| > we are facultative carnivores, we can eat vegetables, but we are not predators. No, we are omnivores, both behaviorally and physiologically. As I mentioned, predator is a functional class, but we are absolutely are predators - predation is killing something to eat it. Perhaps you mean we aren't obligate predators. Regarding the trophic position of omnivores and the existence of multiple trophic levels of consumers, which I acknowledged in my first post, it doesn't really matter - you can calculate trophic position by the mean trophic level of the things you eat. Half grass and half cow would be 2.5. Humans are around 2.2 [1], because we are omnivores. > at the zooplankton level you already have whales eating it. Well, blue whales are krill specialists and yes have a fairly low trophic level - 3.2 - but it is a cherrypicked example of course. The equivalent is saying an African elephant is a browsing herbivore and generally aren't bothered by predators, which is one less trophic level than the whale example. In reality, both can be preyed upon especially when young or infirm or old [2] and in practice it may be better to not cherrypick. > What's the difference? The difference is in the pelagic ecosystem there are often more levels. The difference is due to trophic efficiency, energy gets moved from primary productivity up the chain faster and with less loss. >but not because algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator No, that's exactly why. Extending Briand and Cohen (1987), we reconsidered which
class of ecosystems supports the longest food chains. Among
all 113 food webs of Briand and Cohen (Briand and Cohen
1987; Cohen et al. 1990), and also among the 28 webs in
three-dimensional habitats, ecosystems with one-celled plant
producers have the longest maximum food chains. By “pelagic” ecosystems, we here mean those based on single-celled
primary producers (phytoplankton).
Among these 113 food webs, the 10 ecosystems with longest maximal chains all had single-celled (phytoplankton)
primary producers (fig. 1A). Of the 28 three-dimensional
webs, the 16 webs with the longest food chains also had
single-celled (phytoplankton) primary producers (fig. 1B).
In all, about half (56) of the 113 Briand and Cohen webs
and 21 of the 28 three-dimensional webs were supported
by single-celled plants.
The 10 webs with longest food chains were all aquatic:
eight were from pelagic three-dimensional ecosystems (six
in oceans and two in lakes) [3] You may have misinterpreted the study from the abstract but full pdf available from googling the name. [1] https://www.pnas.org/doi/10.1073/pnas.1305827110
[2] https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.12906
[3] https://www.journals.uchicago.edu/doi/full/10.1086/686880 |