We always love it when our followers are enthusiastic to learn more about the world around them! The content below is a transcription of questions received on social media that needed a better platform for response. We will likely continue to post social media questions to our blog in the future, so that we can encourage question submissions and make sure we give you a complete responses that can be searchable and reference-able going forward.
Questions submitted by Instagram user thecrasiansoo in response to a photo of a Texas shrew species.
Q: What is a shrew?
Shrews are a family of mammals, more closely related to moles and despite common misconception, NOT part of the rodent family. The Etruscan shrew is the smallest terrestrial mammal in the world, and the shrew family is 4th most diverse, exceeded only by two rodent families and the family of bats known as Vespers. Shrews are mainly insectivorous, eating small bugs in grass and leaf litter, as well as burrowing for worms. However, some shrew species climb trees or even hunt in water! Another cool fact is that moles and shrews genuinely do have poor eyesight and rely heavily on other senses, mainly smell...unlike bats who, despite popular belief, actually have great vision and use echolocation as a supplemental navigational tool.
Q:So then, are rodents not mammals? I didn't know that! (I kind of wish moles were mammals so you could call them "mamMOLES"...)
Oh no, all of those types of animals are mammals. So you CAN say "maMOLES" to be funny! :)
Scientific classification, starting from largest category working down to smallest specific categories, goes:
I choose to remember this with the acronym KPCOFGS, but some people use mnemonic devices. The internet tells me a popular one is "King Phillip Came Over For Good Spaghetti."
So for the animals you inquired about, this would be:
Kingdom - Animalia
(Animalia means multi-cellular, eukaryotic organisms)
Phylum - Chordata
(Chordata means having a flexible spinal column. Vertebrata is a sub-phylum of Chordata, which indicates animals with a vertebrate backbone structure, includes most animals you can think of ranging from fish, birds, reptiles, amphibians, mammals. The only animals that fall under Chordata but not the sub-phylum Vertebrata are things like lancelets and sea squirts. The Classes under this Phylum include: Agnatha (jawless fishes), Chondrichthyes (cartilaginous fishes), Osteichthyes (bony fishes), Amphibia (amphibians), Reptilia (reptiles) Aves (birds), and Mammalia (mammals) which is where the shrew, moles, rodents, and bats you asked about fall under.)
Class - Mammalia
(Mammalia comes from the Latin word for breast. Vertebrates within the class Mammalia are distinguished from the other classes (reptiles, birds, amphibians, etc) mainly by their possession of mammary glands, but also by the possession of a neocortex (a region of the brain), hair, and three middle-ear bones. Females of all mammal species nurse their young with milk, secreted from the mammary glands. Another interesting fact which is commonly mis-represented is that mammals give live birth, and marsupials are not mammals because of their pouches, but actually Marsupialia is an Infra-class (subcategory) of mammals. Marsupials give live birth and the young then crawl into the pouch while they continue to develop.)
Order - Eulipotyphla / Chiroptera / Rodentia
Eulipotyphla means "truly fat and blind" and includes shrews, moles, hedgehogs, etc.
Chiroptera means "hand-wing" and only includes bats. This order has two sub-orders, Microchiroptera and Megachiroptera. Modern science has actually deemed the distinctions between these sub-orders as outdated, but as with many fields, it will likely take decades for this information to be updated completely, by which time it may be proved wrong yet again by the discovery of new information!
Rodentia is from the Latin verb "to gnaw", and their distinguishing feature is that the upper and lower jaw each have an oversized incisor tooth that grows continuously.
Family - Soricidae / Vespertilionidae / ---
The Etruscan shrew (Suncus etruscus) which I mentioned as being the smallest terrestrial mammal is part of the Soricidae family, along with the five species of moles and shrews that we have in Texas:
- Crawford's gray shrew Notiosorex crawfordi,
- Eastern mole Scalopus aquaticus,
- Elliot's short-tailed shrew Blarina hylophaga,
- North American least shrew Cryptotis parva,
- Southern short-tailed shrew Blarina carolinensis.
Vespertilionidae comes from the Latin word for bat which was "vespertilio" from the word "vesper" meaning "evening".
Genus and Species
The scientific names for things are derived from the Genus and species classifications. The Genus should always be Capitalized, but the species should always be written beginning with a lower case letter.
Q:Why are they called "Etruscan"?
The word Etruscan refers to an ancient civilization/country in the region of Italy. I'm not entirely sure why the Etruscan shrew is named as such, because it's dsitribution is not limited merely to this specific region of the world... but likely, it is where it was first discovered.
Q:What are some examples of extraterrestrial mammals?
The smallest mammal is actually the bumblebee bat, so that would be an example of a non-terrestrial animal. Any animal that lives or roosts on or in the ground is considered terrestrial, and there are many other adjectives used to describe animals that dwell in other habitats. For example:
- arboreal- lives in trees
- aquatic- lives in water (freshwater, saltwater/marine)
- amphibious- both terrestrial and aquatic
- domestic- sometimes used to mean native, but most often refers to any species of animal which has been bred by humans over several centuries, including cats, dogs, horses, and livestock.
- captive- lives in captivity by humans
- migratory- lives in one place for one part of the year, and moves to another place during the other part of the year.
- native- a species that is living in the wild in a region where it naturally occurs
- endemic- a native species that lives only in a very specific, restricted spot and can't be found anywhere else
- exotic - a species that has been removed from the region where it naturally occurs
Q: Is there a reason (or a fun story) behind the "Vespers" name of those teeny bats?
See above guide where I broke down the scientific classification and definitions. :)
Q:Are worms insects?
No, they're not! Worms are animals, but they split off under Animalia into the phylum of Annelids. Worms are actually extremely diverse and their classifications include lots of sub-classes, sub-orders, and sub-families.
Q:So why don't we say "blind as a shrew" instead of "blind as a bat"?
That's a great question, seriously. As a linguistics major, the simplest answer I can offer is that human language and human thought are both very complicated, and closely linked to each other. I've seen this quote blamed on bad science from the 1500s misinterpreting the erratic, darting swoops of hunting bats as poor navigation, and I've also seen it as a misunderstanding of an Aristotle quote.
Q: Is there a way to teach shrews to echolocate?
Some species of shrews actually do echolocate!
To answer the question more directly, though:
For the most part, echolocation is a skill that requires specialized anatomy to produce and interpret the sound frequencies, and those capabilities appeared through the long process of evolution. Therefore, the simplest answer is that it would be very difficult for an individual organism to develop this ability independently. That being said, some humans who are blind have claimed that they learned how to use sound as a way to help navigate their surroundings.
Q:Are bats the only animals that can echolocate?
No! Some (but not all) shrews do, dolphins and whales use echolocation, and some rats have been observed using echolocation in captivity during research.
Q:Are there deaf bats, like ones that can't pick up their echoes? Or mute ones?
That's a complicated question for a few reasons. The field of bat research has plenty left to be discovered because of how challenging it is to track, monitor, collect, or keep them in captivity. It's tricky because if bats are born deaf, the chances of a human researcher or rescuer getting a chance to observe this are already pretty slim, and deafness likely would mean that they wouldn't survive for very long.
Another factor that complicates the answer to this question is that it is believed that certain bat species "hear" the returning echo not only with ears, but feel the vibrations with their specially evolved noses or facial ridges.
That all being said, a prominent bat researcher, Brock Fenton, who has been active since the 1960s, has published several books and studies on bats and their echolocative abilities. In Bat Bioacoustics, he says there are no reported instances of a bat known to have been deaf. More to the point, I believe there is a section in which, if I understood correctly, he states that the genes associated with congenital deafness in bats are genes that are lethal to begin with, meaning that a bat fetus with those genes wouldn't survive in the womb or would die soon after birth.