Predation?

[starbug1]

I was reading about symbiosis and I wondered about parasitism. Couldn't this also be a form of predation? A parasite acts the predator in a way because sometimes it ends in the death of the host, or, possibly in this case, prey.

 

So, under what circumstances can parasitism be considered predation and what are some good examples to back this?

[bascule]

Parasites feed off a living host. Predators feed off of dead ones (which they hunt, kill, and devour)

 

Isn't it just that cut and dry?

[jeskill]

I think so. In a host-parasite relationship, killing the host is usually not beneficial to the parasite because the host is either the habitat, food source or both. In a predator-prey relationship, it is necessary to kill the prey.

 

I can't really think of a situation in which the parasite benefits from killing the host, unless killing the host allows for better dispersal of the parasite. But it's still not a predator-prey situation, because the host is not killed in order to consume more energy.

[Bluenoise]

Or the host may have some sort of natural defense against parasites. In that case it maybe beneficial to kill the host. I know there are certain insects that lay larva in live hosts. Eventually this kills the host and once the parasitic larva has consumed all it needs it matures and leaves the dead host behind.

[Mokele]

But those are technically referred to as "parasitoids" (such as "parasitoid wasps and flies").

[starbug1]

Parasites feed off a living host. Predators feed off of dead ones (which they hunt' date=' kill, and devour)

 

Isn't it just that cut and dry?[/quote']

 

 

I would have thought so too, yet I was reading that some forms of parasitism can be considered predation. The most prominent answer I could think of to fit this scenario was parasite borne diseases and parasite manipulation of a host, which can also be transferred to another host. Parasites such as ticks and the like cause many deaths in the animal kingdom, and they also kill humans. A parasite manipulation of a host would be like an infected ant, which gets eaten by herbivores and then could be fatal in these animals. Even so, this sounds more like "assisted predation."

 

I can't really think of a situation in which the parasite benefits from killing the host, unless killing the host allows for better dispersal of the parasite.

 

This is something I thought of as well. But I was wondering about specific examples that might show this. mabye less rare cases.

 

But it's still not a predator-prey situation, because the host is not killed in order to consume more energy.

 

This is one of the problems this parasitism-predation presents. But if it's not energy they are obtaining, then it's possible it may be something else. This moot question was shown in my bio textbook, and I didn't think there could be much reality to it. But, after all, the other forms of symbiosis switch back and forth also. Commensalism can be turned into parasitism, and mutualism can sometimes be commensalim. So the symbiotic relationships are ambiguous.

[Euclid]

Look, Parasites NEED the host alive for there own benefit for a period of time, predators kill and ask questions later. It is just that simple

[starbug1]

OHHHHHHHHH! Now I get it!

[bombus]

Are cows parasitic on grass then? I suppose it could be mutualistic symbiosis, as grazing stops other plants colonising and shading out the grass (which is good for the grass), but at the same time prevents the grass from flowering and seeding (not so good). There is only benefit to the cow.

[starbug1]

Are cows parasitic on grass then? I suppose it could be mutualistic symbiosis, as grazing stops other plants colonising and shading out the grass (which is good for the grass), but at the same time prevents the grass from flowering and seeding (not so good). There is only benefit to the cow.

 

 

No. wrong idea. I don't have any doubts that what we currently know is cut and dry. I'm concluding this by saying that the writers of my textbook had intent to be elusive; it was one of those lame cliffhangers. "But what if?...."

Therefore they had no scientific backing for their statement, only a loosely based research proposition.