No more river dolphins?
Chinese river dolphin: extinct?
An international team of scientists recently spent six weeks on China's Yangtze River looking for the endangered river dolphin. They were unable to find any, leading some to believe the animal has been driven to extinction.
The 8-foot-long mammal has lived in China's longest river for 20 million years. But massive increases in fishing, shipping and development have pushed the creature to the brink. The last confirmed sighting occurred in 2004, and the last captive dolphin died in 2002.
By definition, scientists don't consider an animal extinct until 50 years after the last sighting in the wild. And the recent survey focused on the river's main channel - it's possible some dolphins may yet hang on in the tributaries. But even if they do, it's unlikely the population can ever recover.
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why is the chinese river dolphin extinct?
The dolphins have been killed off by overfishing and an increase in shipping along the Yangtze. Illegal fishing efforts sometimes even used explosives to capture this rare dolphin. The dolphin is also nearly blind and was regularly wounded by passing ship propellers.
why are dolphins getting killed?
According to the article:
Also, pollution is killing the fish which these dolphins eat.
how many kinds of dolphins are there?
33 species of marine dolphins, 4 species of river dolphins, and 6 species of porpoises.
4 species of river dolphins?i read in a book and it stated that there are actually 5 species of river dolphins...
1. Amazon River Dolphin (Inia geoffrensis)
2. Chinese River Dolphin (Lipotes vexilifer)
3. Franciscana (Pontoporia blainvillei)
4. Susu (Platanista gangetica)
5. Irrawaddy Dolphin (Orcaella brevirostris)
Different scientists will classify species in different ways. The American Cetacean Society lists four river dolphin. They consider the Irawaddy dolphin to be more closely related to the common dolphin.
Debates over taxonomy aside, the important thing is that many marine mammal populations are threatened with extinction. Whatever we choose to call them, we must protect them before they disappear.
they are very scared
im doing a project on dolphins can i get more info
sorry, all i know about dolphins is that they are mammels snd that they feel like rubber. yay!!!
why are the dolphins getting killed is it because of pollution or illegal fishing or is it just both of them.
See the comments above. Illegal fishing is killing the dolphins directly, while pollution is killing the fish they eat.
that is so sad that the world has came to this, animals dying from pollution!
noooooooo!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! dolphins r my fave animal!
yea that is so sad
ah man i love those things! that's to bad , and SAD!
ok. lets wait the full 50 yrs (actually last sighting was 2004, now it's 2009 so 50-5=45yrs) to see if they are really extinct, then declare them extinct. maybe a new dolphin may appear along the way! who knows with evolution.
Evolution does not work that fast with large organisms.
That's not entirely true. If one large organism is born with a mutation and mates will another that has the same mutation or genes that can compliment that mutation, they may have descendents that contain this mutation and so on so forth. This may be over a few years or decades.
If we were talking about organisms with short lifespans that reproduce early and often, like bacteria, then you would be right: you can see evolution happen in just a few years or decades.
But in an animal with a relatively long lifespan, like a dolphin, 50 years is not long enough for a population to become an entirely separate species. You may start to see a prevalence within a group of a trait that you don't see so widely among the population as a whole, but that group is still part of the same species.
wow. u guys are being all theoretical and technical. i was just shooting out some sarcasm at the declaration of extinction before actual confirmed extinction. and with all the changes going on-enviromentally- i'm just saying anything can happen.
evolution is change[in alleles] over time[w/in a population/group] and speciation is when some individuals in the group can no longer successfully mate/reproduce with the other members-thus there are probably two/more species present[in very short-could be better summary]. but an important part of evolutionary change is random chance. yes, a new species is very very very very very improbable, but not totally impossible.
i mean one could say human evolution/speciation was very very very improbable, and yet here we are. all our human characteristics, chance selections within given situations.
Hmm.
I'm afraid that sarcasm doesn't always work very well in written-comment dialogs. Am I being sarcastic right now? I don't even know.
I think that one could say that "human evolution/speciation" was the opposite of very, very, very improbable. Short of the human genetic line going extinct, evolution and speciation was necessarily going to happen. Nothing stays the same forever, because the "given situations" (i.e., environmental pressures) are always changing.
So I suppose in some sense anything could happen when it comes to dolphin evolution. But it is so incredibly unlikely that it's not really worth discussing outside of science fiction. Evolution happens through random mutations, right? But these are tiny random mutations. Our bodies try not to have genes mutate when cells replicate, because if the mutations do anything at all, they usually do something that's not very helpful to survival. So when an organism speciates, it's because lots of these random, infrequent, tiny mutations have accumulated. In order for that to happen, a species needs time. The longer the lifespan and reproductive cycle, the more time is needed. Tiny organisms that reproduce quickly and frequently can build up changes more quickly, but something like a dolphin is just not going to totally speciate from one generation to the next.
Like, it could happen, but I would sooner place money on the chances that space dragons will fly into my cubicle and start fondling me inappropriately this afternoon. Because I guess that could maybe happen too. But huge mutations turning something suddenly into another species just don't happen. This is for the same reason that handling radioactive sludge doesn't give turn you into a teenage mutant ninja turtle, or give you x-men style super powers. It gives you cancer. That's what happens when a ton of random mutations happen. (Er... Now I do think I'm being a little sarcastic.)
It's an interesting discussion, but I don't think that's how evolution has ever worked.
Space dragons, eh? That's more than I ever wanted to know about you JG.
Don't worry, it didn't happen.
I have to stop putting money on that.
I feel bad for those dolphins.I don't think they deserved it.
it must suck if those dolphins are dieing because others would probably love to see them
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