I don't have much against keeping animals in captivity, generally speaking. I do have something against causing unnecessary suffering and pain to animals, for example the way we catch dolphins to send to aquariums all over the world - aquariums that are usually very small, in fact I'd have to say probably every single aquarium in the world is too small for an orca or a dolphin or a whale to have even a remote chance at a normal-ish development and life-cycle. That doesn't mean that some species shouldn't be kept in captivity in order to keep them from disappearing, though. Species survival trumps humane concerns, imho. At least til we get a reliable way to resurrect individual species from the dead. Go Japan - the only country with enough resources, smart and crazy scientists and just plain crazy everything to have a decent chance at making that happen in my lifetime. I want to see a real, live Woolly Mammoth, dammit!
If you need to kill an animal for food or for its skin or whatever, don't cut its throat and leave it to die in agony and anxiety. Same with humans. Just get the killing over with simply, quickly and efficiently - then go about your business. No need to be rude about it.
I also have nothing against farmers and poor villagers protecting themselves and their livestock from predators - to an extent. If you start eradicating wolves in France and crocodiles around the Philippines then you're kind of going too far.
We supposedly have about 8.7 million different species on the planet. Homo sapiens is just one of them. Sure we're the most powerful. Sure we're the only one so far that's developed the capacity to annihilate all life on planet (hmmm, would cockroaches or bacteria on the ocean floor survive?). But any one of those could have the cure for cancer, or whatever disease killed your child or your mother or father.
An international team of scientists... put the count at 6.5 million species on land and 2.2 million in the ocean for a total of just under 9 million. And they said 86 percent of all terrestrial species and 91 percent of marine species are yet to be discovered, described and catalogued.
During the last century, decreases in biodiversity have been increasingly observed. In 2007, German Federal Environment Minister Sigmar Gabriel cited estimates that up to 30% of all species will be extinct by 2050. Of these, about one eighth of known plant species are threatened with extinction.Estimates reach as high as 140,000 species per year (based on Species-area theory). This figure indicates unsustainable ecological practices, because few species emerge each year. Almost all scientists acknowledge that the rate of species loss is greater now than at any time in human history, with extinctions occurring at rates hundreds of times higher than background extinction rates.Again, species loss rates are just estimates, but given that we only know about 9-14% of the species that live on the planet, it kind of sucks that we're losing things we don't even know exist. Many of these, via the Law of Unintended Consequences (http://en.wikipedia.org/wiki/Unintended_consequences) may well have important roles to play in processes that we might not even know are crucial to humans, such as binding this or that chemical. We simply don't know how much we don't know.
To illustrate, no-one knows how much Methane Clathrate is bound in ice in various regions, or what will happen to it and how much it will effect a warming Earth in our lifetime. See http://en.wikipedia.org/wiki/Methane_clathrate#Methane_clathrates_and_climate_change
But anyway, cool video. Cool crocodile. Let's keep animals like that alive so people and kids can Ooh and Aah about them and be inspired by nature instead of having their heads stuck inside cities glued to television screens all the time. Which is kind of the function of zoos - but the problem is that keeping animals in captivity for your enjoyment is a bit of a mixed thing - not terribly cool for animals that normally have very wide-ranging habitats or are pretty darn intelligent.
Do no evil. Don't be a dick. Hey, look - a big crocodile!