Naturalis meets North Carolina: News about ShrewsPosted on 05-10-2017 by Becky Desjardins
Naturalis meets North Carolina: News about Shrews
One of the first tasks I had to do upon arrival in North Carolina was try to get my hands on some Blarina. Blarina are a type of shrew, tiny insectivores that resemble mice or voles, but they have very silky fur and some mean looking teeth. Shrews are found nearly everywhere in the world, but I really wanted some from America. The reason is because one of the genuses of shrews found here, Blarina, is venomous. Naturalis has a new exhibit opening shortly about venom, and we want to have some shrews in the show!
Some snakes are venomous, and of course some insects too, but there are not very many types of mammals which have venom. Only some types of bats, platypus (males have a spur in their hind food that can deliver toxins during a fight with another male) and a few types of insectivores. Which brings us to the shrew. A few different genuses of shrews have a venomous bite: special glands in the lower jaw produce venom which is channeled through a groove in the lower incisors and delivered to the prey via a bite.
Shrews have a very high metabolic rate, which means that they have to eat all the time to stay healthy and active. In captivity they have been known to eat ½ to 2 times their body weight per day! In order to be certain that they have access to food all the time, including during the depths of winter, venomous shrews cache prey such as worms, insects, and snails. These prey items are not dead, they are instead in a comatose state brought on by the toxins in the saliva of the shrews. However, it is important to note that the exact purpose of venom in shrews is still debated by mammalogists, no one knows for sure.
Lucky for me, Benjamin Hess, the mammal collection manager happened to have some “good looking Blarinas” in the freezer. I have preserved 3 of these Southern short-tailed shrew (Blarina carolinensis) in ethanol, and plan to ship them back to the Netherlands next week, where they will be prepared to go on exhibit. However, I learned an interesting fact from Benjamin. The European water Shrew, (Neomys fodiens), is also venomous! After doing a bit of research, I found out that both of these shrews are venomous in the same way: toxic saliva delivered via grooves in the teeth into the prey item. Who knew we had venomous shrews in our own backyards in the Netherlands? Hopefully in a few weeks visitors will be able to see both European and American Shrews in the Venom exhibit.
Rode-Margono, Johanna E and K. Anne-Isola Nekaris, 2015. Cabinet of Curiosities: Venom Systems and Their Ecological Function in Mammals, with a Focus on Primates. Toxins 7(7), 2639-2658