| Most of that reply was taking issue with using predator instead of carnivore or more broadly 'consumer', which is fair. Actually I'm not sure if that was what you were getting at, because this was in response to me pointing out omnivores are a half trophic step between herbivore and predator (consumer): > We are not predators and are not herbivores. > swines are not herbivore but not predators. Yet.. both of those examples are exactly that, omnivores, and both are also sometimes functionally predators. And it absolutely follows that you can put an omnivore at half trophic step between a primary consumer (i.e. a predator of herbivores) and an herbivore. The way trophic levels are described are in fractional numbers of the mean trophic level of what you eat. Predator is a functional group rather than a descriptor trophic level, but when it comes down to it very few animals are pure functional specialists and very rarely does one sit perfectly at a given trophic level - to use your snakes example, they absolutely eat herbivores sometimes even if they are usually eating things that eat animals. Cows consume the occasional insect, I've seen algae-specialist green sea turtles opportunistically eat dead fish, and some shark species eat a non-negligible amount of grass. But I'm going to continue calling sea turtles grazing herbivores and sharks consumers and predators, because that is true to a first approximation. Regarding ecosystem complexity, I don't believe I mentioned it other than length of trophic chains. However I'll point out that this > Oceans are not absolutely more complex than terrestrial life and why should they be? Life on Earth evolved over hundreds of millions of years, it makes sense that it adapted to every ecosystem the Earth has to offer. Doesn't follow. Sure, life evolved everywhere, speciation occured and niches have been pretty well filled. That doesn't mean ecosystem complexity is the same everywhere, there are a number of identified drivers of species richness and functional diversity (e.g. latitude) and decades of theory to try to explain why, because a rainforest is more complex than a sweetgrass prarie, and a coral reef is too. A rainforest probably beats a lot of marine ecosystems, say a soft sediment continental shelf in terms of complexity due to greater species richness, simply more connections between species at many levels and lots of niche partitioning. Can't say I understand your point about food chains being longer due to microscopic primary producers. That is still the energetic pathway that feeds into the rest of the ecosystem. > a bit longer doesn't mean what the original comments was about. My reading of that comment was exactly that, that marine food chains are longer. That commenter exaggerated a bit the degree to which that is true. That study I linked provides some plausible mechanisms of why that may be. |
omnivores are not something in between a predator and an herbivore.
we are facultative carnivores, we can eat vegetables, but we are not predators.
> And it absolutely follows that you can put an omnivore at half trophic step between a primary consumer (i.e. a predator of herbivores) and an herbivore
it doesn't follow.
Pigs are prey too, but they can eat meat.
Above all there is us, humans, but, generally speaking there are the apex predators, which is not "all the predators".
A pig or an ape sits above an ant, which is one of the most formidable predator of the animal kingdom.
> they absolutely eat herbivores sometimes
of course they do.
it doesn't change the fact that some of their preys are predators themselves.
because they eat them for their meat, not because they are labeled "preys" in the encyclopedia.
> That doesn't mean ecosystem complexity is the same everywhere
if that's the argument, it doesn't follow that watery ecosystems are the same everywhere too and that they are more complex than any other ecosystem.
> Can't say I understand your point
was quoting the original comment which goes like this
algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator
at the zooplankton level you already have whales eating it.
end of the chain.
so zooplankton is the equivalent of terrestrial ants that eat plants and then some bird eats the ants and then some small predator eat the bird and then some bigger predator eat the small bird eater then some even bigger predator eat it, until you arrive to an apex predator (a bear, for example).
What's the difference?
> that marine food chains are longer
but not because algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator
but because
eukaryotes-bacteria-bacteria-bacteria-bacteria-bacteria-bacteria-Valonia ventricosa