1. Thebeaver (genus Castor) is a primarily nocturnal, large, semiaquatic rodent. Castor includes two extant species, the North American beaver (Castor canadensis), which is native to North America, and Eurasian beaver (Castor fiber), which is found in Eurasia. Beavers are known for building dams, canals, and lodges (homes). They are the second-largest rodent in the world (after the capybara). Their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. The North American beaver population was once more than 60 million, but as of 1988 was 6–12 million. This population decline is the result of extensive hunting for fur, for glands used as medicine and perfume, and because the beavers' harvesting of trees and flooding of waterways may interfere with other land uses.
2. ARTICLE FROM THE JOURNAL SCIENCE: ‘Jurassic beaver’ find stuns experts
The discovery of a Jurassic beaver-like creature suggests early mammals were more diverse than thought. The discovery of a new, remarkably preserved fossil of a beaver-like mammal that lived 164 million years ago is shaking paleontologists’ understanding of early mammals. Looking as if it was put together from pieces of platypus, river otter, and beaver, the creature was nearly half a metre long and weighed about half a kilogram. This makes it the largest mammal ever found in the Jurassic Period, from 200 million to 145 million years ago. The fossil of the semi-aquatic mammal Castorocauda lutrasimilis was discovered in the middle Jurassic Jiulongshan formation in Inner Mongolia, China, by Qiang Ji at Nanjing University, and colleagues. It boasts the oldest fossil fur ever found. Paleontologists had long thought the mammals living under the feet of the dinosaurs were tiny shrew-like animals. But recent discoveries have challenged this notion.
In 2005, Repenomamus giganticus from China showed that land mammals had reached a meter in length about 130 million years ago, during the Cretaceous Period. But the newly found fossil  reveals that early mammals were also far more diverse than thought. The discoveries “are completely reconfiguring our understanding of Mesozoic mammals,” says Hans-Dieter Sues of the Smithsonian Institution’s National Museum of Natural History.
Castorocauda was preserved in exquisite detail, flattened in sediments at the bottom of an ancient lake. Hair impressions surround the body, which includes a 20-centimetre-long flat, beaver-like tail. Two slabs of sedimentary rock include most of the body and part of the skull.
The animal had “a full mammalian pelt, with guard hairs and under fur, and scales on the tail” like a modern beaver, says Zhe-Xi Luo of the Carnegie Museum of Natural History in Pittsburgh, US, and one of the team.
Castorocauda’s webbed feet, limbs and broad flat tail are adapted for swimming, and its teeth specialized for catching fish, making it the earliest mammal known to live partly in the water. Another 100 million years would pass before ancestral whales and manatees turned to the water.
The creature probably lived like a modern platypus, says Luo, “digging a tunnel to nest and lay eggs, and going from the tunnel into the water to feed”.
The discovery shows that fur and modern skin structures and warm-blooded metabolism originated very early in mammals. “Hair keeps us warm, and sweat glands help us to dissipate heat, so skin is part of the adaptation to constant body temperature,” Luo told New Scientist.
3. DAMS: Beavers were almost eliminated from three continents before people realized the true value of nature's engineers. Because beavers build their stick-and-mud dams in streams flowing through shallow valleys, the flooded area becomes freshwater wetlands. Such wetlands are rated by ecologists and economists as the land’s most beneficial ecosystem. Because beaver dams create mini-reservoirs that keep water on the land longer, they can alleviate both droughts and regional floods. Beavers build leaky dams that slow the flow of streams, creating quiet water nurseries for fish and many other organisms. About half of the rare species require wetlands during their life cycles, according to US EPA. Slowing the flow also allows time for wetland microorganisms to detoxify pollutants, such as pesticides. Beaver dams accentuate the normal filtering function of wetlands by collecting silt, and there can be 90% less sediment in the water downstream. Such water cleansing results in healthier downstream habitats, and less costly treatment is needed at plants to produce drinking water for people.
4. Lodges. Beavers build and maintain houses called lodges. There are two main types, the conical lodge and the bank lodge. The most recognized type is the conical shaped dwelling surrounded by water. It is made from sticks, mud and rocks. One of the primary reasons beavers build dams is to surround their lodge with water for protection from predators. The second type of lodge is the bank lodge. It is typically excavated into the bank of a large stream, river, or lake where the water is too deep or fast moving to build the classic conical lodge.
Within each lodge beavers will hollow out a chamber where they sleep, eat, groom each other, and the baby kits are born and nursed each spring. Beddings of grasses, reeds and wood chips are changed regularly. In order to breathe fresh air beavers do not apply mud to the peak of the lodge, creating a ventilation shaft. Note: If you have an opportunity to visit a beaver lodge on a very cold winter day, look very closely and you may see the beaver's breath escaping from this chimney-like peak, or even hear the murmurs of the beaver family inside!
Each lodge contains at least two water-filled tunnels leading from the chamber to the pond so the beavers can enter and exit the lodge underwater without being spotted by predators. The walls of the conical lodge are very strong due to layers of mud and sticks, and are extremely insulated. Even with subzero outside temperatures it will not drop below freezing inside the lodge due to retained body heat from the family of beavers.
5. SIX SPECIES THAT MATE FOR LIFE:
Gibbons are the only species closely related to humans who form long-term monogamous pair bonds. Mated gibbons often duet, singing complex songs to literally shout their love from the tree tops – or, more accurately, to defend their territory from any other gibbons looking for a home. So if you’re out of ideas for something romantic to do this Valentine’s Day, why not symbolically adopt a gibbon to show your sweetie your long-term devotion? (Alternatively, you could always serenade your special someone with a series of whoops!)
Sandhill cranes are one of conservation’s biggest success stories, and they also are one of the most romantic! Sandhill cranes seek out a mate before their annual migration to their breeding grounds and form a pair bond by unison calling. When they arrive at the breeding grounds, sandhill cranes perform elaborate dances as part of their mating ritual. Once their mate is suitably impressed by their sweet dance moves, the sandhill cranes begin to nest and form their lifetime of bliss. These pair bonds last until one of the cranes dies – a true mating for life scenario.
Prairie voles are unique amongst their vole contemporaries for their tendency to mate for life. Studies have found that prairie vole brains respond differently to the chemicals released during social bonding and mating than other voles. This means that the bonds they form are so strong that male prairie voles often resist during vole “temptation scenarios”, in which an unfamiliar female is introduced. Rather than sidling up to the hot new vole in town, male prairie voles spend their days with their mated partner, snuggling and sharing responsibility for raising the family. Aww.
Unlike ants, where the queen doesn’t limit herself to just one mate, termites form a lifelong pair bond (which, as the video below shows, proves that love is blind and also sometimes icky). Termites will land on a log, find their termite soulmate, and begin building their life together within a few hours of meeting. Of course, termites sometimes get buyers’ remorse – a species of termite native to California occasionally sees either the male or female termite abandon their new mate within the first 90 minutes of their “marriage” to seek out someone better. Sometimes even the truest of termite love doesn’t last.
Barn owls are notable for many things – their eerie call, their ability to locate prey based on sound alone, and their subsequent ability to swallow prey whole – and their romance skills can be added to their resumés! Not only do they mate for life, but male barn owls pull out all the stops to impress their lady loves. During courtship, male barn owls will go out of their way to hunt more in order to present their mate with extra food. Nothing says “I love you” quite like a dead mouse in your nest! (Note: this may not be the best way to surprise your human Valentine…)
Beavers are another of the rare mammal species who mate for life. Beavers live in colonies which are made by mated beaver pairs and used to raise their children. After about two years, beaver kits move out of Mom and Dad’s dam to find their own beaver spouse and have up to 20 years of marital bliss. Should the worst happen and one of the beavers come to die, the still-living beaver will seek out another mate to find love anew.
6. BEAVER TEETH: Beaver Teeth Have Iron Advantage (transcript of Podcast)
Ah yes. The ol' fluoride rinse at the dentist. Not pleasant. But hey, good for your teeth, right? Well now materials scientists have been able to figure out why—by mapping the nanostructure of tooth enamel. If you zoom way in, tooth enamel looks almost like the weave of a basket. And in between those crystalline nanowires, [scientists have] discovered a sort of amorphous glue. And that's where the fluoride hangs out, helping to stave off an acid attack of the enamel—in other words, a cavity. But the researchers found something that works even better than fluoride: iron. And they found it in beaver teeth. "Beavers don't get cavities. Chewing through wood is a very good way to clean your teeth." But another reason, they say, is the iron-enriched glue in beaver enamel—which was even more acid-resistant than fluoride-treated enamel. The findings are in the journal Science. [Lyle M. Gordon et al, Amorphous intergranular phases control the properties of rodent tooth enamel] Of course iron-rich enamel comes with an unfortunate side effect: reddish-brown teeth. But [scientists say that] future human dental treatments that employ iron might find a way around that. "We have the entire periodic table to play with minus a few things that are not too healthy. So I'm sure we can come up with a way to do what the beaver does but do it better and do it in a way that still maintains a nice smile."