Bats are mammals in all ramifications, but with the added advantage that they can fly. They are, in fact, the only mammals that can sustain flight for long–although the flying squirrel can move through the air, but as it spans short distances, it is considered only as gliding.
What makes bats the special mammals that fly? Do bats have hollow bones like their other flying neighbors, the birds?
No, bats do not have hollow bones, but instead, they have flat bones as all mammals do. Birds are the only class of animals that can fly. For flying to be a possibility, birds have hollow bones in which they store oxygen for extended flight. As Bats do not have hollow bones, what other mechanisms and structures do they have that make flying possible?
How Do Bats Fly If They Have No Hollow bones?
The absence of hollow bones isn’t that big a minus. Bats being the wonderful creatures they are have developed in every way that was lacking to cover up for the big gap.
As the hollow bones in birds serve as a reservoir for oxygen, and the feathers on the wings of birds serve as instruments of flight, in what areas has the bat made up for the absence of these two important pieces to aid?
Related Article: Are Bats Considered Marsupials?
The membranes that serve as wings
As we have mentioned several times, birds have hollow bones. The hollow bone in birds is basically where respiration takes place.
Their lungs are placed throughout the empty space in the hole, and the oxygen that comes through here is absorbed into the blood, which gives birds that extra internal push during flight.
But bats do not have hollow bones… they have an even better mechanism.
Instead of one extended arm covered in feathers, as is the case in birds, bats have a thin membrane supported by extended phalanges. And because the membrane has a larger surface area, the exchange of air is made easier and quicker, making up for the absence of hollow bones.
Increased metabolic rates
Before being flying animals, bats are omnivore mammals first. And as omnivores, the consumption of large amounts of food is a must to stay alive.
However, a large amount of food stored in the body contributes to weight, and more weight added can create an imbalance that will hinder flight.
So in preparation for the flight, bats increase metabolic rates to digest food as quickly as they are eaten to reduce additional weight. According to research, bats excretes about 30 minutes to 1 hour after a meal.
To make up for the non-present bones that propel flight, bats have flat bones. The bones of bats are relatively small and light in weight compared to those of other mammals.
Being a mammal with a handful of digestive organs, having these lightly structured bones has gone a long way to reduce the relative weight of the bats.
As stated above, bats are not birds. Bats are only flying mammals, and they belong to the class Mammalia, while birds belong to the class Aves.
Animals in the class, Aves, have many attributes different from those in the class Mammalia, and one of these features is the presence of hollow bones and feathers. The wings of the birds are covered with feathers that are instrumental in their flight.
Bats do not have true wings because they do not have feathers. In the place of feathers, bats developed extended phalanges that provide support for the thin membranes that serve as wings for flight.
These phalanges are the same as fingers in humans. They are more flexible. And because of this, the movements of bats are more fluid and flexible compared to the birds!
Related: Is Bat a Bird?
Do Bats Have Backbones?
Just like all mammals, bats have backbones as well. The backbone is made up of bones, tendons, muscles, and nerves, and it protects the spinal cord and supports the weight of an animal.
Having a backbone is the main physical part that separates vertebrates from invertebrates animals. And bats, by belonging to the group of vertebrates animal species, have a spine.
Besides the backbone, bats have:
- 7 neck (cervical) bones
- 4 abdominal (lumbar) bones
- 11 chest (thoracic) bones
Are There Any Mammals With Hollow Bones?
No, there are no mammals that have hollow bones. Mammals have dense bones, filled with a soft, fatty tissue called marrow.
Marrow plays a significant role when it comes to mammal’s health. The bone marrow’s key role lies in the production of different blood cells that are crucial for every mammal’s life.
Hollow bones are particularly the physical characteristics of birds. In addition to having different bones, birds and mammals actually have very different skeletal structures.
Birds have evolved into animals that primarily fly or swim. On the other side, mammals have more kinds of locomotions, such as walking, climbing, burrowing, jumping, galloping, swimming.
As a result, these two groups of animals belong to different classifications, and they differ in many physical characteristics, not only by bone density.
People often confuse bats with birds, hence the thought of them having hollow bones. Bats are mammals, and unlike birds, they have no hollow bones. Bat bones are denser but small and lightweight compared to other mammals.
Light bones combined with a thin membrane supported by extended phalanges make the bats the only mammals that are able to fly.