It’s a Bird! It’s a Plane! It’s a…Mobula Ray?

Flying Mobula Ray

When it comes to the world of the great blue sea, people generally don’t tend to think of things flying through the air.  Sure, sometimes someone will bring up flying fish.  Penguins also may come to mind, but they are just birds who can’t fly.  Out there though there are much, much weirder members of the aquatic life community. One of those weird creatures is the Mobula Ray.  Sometimes mistaken for a manta ray, the mobula ray, a relative of the manta, is found in tropical waters all over the world, but is most famously known existing in the Sea of Cortez off the coast of Mexico. More commonly the mobula ray is called a devil ray or an eagle ray.

No one is quite sure why the mobulas do this. There are many, many explanations from scientists, including mobula experts, all over the world. Even experts say that their own theories are just as reasonable as the next guys and there are no explanations with any more proof than others. Everything from removing parasites clinging to their bodies, to exercise, to a mating process, to hunting, to simply play have been discussed as reasons for the creatures breaching the surface in the way that they do.

In general, very little is known about the mobula rays. There are a number of different species within the Mobula genus. They can span about 12 feet from wing tip to wing tip and weigh over a ton when fully grown. Their schools can be made up of hundreds of individual rays that cover ocean floors with their expanse of black bodies. They are affected by large industrial fishing, getting caught in the nets of fishing companies and others which have depleted their numbers. They are also caught by fishermen of the coast of Mexico who then can prepare and sell their meat for profit.

The numbers of the mobula rays, who lack any defense except their size and speed, has been dwindling in recent years and leads many to worry about their survival in the Sea of Cortez and elsewhere.

Works Cited:

  • Wikipedia Article: Wiki
  • Picture: Picture Source
  • “Mobula Ray Pictures Reveal Spectacular Leaps”: Article
  • “The Flying Mobulas of the Sea Of Cortez”: Article

Why Can the Peregrine Falcon Fly So Fast?

The peregrine falcon is the fastest animal on earth. When not hunting, this bird generally flies between 40 and 60 mph. However, when diving to catch its prey, the peregrine falcon can reach speeds of up to 220 mph. What allows it to reach such high speeds when other birds cannot? The peregrine falcon has many features that set it apart from other birds, making it one of the deadliest predators out there. These features are its keel, pointed wings, stiff feathers, and incredibly efficient respiratory and circulatory systems.

peregrine_falcon

A bird’s keel is a bone specialized for flight, a modified breastbone. A birds muscles for flapping are attached to its keel. The peregrine falcon has a very large keel, allowing more muscle to be attached to it and in turn more flapping power to be generated.

peregrine_falcon_streamlined

The peregrine falcon’s pointed wings also help the bird reach its mind-boggling speeds. The wings are swept back and contributed to the bird’s streamlined figure. “The curved wings create an air foil effect in multiple dimensions, maximizing maneuverability, lift, and speed” (Harker Bio).

peregrine_falcon_feathers

The feathers of the peregrine falcon also contribute to its high speeds. The feathers are slim and stiff, reducing the drag that can be caused by loose limp feathers.

The peregrine falcon appears extremely aerodynamic, but if it were not for its incredibly efficient respiratory and circulatory systems, it would not be able to reach the speeds it does. The peregrine falcon can breathe effortlessly at speeds of over 200 mph while “Other birds can’t even breathe when flying at speeds half as fast” (Horton). The peregrine falcon can do this because it has a one-way air flow into its lungs. The peregrine falcon has air sacs that keep its lungs inflated even when exhaling. The peregrine falcon also has a very strong heart that beats between 600 and 900 times per minute, allowing the oxygen to travel throughout the bird at high rates so it does not fatigue quickly. The amazing speed of its heartbeat allows the peregrine falcon to flap its wings up to four times per second, contributing to its speed.

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Leading Edge Vortices In Bats

Leading-edge vortex on a bat's wing

Using Digital Particle Image Velocimetry, scientists are able to show the velocity of the airflow surrounding the wing of the bat. This demonstrates the leading edge vortices that occur on the surface of a bat wing.

Bats are different than insects and birds in the way that they fly. They are different because instead of rigid wings like insects, or stiff wings like birds, they have a very flexible wing due to a membrane that covers over two-dozen independent joins. Because of this membrane the bats are able to have more maneuverability and fly using less energy. But even with this advantage flying at slow speeds and hovering is very difficult. Insects use several different techniques to hover and to do this they mostly use leading edge vortices. But for the longest time, these leading edge vortices were thought only to apply to insects. In recent years, however, studies have shown that the reason bats can hover and fly so slowly is due to these leading edge vortices.

What are leading edge vortices? And how do they form? These two questions go hand in hand. When a bat completes its down stroke, the sharp leading edge cuts through the air that flows over the length of the wing, then comes back and “reattaches” itself to the wing.  It forms a vortex, where instead of the air just flowing over the wing it comes back, creating a circulating movement of air over the wing. This generates lift, and then on the upstroke a lot of this lift is conserved because the upstroke sheds the vortex, and since the bat brings its wings close to its body, does not generate a lot of drag. This makes the down stroke more efficient because less of the aerodynamic forces generated are lost. These vortices generate a significant part the lift needed to sustain the flight of the bat when it is hovering and or flying at slow speeds.

These vortices, in slow and hovering flight, account for a good portion of the aerodynamic forces to sustain the flight of a bat. Some scientists have even shown that up to forty percent of the lift in slow and or hovering flight is generated by these leading edge vortices. If that amount of force can be generated from these vortices hopefully scientists can work with engineers to use this information and apply it to new technologies. Especially when it comes to the maneuverability and the hovering capabilities found in animals that have these leading edge vortices. Some are trying to build micro air vehicles with these capabilities, but maybe one day we will all by hovering and flying with the help of these leading edge vortices.

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Archaeopteryx: The World’s First Bird (Probably)

 

Archaeopteryx represents a pivotal moment in the evolution of birds, which have come to inhabit every corner of the earth.  This is a species which conveys the transitional period from therapod dinosaurs to early birds.  Archaeopteryx fully maintains many of the characteristics of its running dinosaur relatives, such as sharp teeth and a long bony tail, while simultaneously introducing numerous features common to nearly all birds today.   Although Archaeopteryx gives us  a snapshot of the divergence of birds from dinosaurs, it manages to raise nearly as many questions about the evolution of avian flight as it answers. 

One issue with the dinosaur origins of birds has been brain size and function.  The fossil record suggests that dinosaurs had particularly small brains compared to their body size.  In fact, the film Jurassic Park was really the first time anyone portrayed dinosaurs as cunning or clever.  This posed an issue for flight, because flight requires heightened motor control and other higher order neurological processes, which terrestrial based life does not have to perform.  To adress this issue, in 2004, Dominguez Alonso used CT scans from the brain casings of various Archaeopteryx to model its brain.  Alonso’s results suggest that Archaeopteryx had a far larger brain than most dinosaurs, making its brain comprable to pterasaurs.  The models indicate that about 33% of the brain was dedicated to sight, and the areas responsible for muscular coordination and hearing were also well developed.   All these data would seem to suggest that archaeopteryx would have the neurological capacity for flight.

For a number of years, Archaeopteryx had lent little to no conclusive evidence to crediting either the terrestrial or arboreal origins of flight.  Evolutionary biologists have been split for decades about whether ther first flighers had a running start from the ground or some help from gravity by gliding from trees.   In 2010 Robert Nudds and Gareth Dyke of the University of Manchester published their results on the possible aerodynamics of Archaeopteryx.  The analysis of the imprints of feathers from the fossil record seems to indicate that Archaeopteryx must not have been a very good flapping flyer.  They had a significantly different feather structure than modern birds.  Nudds and Dyke conclude that the only way Archaeopteryx could have flapped its wings would be if the rachises of their winds were solid rather than holllow, like every other flying bird on the face of the earth today.   This seems to indicate that flight originated from the trees down and that flapping flight origninated in some divergent branch of the evolutionary tree of Archaeopteryx.

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Flying Squid

When one thinks of animals that are capable of flight, birds, various insects, flying  squirrels, bats, and certain snakes, fish, and lizards might come to mind. Well, you can add another animal to that list. In 2001, marine biologist Silvia Macia was boating off the coast of Jamaica when she witnessed a squid launch out of the water and seemingly fly through the air before diving back down below the surface. That’s right, flying squid. This sighting prompted prompted Macia and her colleagues to investigate further into squid flight.

These squid have been seen to fly distances up to 10 meters and heights of 3 meters above the surface. While 10 meters distance may not seem that large, you must take into account that these squid are a mere 20 centimeters on average. So flying ten meters is flying 50 times there body length. That’s like me taking off and flying the length of a football field.

flying-squid

Source: see below.

While the complete mechanics of squid flight are yet to be confirmed, the main source of thrust is jet propulsion. Jet propulsion is the expelling of a jet of liquid or gas, in this case ocean water, in the opposite direction of motion. Thus by the law of conservation of momentum, the squid is then propelled forward.

The more peculiar aspect of their flight is the use of their fins and tentacles. When soaring through the air they appear to flap their fins and spiral their tails. While it is yet to be confirmed, many suspect that the fins are acting as wings, aiding to the lift generation. Scientists are now analyzing photos of the squids in flight, hoping to calculate their velocity as well as other details.

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