Are Bats Rodents?

Are Bats Rodents?

Bats are not rodents.  Both are mammals, but the bat belongs to the order Chiroptera while all rodents belong to the order Rodentia.  The two orders together represent 60% of all mammals.

What Makes a Bat a Bat?

All bats belong to the order Chiroptera.  The order is further broken down into two sub-orders, including 18 families and more than 1200 species.  Representing 20% of all mammal species, the order Chiroptera is second in number only to the order Rodentia. 

Up until 1778, bats were classified as primates until Johann Friedrich Blumenbach recognized their unique characteristics and gave them their own order, Chiroptera.  Today’s system for classification is based on the bat’s bone structure proposed by Miller in 1907.

With so many species of bats, the variations between them are extensive, but there are several features that distinguish them from other mammals and place them in the Chiroptera taxonomic classification.

• The Chiroptera order includes the only mammals with the ability to fly.
• All bats have elongated finger bones with pectoral specialization to support them.
• All bats have claws on the thumb.
• All bats have a reduced ulna bone in the forearm.
• All bats have knees that point rearward and outward.
• Some bat species are unique in that they use echolocation to navigate at night.

What Makes a Rodent a Rodent?

All rodents belong to the order Rodentia.  This order is so extensive it is further broken down into 29 families, 468 genera, and more than 2052 species.  It is no surprise that rodents represent 40% of all mammal species.

Two separate systems are used to classify rodents.  The first, created by J.F. Brandt in 1855, is based on the relationship between the jaw, skull, and jaw muscle.  The second is based on the position of the incisors (front teeth) and the jaw angle.  With so many species of rodents, the variations between them are vast, but there are similarities that unify them.

The Rodent Dentition Is the Unifying Characteristic

The main physical characteristic that makes a rodent unique is its teeth.  The dentition of rodents varies slightly based on dietary needs, but in general, rodents have two pairs of incisors, no canines, one to two pre-molars, and up to twelve molars.

• Rodents have two pairs of rootless incisors (front teeth), one on the upper and one on the lower, growing continuously throughout their lives.
• Incisors are sharpened for gnawing every time they rub together because they only have enamel on the front surface.
• Rodents also have upper and lower molars that are positioned far from the incisors, causing a space between the incisors.
• The jaw is perfectly shaped to ensure that the incisors do not meet while food is chewed and molars do not meet when the animal is gnawing with the incisors.

Additional unifying characteristics of rodents include:

• Rodents lack sweat glands.
• Males have accessory sex glands and a penile bone.

Resources

Britannica.com
“Bat Classification – Distinguishing Taxonomic Features”
https://www.britannica.com/animal/bat-mammal/Classification

Neuweiler, Gerhard (2000). “Phylogeny and systematics”. The Biology of Bats. Oxford University Press. pp. 287–299

Delaney, Martha A., Treuting, Piper M., Rothenburger, Jamie L., “Pathology of Wildlife and Zoo Animals”, Academic Press 2018 pp: 499-513
https://www.sciencedirect.com/science/article/pii/B9780128053065000201

Britannica.com
“Rodents”
https://www.britannica.com/animal/rodent