Extremely well put, DFR and Kelly, regarding your first comments addressing this post.
Perhaps some perspective about how only wild greens behave would also help?
Out of the over 800 adult green anaconda catches, we had many try and bite - only defensively. (Undoubtedly everyone here knows anacondas are a pretty feisty breed, not unlike many water snake species. I'd never suggest them as a good first snake pet.) Simply, once they tried to swim/crawl away and had no success, then they turned and tried to bite, as a last resort defense. These bites were basically a way of vehemently expressing "leave me alone, you're bothering/scaring me!" They were not super fast strikes, or highly dangerous; typically defensive, "go away" strikes.
I had a bite from an almost 16 foot, large-headed, very pregnant female. Although she had a particularly grumpy personality - I can't blame her, we had surgically implanted a radio trasnmitter in her - and she was pregnanat and thus protective, she typically bit and let go (I was stupid enough to get bit, because I was trying to grab her under cloudy river water where I couldn't see her, I just knew she was there thanks to the transmitter). The only reason the bite was worse was because I pulled, and her tooth snagged on my wrist. (Fight your instincts, never pull when an anaconda bites with those recurved teeth. If they don't let go, you have to be counterintuitive; push slightly further in if you can, the snake will loosen its hold and then you can get free.)Regardless, a bite from a really big dog could have been worse.
Anyway, out of over 800 snakes, and most of those attempting to bite defensively though not succeeding, we had two predatory strikes (almost bites). Two attackes on people, that is. The snakes didn't succeed, but almost; one attempt we even got on film. However, if you have watched your snake feed, you know how fast, violent, and dangerous (if you are the prey!)a predatory bite can be.
So, our rules were simple (at least, after seeing the predatory strike!): Never look for, or as captive owners should word it, nevr handle a large female alone. Period. If those people (one a man, one a woman) had been successfully attacked by the female that went after them, and no one else was around, there is no doubt they would have died. Maybe not eaten successfully, but definitely killed. And, even if we had been around but the first predatory strike was successful, it is quite likely that the person could have had some ribs, or even the spine, broken by the time we had them unwrapped. Don't underestimate the speed at which 200 pounds of snake can move, and the strength they use when they have their prey - they don't want to give it up - try unwrapping a snake from around a caiman - not as necessarily as easy as you'd think.
Second, when you have to catch a large female, use a specific technique. Never assume that your snake is so calm that she will never be a problem. Of course, our wild snakes were never "calm" like a pet. We had a technique that worked fine with just two people - for example, my ex and myself, he's strong, I'm strong for my size (catching many anacondas is a much better workout than Gold's Gym!), but still at 5'3" 105 lbs, I've stood on large snakes and had them lift me entirely off the ground. Stength only goes so far. This technique worked with snakes up to about 16 feet. At that point, a third person will be necessary, even if one of your 2 people is the Hulk.
Once we learned the technique, we went from needing about 5 big people, to just 2 people. The stronger, OR more skilled, handler first goes for the head - for obvious reasons. At the same time, the job of the other person is the keep the 1st 5th of the snake's body - what we call "the evil loop" - from gaining control. The 2nd person job is to keep this 1st fifth from coiling. Sit on it, pull it straight if you are VERY strong, or probably best is to constantly manipulate it, trying to keep it straight, until the snake tires. this can even mean holding the tail and pulling the entire body straight, if possible - simply the tug of war between pulling it straight and the snake resisting, often keeps the "evil loop" from forming.
Regardless, it is this 1st fifth of the body that will immediately try and loop itself over the snake's head AND the handler's hand(s) on it's "neck", since the snake's best option, once it is caught, is to protect it's head, while also trying to push handler #1's hands off of it's head. When I was first learning this through trial and error, I had a snake wrap her coil all the way around my hands (that were holding her head) so that she had me tied up just like handcuffs, and she began pushing my hands over, and off, her "neck", right over her head - not a good position to be in... This is exactly what they will all try and do, no matter what their size, they are always protecting their head. One way to avoid this, is to also constantly switch hands that is holding the head, so that the "loop" cannot get a vantage point (ie. once the loop begins to cover a hand, reach in behind the loop and switch hands holding the head, thus she has to start over forming the loop). It doesn't take long for the snake to tire, about 5 - 10 minutes, luckily.
Even if your snakes are ~calm, having been raised in captivity, this is a good technique to be aware of. And never do what one fellow did, who could win a Darwin Award, since he is no longer with us: he went to feed his retic, and as he needed both hands to unlatch and open the top of the large retic's cage, so he tucked the dead bunny under his chin so both hands were free...you can imagine the rest of the story, hungry retic included.
I hope this description makes sense, it is a bit hard to describe without demonstrating. Rule number one, NEVER handle a 12' or longer retic or anaconda when you are alone. I know you've done it, so have I, but it's just unwise. As with all non-domesticated, wild animals, you can only trust one thing; although you can predict behavior, you can also predict that wild animals are unpredictable. They can behave the same for years, and one day be a little "off", and it is us, the humans, who make the mistake of underestimating them that gets us in trouble. Just ask Roy whats-his-name with the stupid Vegas tiger show...
PS. I just gave a talk about snakes and anacondas to a group of schoolchildren, and I think we now have over 60 8-year old converts of kids who now love anacondas!! Not one of them were afraid of them, either. Not one! Wonderful.
Renee