Large dog breeds in general tend to be even tempered and calm temprement wise, and can make wonderful family pets (and excellent makeshift sofas, for the smaller kids). However, because of their large size, many of them are prone to genetic conditions such as hip dysplasia, which can lead to pain and athristis. They also generally have shorter lifespans compared to their smaller counterparts, and often only live on average for about 7-9 years or so.
I hope that you find the dogs today as interesting as I do! I've included a short summary about whichever breed is pictured under the photograph for more information. Do feel free to correct me if I've got anything wrong.

Komondor
This giant mop- sorry, dog- is, like the smaller sized and better known Puli, a Hungarian breed that was originally intended to guard sheep. Their coat is actually meant to be corded, and the reason it was bred to look like that was so that it could blend into flocks of sheep to keep watch for predators. Unlike the Puli, it only comes in white.

Bernese Mountain Dog
Also called the Berner Sennenhund, these tough dogs are great at hauling carts around, which makes sense, since they were originally a farm dog. Males can easily weigh around 40 to 50 kg, and while they're strong, they're also fairly affectionate and calm around people.

Irish Wolfhound
These tall dogs can eat up to a kg of meat every day. Considering that they can grow up to 80 kgs, though, that's actually a pretty lean diet. They were very successful at what they were originally bred to do, which was to hunt wolves, to the point that the breed was nearly extinct once. This particular wolfhound is named Druid, and he likes to sit on chairs.

Newfoundland
Newfies, as they're otherwise known, are actually amazing in the water and employed often as rescue dogs because of this. They're great swimmers, with webbed feet and a their thick double coat keeps them insulated even in freezing temperatures. On top of all this, they're also very good with children and a surprisingly gentle breed. Nana, the dog in Peter Pan, was actually a Newfoundland.

Great Dane
Despite their giant size, Great Danes are pretty friendly and strangely enough, can make fairly good apartment dogs due to their (normally) laid back temprements. They also tend to consider themselves lap dogs, which can get a little awkward at times. They've been featured in many different forms of media, and the two great danes that most people reading this will likely be familiar with are Scooby-Doo and Marmaduke.

Borzoi
These beautiful dogs, also known as Russian wolfhounds, can frequently weigh over 45kg. With their lean frame and long, silky coats, they certainly don't look like it, though! They tend to be a bit reserved and do need to be kept active, since they are working dogs. They're incredibly graceful to watch in action, too.

Great Pyrenees
As you can tell, these guys are also livestock guardians! They're probably the best known breed among the other dogs that they're related to, such as the Akbash Dog and the Maremma. Because of what they were bred for, they're fairly independent dogs that can be territorial. They're also famously fearless and loyal dogs, too.

Ovcharka
Truly a breed of many names, this dog is very well known in Central Asia, with different regions breeding different sub-breeds which vary in colours, sizes, and appearances. This particular dog comes from Georgia. They're one of the oldest Molosser breeds, and they're very hardy, doing well in cold weather and harsh outdoor conditions. Sadly, because of all their strengths, they're also a popular breed in dog fighting contests.

Malamute
While the average Malamute they might not be quite as big as some of the other dogs on this list and are unfortunately frequently mistaken for giant Siberian Huskies, these lovely dogs are pretty unique- their formidable and powerful build makes them prized for dog sports that require both strength and endurance, such as mushin and bike or skijoring. While they might not be quite as fast as some other breeds, they do very well over long distances and with heavy loads and to top it all off, are usually very good with people (though not always so much with small animals).

Black Russian Terrier
This relatively new breed was created in the former USSR to serve as a guard and police dog- and contrary to both its name and appearance, actually has very little terrier and a lot of other different types of dogs in its heritae. They're very solidly built and make great protectors and tend to bond closely with their owners and handlers. While they are a reconized breed in the American Kennel Club, they aren't very well known yet and are rarely seen in shows.

Leonberer
Named for the city of Leonberg in Germany, these large, proud looking dogs are something of a mascot there. They were supposedly bred to resemble the lions on the city's crest, though by the end of the 19th century were mostly seen as good farm animals. Many prominent individuals, such as Napoleon II, Napoleon III and Otto Von Bismark all owned these beautiful dogs. They nearly died out in WWII, but thanks to a concentrated breeding program, are still around with us today.

St. Bernard
These very large dogs are decidedly a giant breed, clocking in from 64 to 120 kg on average. They're related to mountain dogs in Switzerland, and the current dog is also very similar to the English Mastiff and Newfoundland, due to Newfoundlands being used to preserve the breed around the 1850s and (supposedly) again after WWII. While they're not used for alpine rescues nowadays, they are valued for their performance in activities like carting and pulling weight.
And that's it for dogs for today! But we're not done yet.
That's right, there's still spiders to go!

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Today's spider is the decidedly tiny (less than half a centimeter in length) Sitticus fasciger, a jumping spider that was brought to NOrth America in the mid 20th century. Here's a video of a male spider moving about on someone's hand- as you can see, it's smaller than a fingernail and very, very harmless.

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