| Welcome to Carnivora. We hope you enjoy your visit. You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile and voting in polls. Registration is simple, fast, and completely free. Join our community! If you're already a member please log in to your account to access all of our features: |
| American Water Shrew - Sorex palustrus | |
|---|---|
| Tweet Topic Started: Jul 4 2012, 02:49 PM (1,761 Views) | |
| Taipan | Jul 4 2012, 02:49 PM Post #1 |
![]()
Administrator
![]()
|
American Water Shrew - Sorex palustrus![]() Scientific classification Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Soricomorpha Family: Soricidae Genus: Sorex Species: Sorex palustris Description The water shrew (Sorex palustrus) is the world’s smallest warm-blooded diving species. It is a relatively large shrew, with a slender body, a long tail, and a long, pointed, highly moveable snout, which has conspicuous vibrissae (specialised whiskers). The snout is almost incessantly rotated. The feet of the water shrew have a fringe of stiff hairs, called fibrillae, which increase the surface area to help propel the water shrew as it swims. The water shrew has dark brown-black fur covers the upperparts of the body, sometimes with grey frosting, while the fur underneath is white, often tinged with grey or brown. The chin is considerably lighter than the rest of the body, and the tail is distinctly dark above and light below. The male and female water shrew have a similar appearance, but the male is typically larger and heavier than the female. The genus name Sorex is derived from the Latin word ‘soric’, which means ‘shrew mouse’, while this species’ specific name palustris means ‘dwelling in marshes’. Up to ten different subspecies of the water shrew have been recognised. Range The water shrew occurs in the cool, boreal, montane regions of North America, Canada and Alaska. ![]() It ranges from Labrador, Nova Scotia and New England, across Canada to east-central Alaska, and south to the northern Great Lakes region, and is found south along the western mountain ranges of mid-California, Nevada, Utah and New Mexico in the U.S. Water shrew populations are also known from the Appalachian Mountains, ranging from south-west Pennslyvania to North Carolina, Tennessee and Georgia. The water shrew has been recorded as far north as the Yukon Territory. In Wisconsin, the water shrew is mostly confined to the northern part of the state. Habitat The water shrew occurs along small, usually fast-flowing, cold-water streams with thick, overhanging riparian growth. It is also found around lake, ponds, bogs and marshes. Logs, rocks and crevices are all common features of water shrew habitat. Biology Rarely found far from water, the water shrew is extremely well adapted to its aquatic lifestyle. Although the eyes of the water shrew are small and vision is poor, it has acute hearing and an excellent sense of smell. In addition, the hairs on the feet trap air, allowing the water shrew to run across the surface of water. The water shrew regularly dives under the water to capture prey or to avoid danger, sometimes remaining below the surface for over 30 seconds at a time. During dives, air bubbles trapped in the fur reduces heat loss, although the bubbles also make the water shrew fairly buoyant, meaning that it must paddle vigorously in a walking motion to propel itself forwards. Mostly active during the day, the water shrew consumes a large amount of food given its small size. Due to its high energetic demands, the water shrew can only survive for about three hours without food. Aquatic insects form the bulk of the water shrew’s diet. Slugs, snails, earthworms, small fish, amphibians and spiders may also be taken, and the water shrew may occasionally feed on terrestrial invertebrates such as grasshoppers and crickets. The water shrew forages using its sensitive nose, which has specialised hairs or whiskers, called ‘vibrissae’. During times when prey is abundant, the water shrew may cache food in hollow logs or crevices, returning when food is scarce. ![]() Reproduction Breeding occurs from February to August in North America. The nest is typically made from grass and plant material, with a depression in the centre, and is placed close to water, usually in an underground burrow, on a raft of logs or in a beaver lodge. The water shrew may also construct tunnel systems, or it may use those of other species. The water shrew may have up to three litters a year, each with between three and ten young. The gestation period lasts for around three weeks and, following birth, the young water shrews develop rapidly. The water shrew does not reproduce until after the first full winter, and it has a short lifespan, usually only living to about 18 months. |
![]() |
|
| Taipan | Jul 4 2012, 02:51 PM Post #2 |
![]()
Administrator
![]()
|
Diving Shrews: Heat Before You Leap ScienceDaily (July 3, 2012) — How does the world's smallest mammalian diver survive icy waters to catch its prey? A recent study of American water shrews to be presented at the Society for Experimental Biology meeting in Salzburg on 1st July has surprised researchers by showing that the animals rapidly elevate body temperature immediately before diving into cold water. This behaviour is unexpected because lower body temperatures enable diving mammals to stay underwater for longer, so heating up doesn't make sense. This is because animals use up oxygen more quickly when they are warmer. According to Professor Kevin Campbell of the University of Manitoba, who led the study, "This finding goes against prevailing dogma regarding the physiology of divers. Divers, especially small ones, have always been expected to try to maximize their underwater endurance." Campbell added that this behaviour indicates the shrews are optimising factors other than just dive duration. Given that they are highly proficient aquatic predators, an elevated body temperature presumably heightens foraging efficiency. Large animal divers, like seals and penguins, have been studied extensively, but these findings show that small diving animals deserve attention as well. ![]() The reaction time of the American water shrew is 10-20 times faster than a human's. Life at the limit Compared to other diving mammals, the shrews carry the least amount of oxygen under water and use it up the most quickly. Typical dives thus last only 5-7 seconds. Being so small also makes them lose heat the fastest. Dr Roman Gusztak, who participated in the study, said: "The shrews are likely surviving at the limits of what is possible for a diving mammal. They must continually feed to provide for their voracious appetites but have to contend with very short dive durations and the constant threat of hypothermia." Exactly how the shrews warm themselves is unknown. Often, the shrews elevated body temperature while they were simply sitting still at the water's edge before a dive. The researchers believe the shrews are shivering or using their brown fat to generate heat. As part of this study, the researchers observed the shrews' behaviour when diving into water of different temperatures. They compared the length of the shrews' dives in warm and cold water and also monitored the shrews' body temperatures before, during, and after dives. http://www.sciencedaily.com/releases/2012/07/120703190119.htm |
![]() |
|
| 1 user reading this topic (1 Guest and 0 Anonymous) | |
| « Previous Topic · Mammalia · Next Topic » |












5:04 AM Jul 12