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denizensofearth:

Norway lemming, Lemmus lemmus

Lemmings in popular culture have been given the role of the blind follower due to the widespread myth that when migrating, the little rodents will follow one another so completely that they will follow other lemmings off a cliff in a mass suicide.  Incredibly, this story was started by Disney with the film “Wild Wilderness” in 1958.  

Lemming populations fluctuate dramatically in a cycles of four years, with populations exploding before dropping close to extinction. The population drops occur naturally (whether they are in response to weather fluctuations, food availability, or some other factor, scientists aren’t certain), but that wasn’t dramatic enough for the film or at all easy to portray, so the filmmakers herded lemmings over a small cliff into a river to create the fake suicide march.  When populations get too dense and food is scarce, lemmings do migrate in large numbers, not en massed but in spread-out groups.(x)

Lemmings live in tundra biomes and feed on grass, sedge, shoots and other plant matter.  They are most closely related to voles and muskrats.  There are over 20 extant species; the Norway lemming and the Brown lemming are the two species with the most dramatic population explosions.  Unlike other rodents, lemmings are conspicuously colored and will behave aggressively towards predators and even humans.(x)

The Norway lemming is found in the Fenno-Scandinavia region and is the only vertebrate native to the region.  It is active both day and night, alternating naps with periods of activity. They spend the winter in nests under the snow.  They migrate in the spring and autumn as changing weather makes certain areas uninhabitable.  They will breed year-round when conditions are good.

(photo)

rhamphotheca:

MIGRATORY FISHES

Diadromous fish:  Truly migratory fishes which migrate between the sea and fresh water.

  • Anadromous: Diadromous fishes which spend most of their lives in the sea and migrate to fresh water to breed.  (ex: Salmon)
  • Catadromous: Diadromous fishes which spend most of their lives in fresh water and migrate to the sea to breed.  (ex: American Eel)

Potamodromous: Truly migratory fishes whose migrations occur wholly within freshwater.  (ex: some populations of Alewife, Brown Trout, and species of Amazonian catfish)

Oceanodromous:  Truly migratory fishes which live and migrate completely in the sea.  (ex: Tuna)

(via: Wikipedia)

(photos: T - spawning Sockeye Salmon by TheInterior; B - American Eel by Claude Nozeres, World Register of Marine Species; Alewife via The Nature Conservancy)

rhamphotheca:

The Catfish That Strands Itself to KILL PIGEONS!!!

by Ed Yong

In Southwestern France, a group of fish have learned how to kill birds. As the River Tarn winds through the city of Albi, it contains a small gravel island where pigeons gather to clean and bathe. And patrolling the island are European catfish — 1 to 1.5 m long, and the largest freshwater fish on the continent. These particular catfish have taken to lunging out of the water, grabbing a pigeon, and then wriggling back into the water to swallow their prey. In the process, they temporarily strand themselves on land for a few seconds.

Other aquatic hunters strand themselves in a similar way, including bottlenose dolphins from South Carolina, which drive small fish onto beaches, and Argentinian killer whales, which swim onto beaches to snag resting sealions. The behaviour of the Tarn catfishes is so similar that Julien Cucherousset from Paul Sabatier University in Toulouse describes them as “freshwater killer whales”.

Alerted to the fishes’ behaviour by local fishermen, Cucherousset watched them from a bridge overlooking the island. Over the summer of 2011, he filmed 54 attacks, of which 28 percent were successful…

(read more: Discover Magazine blogs)                    

(watch video here)

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Reference:  Cucherousset, Bouletreau, Azemar, Compin, Guillaume & Santoul. 2012. ‘‘Freshwater Killer Whales’’: Beaching Behavior of an Alien Fish to Hunt Land Birds. PLOS ONE http://dx.doi.org/10.1371/journal.pone.0050840

rhamphotheca:

Newly Discovered Hexapods!

Three bizarre-looking springtails, tiny insectlike creatures, have been discovered in a Spanish cave.

by Our Amazing Planet staff

Springtails are amongst the most ancient and widespread animals on the planet. Like insects, they have six legs, but are small, more primitive and lack wings. They usually have a furca, or a tail used to spring away from danger, hence the name “springtails.” Many cannot be seen with the naked eye; the largest species is about 0.24 inches long (6 millimeters).

The three species — dubbed Pygmarrhopalites maestrazgoensis, P. cantavetulae and Oncopodura fadriquei — are very different from one another. But each of the new species has the requisite springy tails and hairy, tiny bodies, resembling Lilliputian monsters. One of them, O. fadriquei, lacks eyes.

They were found by researchers from Spain’s University of Navarra in the isolated Maestrazgo caves in the Teruel region of Spain, at elevations up to 6,560 feet (2,000 meters)…

(read more: OurAmazingPlanet)         (photo: R. Jordana, E. Barquero)

rhamphotheca:

Ural Owls (Strix uralensis), Estonia

Photo: Sven Začek

She looks sweet grooming her chick, but don’t mess with mom’s nest: Ural owls are aggressively territorial. “I’ve made an ‘agreement’ with the females that the price to band and measure one nestling is six hard punches on the head,” says Finnish ornithologist Pertti Saurola.

(via: National Geo)

fyeaheasterneurope:

Archaeologists in Bulgaria say they have uncovered the oldest prehistoric town found to date in Europe.

The walled fortified settlement, near the modern town of Provadia, is thought to have been an important centre for salt production.

Its discovery in north-east Bulgaria may explain the huge gold hoard found nearby 40 years ago.

Archaeologists believe that the town was home to some 350 people and dates back to between 4700 and 4200 BC.

That is about 1,500 years before the start of ancient Greek civilisation.

The residents boiled water from a local spring and used it to create salt bricks, which were traded and used to preserve meat.

Salt was a hugely valuable commodity at the time, which experts say could help to explain the huge defensive stone walls which ringed the town.

(More at BBC.)

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