the rate of increase of the mass is proportional to the 3/2 power of the rate of increase of the wing area. This means the wings must be proportionally larger for a larger animal. Compare a hummingbird's wings, which are smaller than its body, to a macaw's wings, which eclipse its body when unfurled, to a condor's wings, which comprise most of its silhouette in flight.

For a 300-lb ostrich to fly it would need something like a hundred-foot wingspan. And the breastbone necessary to anchor those muscles would be too large and awkward for it to survive, even if it evolved a clever way to fold up its wings when on the ground.

So yes, there is a maximum size for any animal when you're calculating its power of flight. IIRC the largest bird that can barely fly at all weighs around forty pounds.

 

[Orleander]

Are you incapable of using Google?

...

...What the hell is the purpose of these questions??[/QUOTE]

what's wrong with asking? :shrug:

 

[common_sense_seeker]

Lift is proportional to the surface area of the wing, a two-dimensional measure. Mass is proportional to the volume of the animal, a three-dimensional measure. So as the linear dimension of an animal increases, the rate of increase of the mass is proportional to the 3/2 power of the rate of increase of the wing area. This means the wings must be proportionally larger for a larger animal. Compare a hummingbird's wings, which are smaller than its body, to a macaw's wings, which eclipse its body when unfurled, to a condor's wings, which comprise most of its silhouette in flight.

For a 300-lb ostrich to fly it would need something like a hundred-foot wingspan. And the breastbone necessary to anchor those muscles would be too large and awkward for it to survive, even if it evolved a clever way to fold up its wings when on the ground.

So yes, there is a maximum size for any animal when you're calculating its power of flight. IIRC the largest bird that can barely fly at all weighs around forty pounds.

How do you account for the 60feet wingspan of the biggest pterosaur? Is it the same rules? Discover magazine

 

[Fraggle Rocker]

How do you account for the 60feet wingspan of the biggest pterosaur? Is it the same rules?

The article notes that the creature was better able to glide than to fly, and that it had to jump to even get off the ground. This is similar to the forty-pound bird--a species of bustard, IIRC.

Many of the largest birds today are raptors, who spend a lot of time riding thermals waiting for food to appear. Flying requires too much energy.

 

[common_sense_seeker]

The article notes that the creature was better able to glide than to fly, and that it had to jump to even get off the ground. This is similar to the forty-pound bird--a species of bustard, IIRC.

Many of the largest birds today are raptors, who spend a lot of time riding thermals waiting for food to appear. Flying requires too much energy.

You're talking about flying by the flapping of wing appendages. What if a creature that had evolved to 'fly' through the ocean, both forwards and backwards, similar to the action of a squid, then became adapted to aerial flight through the evolution of gliding above the waves? In this scenario, a 'manta-ray-flier' would be able to fly with much greater efficiency than the land-to-air evolved birds and bats.

 

[Fraggle Rocker]

You're talking about flying by the flapping of wing appendages. What if a creature that had evolved to 'fly' through the ocean, both forwards and backwards, similar to the action of a squid, then became adapted to aerial flight through the evolution of gliding above the waves? In this scenario, a 'manta-ray-flier' would be able to fly with much greater efficiency than the land-to-air evolved birds and bats.

The motions of flight are modestly effective in water, and indeed a few marine birds use their wings as well as their feet for swimming. But the motions of swimming are not effective for flight. Water is buoyant so an animal needs to generate little or no lift in order to move through it, merely propulsion. And water is viscous so fins are very useful for steering.

Much of the energy used for flying goes into generating lift by flapping the wings in a manner that marine creatures don't have the musculature for. It takes huge muscles and a prominent breastbone to anchor them, or some equivalently strong infrastructure. And steering in flight requires asymmetrical flapping of the wings, not the adjustment of a directional fin.

And don't forget the rule of the square-to-cube ratio; that's basic physics and no animal is exempt from it. The mass of an animal increases as the cube of its linear dimension, whereas the lift its wing can generate increases only as the square, so a larger animal must have disproportionately larger wings.

The motions that mantas and other sea creatures use for locomotion in a thick medium like water would be virtually useless in a thin medium like air.

The "flying fish" is actually a glider like the "flying squirrel," incapable of generating lift and gaining altitude. And it can't go very far before landing back in the water.

 

[kurros]

You could have some kind of helium balloon manta ray, that could be fun . It'd get blown around a lot though.

 

[ElectricFetus]

There are bats that drink nectar, I would assume they must hover to suck out a flower.

so questioned answered: bats can hover. End of thread.

 

[ElectricFetus]

For a 300-lb ostrich to fly it would need something like a hundred-foot wingspan. And the breastbone necessary to anchor those muscles would be too large and awkward for it to survive, even if it evolved a clever way to fold up its wings when on the ground.

So Quetzalcoatlus must have had those wings for something other than flight back then?

 

[Enmos]

Adding to Electrics post:

Hovering Bats Stay Aloft Using Swirling Vortices
Spedding said. “We have suspected for a while that insects weren’t the only creatures
affected by highly unsteady viscous air flows, but now we know that larger animals
adapted for slow and hovering flight, such as these nectar-feeding bats, can – and
perhaps must – use LEVs to enhance flight performance.

Simplified representation of the strong vortices associated with the unsteady
aerodynamics of bat flight at slow speeds. The vortices can be thought of as
causing the surrounding air to rotate rapidly around them, and this motion
around the LEV on top of the wing increases the lift force on it. Just like familiar,
fixed-wing planes, the bat also leaves tip vortices in its wake, but the overall
flow is further modified by the start vortices created at the
beginning of the downstroke.
(Credit: Image courtesy of University of Southern California)
The article: http://www.sciencedaily.com/releases/2008/02/080229135215.htm​

Another article: How Do Bats Hover? Just like insects.

 

[common_sense_seeker]

So Quetzalcoatlus must have had those wings for something other than flight back then?

Good point. Maybe there were more thermals back then with stronger winds in general?

Much of the energy used for flying goes into generating lift by flapping the wings in a manner that marine creatures don't have the musculature for. It takes huge muscles and a prominent breastbone to anchor them, or some equivalently strong infrastructure.

And don't forget the rule of the square-to-cube ratio; that's basic physics and no animal is exempt from it. The mass of an animal increases as the cube of its linear dimension, whereas the lift its wing can generate increases only as the square, so a larger animal must have disproportionately larger wings.

The motions that mantas and other sea creatures use for locomotion in a thick medium like water would be virtually useless in a thin medium like air.

In the case of the rays, it has recently been discovered that cartilage is a lot stronger than previously thought (Science Illustarted Sep/Oct). The cownose ray has a specialised ligament which increases the effectiveness of it's boneless bite, so that it can crush the hard shells of crustaceans. Therefore your generalisations are just that and shouldn't be taken so literally. The fact remains that it IS conceivable that a ray did evolve to attain true flight capability. Jaws of Death - cartilaginous fishes - Brief Article

If you were an oyster, the last thing you'd want is a ray with a crush on you.

Sharks, rays, and ratfishes share a special burden: these cartilaginous fishes are saddled with a reputation for being somehow inferior to vertebrates blessed with bony skeletons.

Bone is certainly a wonderfully strong material. It lets hyenas crush carcasses with their jaws and enables elephants to support their massive bodies. Bone tissue is crammed with cells known as osteocytes and blood vessels that keep them nourished. The osteocytes release calcium, phosphates, and other minerals, which help make bones strong. They form layers that wrap around the outside of the bone and create a dense web of branching columns inside it.

The cartilage in sharks and rays, by comparison, consists primarily of a mesh of collagen fibers embedded in a gelatin-like matrix, along with a scattering of cartilage-generating cells called chondrocytes. (Sometimes the cartilage is surrounded by a thin layer of mineralized tissue that gives it a little extra stiffness.) The result is a softness and flexibility that imply a certain weakness. After all, it is backbone we admire in a person, not cartilage.

Dating back at least 420 million years, cartilaginous fishes are sometimes referred to as primitive--as if cartilage were an intermediate step on the climb from invertebrates to bony vertebrates. The development of a human embryo seems to replay this imagined evolutionary ascent: the embryo starts out with a skeleton of pure cartilage that gradually turns almost completely to bone. As adults, we retain only a few vestiges of cartilage--in the nose, the ear, the voice box, the disks between the vertebrae, and at the ends of free-moving bones.

Adam Summers, a biologist at the University of California, Berkeley, is determined to show that this supposed inferiority of cartilaginous fishes is a biomechanical myth. Cartilage is indeed generally weaker than bone but at times can become remarkably stiff and strong. For the past few years, Summers has been studying the cownose ray (Rhinoptera bonasus). This three-foot-wide creature, which lives solely on hard-shelled mollusks, is a scourge of oystermen; a school of 3,000 rays can pick an oyster bed clean in an afternoon. A ray eats its prey by grabbing the mollusk in its mouth and crushing the shell with its jaws.

 

[Enmos]

So Quetzalcoatlus must have had those wings for something other than flight back then?

Quetzalcoatlus was build for flight, Ostriches are not. They were much lighter per unit of volume than Ostriches.

 

[Enmos]

Good point. Maybe there were more thermals back then with stronger winds in general?

"Presumably Quetzalcoatlus could take off under its own power, but once aloft it may have spent much of its time soaring."

"Mass estimates for giant azhdarchids are extremely problematic because no existing species share a similar size or body plan, and as a result published results vary widely. A 2002 study suggested a body mass of 90–120 kilograms (200–260 lb) for Quetzalcoatlus, considerably lower than most other recent estimates. Higher estimates tend toward 200–250 kilograms (440–550 lb)."

http://en.wikipedia.org/wiki/Quetzalcoatlus

 

[Idle Mind]

In the case of the rays, it has recently been discovered that cartilage is a lot stronger than previously thought (Science Illustarted Sep/Oct). The cownose ray has a specialised ligament which increases the effectiveness of it's boneless bite, so that it can crush the hard shells of crustaceans. Therefore your generalisations are just that and shouldn't be taken so literally. The fact remains that it IS conceivable that a ray did evolve to attain true flight capability.

So, wait. Let me get this straight. You are referencing an article that talks about the bite strength of a particular species of ray to support the idea that rays are able to fly in air? Can you not see what is wrong with this?