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Oceans as an ecosystem are fascinating. This is simplified but on land the food chain is usually something like Plant-Herbivore-Predator but in the ocean the fo

Oceans as an ecosystem are fascinating. This is simplified but on land the food chain is usually something like Plant-Herbivore-Predator but in the ocean the food chain is much longer, algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator. There's so much opportunities in the predator niche in the oceans that land animals keep going back to the ocean, because the evolutionary challenges were regularly worth it. This truly is a blue planet.

HPsquared 4y ago
I suppose in economic terms there is a lot of "liquidity" (pardon the pun). Species can move around very freely and find their ideal niche.
- deepsun 4y ago
  I can argue the other way. When I dived in different oceans, I was surprised to see the same fish (most popular ones). It's hard to imagine the same on land. Finding a niche is much easier on land, especially in mountains.
  - cwkoss 4y ago
    Oceans are like very deep markets - lots of participants but harder to outcompete the others. SPY is like the pacific - interacting with many other markets, constant yet chaotic. Mountains are like smaller caps - there is a lot more alpha, higher volatility but opportunity size is only a fraction. Would be cool to make a procedural rendering of the financial markets as a landscape/globe map. "Got a cold front blowing across the tech sector today"
  - mrtweetyhack 4y ago
    that's hardly a fair comparison. land is separated by waters that cannot be traversed. Oceans are not separated by land so seeing a particular fish in different oceans does not seem too odd.
    - deepsun 4y ago
      Exactly, that's what I'm talking about. It's much easier to take a niche on land than ocean.
  - djtango 4y ago
    Aren't rats the equivalent of that?
    - nairboon 4y ago
      Or humans
canadianfella 4y ago
There is a lot less life in the oceans than you may imagine. “ there is roughly 80 times more biomass on land than in the oceans. ” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016823/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016823/
- swores 4y ago
  That same link says that it's plants that make up the majority of biomass on land, and that "Bar-On et al. (1) estimate that more than 70% of global animal biomass is found in the ocean".
- kuhewa 4y ago
  I'm confident there's a lot more life in the oceans than you are imagining. The majority of animal biomass is in the oceans. the reason for the massive 80x disparity is the study cited by that reference was doing a census based on weight of carbon, and that figure is dominated by largely metabolically inert wood. By biomass, primary producers in the oceans are indeed much lower, but energetic turnover of phytoplankton is very efficient.. imagine that anywhere the water is greenish it is full of photosynthesizers (and everywhere it is crystal clear as well). In terms of biomass of non-plants, note that pelagic fish are so hyperabundant that ships with sonar thought they were the seafloor wikipedia.org/wiki/Deep_scattering_layer
ramesh31 4y ago
>but in the ocean the food chain is much longer, algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator. And some of the algae and the predators even gang up on the zooplankton: https://en.m.wikipedia.org/wiki/Zooxanthellae https://en.m.wikipedia.org/wiki/Zooxanthellae
RcouF1uZ4gsC 4y ago
One of the most awesome experiences was being able to see an Orca in person closeup. It was truly humbling to realize that in all the vastness and diversity of the ocean, this was the apex predator!
- DanCarvajal 4y ago
  Got to see my first whale earlier this year (Gray Whale) and on the way home I kept tying to hype my SO up on the fact that it's a privilege to be alive on this planet at the same time as the largest animals ever (the whales specifically the Blue). Hoping to see some Orcas later this year on a PNW trip.
  - kridsdale1 4y ago
    I did so on a trip to Orcas Island WA this summer! Our boat travelled farther north than Victoria BC (no border at sea) to find them, then we tailed them back south. The pod located some porpoise and hunted them with encirclement and charges. The mom was training her baby and they rammed the prey so hard it flew at least 20 feet in the air. Probably broke all the bones in its body.
- bcrosby95 4y ago
  Another fascinating thing is that, as far as we know, the Blue Whale is the largest animal that has ever existed.
- beachy 4y ago
  We sometimes have pods of orcas hunting stingrays around here. In their urgency to get away, the rays will sometimes hurl themselves up out of the water and onto the rocks. Apparently (though I've never seen it) the orcas will sometimes chase them up onto the rocks.
at_a_remove 4y ago
I think there's room for Corpse-Scavenger subloops in there. After the mother of all extinctions, it would be a field epoch for the scavengers.
- throwaway5752 4y ago
  Nothing that was talked about in the parent post is unique to marine ecosystems, is it? The terrestrial food chains information is just incorrect. Fungi are absent in that description. Insects are eaten by countless prey species, apex predators have multiple trophic levels below them. There are countless insect, fungal, and animal carrion feeders. A post that is so factually inaccurate should not be so upvoted. We shouldn't meta comment, but the rapid decrease in submission and comment quality on Hacker News is really a problem. And the fact that land animals evolve to marine lifestyles is just expected, oceans are more than 70% of Earth's surface. The lack of marine, pelagic animals is notable in that sense.
  - DanCarvajal 4y ago
    Well I did say that I was simplifying somethings, which I think is useful as this is kind of a classic shorthand way of comparing example food chains for the layperson. My goal was to not lose the forest for the trees. Come to think of it, I talk to a lot of five years olds which has definitely impacted how I approach topics.
    - canadianfella 4y ago
      [dead]
    - deleted 4y ago
      [deleted]
    - kuhewa 4y ago
      The replies to your comment were wild to read through, strong vibes of 'how dare you simplify something and retain the essence of a valid point but fail to include this one tangental aspect I thought of'
Lammy 4y ago
We should also thank the Moon for its tidal energy :) “Ages ago, life was born in the primitive sea. Young life forms constantly evolved in order to survive. Some prospered — some did not. All sorts of life ebbed and flowed like the tide. In the quiet rhythm of the mother sea, life grew, always seeking to survive and flourish.”
- olivermarks 4y ago
  Also the phytoplankton in the oceans that process the air we breath. https://www.nationalgeographic.org/activity/save-the-plankton-breathe-freely https://www.nationalgeographic.org/activity/save-the-plankto...
wardedVibe 4y ago
I mean, if you start including insects the tree on land is way deeper. There's more size niches in land photosynthesizers for whatever reason, so there's more variety in herbivore size too.
- kuhewa 4y ago
  Interesting, I don't think it's true on the extremes but I reckon that is true when you think of the abundance of megafaunal herbivores on land, like there's a dugong and a few decent sized fishes, but there's no proliferation of deer, goats, rhino giraffe etc. Not true at the extremes I say because pelagic ecosystems have small single cells handling their primary productivity, you have microscopic copepods starting the grazing at the same size as the smallest herbivorous insects, and until recently you had stellars sea cow weighing in at 8-10 t, more than an African elephant.
culi 4y ago
Interesting, I wouldn't really think the ocean food chain is "more complicated". Soil ecosystems themselves are extremely complex and much more tightly integrated with what's happening above ground than we often realize for example But I do agree there's some really interesting key differences. For one, speciation on land is often driven by geological barriers that split populations apart. But these types of barriers are much less common in the ocean where this only really happens to organisms that are restricted to shallow waters (and even then "island-hopping" happens much more commonly)
- gtvwill 4y ago
  Temperature and depth are your barriers in the ocean. Water can be shallow and swimmable but if it's too cold to live in for a species it may well be a brick wall.
  - kuhewa 4y ago
    But broadly, the distribution of thermal habitat isn't very complex, it varies across a latitudinal cline and at a broad regional scale with ocean currents but your don't have small island-sized patches of warm water for example. Most fine scale anomalies are short lived especially relative to the scales speciation happens over. Depth is a thing and can separate disparate communuties on seamounts like alpine species on mountain tops. The difference is most Maine species have a pelagic larval stage and can disperse widely, so barriers to gene flow are more limited than on land.
- kuhewa 4y ago
  Well, you have the same thing happening in marine sediments as well with interstitial organisms, and really in the water itself you have this still fairly poorly understood food web (see: Marine microbial loop) occuring before your reach a size of familiar organisms. Different terrestrial and marine habitats and assemblages come to mind where one may be more complex than another but overall if the degree of niche partitioning at any given trophic level was a wash between land and sea water, I think marine may take the cake on complexity just due to the webs being longer and thus room for more edges between nodes https://pubmed.ncbi.nlm.nih.gov/27322123/ https://pubmed.ncbi.nlm.nih.gov/27322123/
TheSpiceIsLife 4y ago
You mean fungi / bacteria > bacteriophage / virus > herbivorous insects > predatory insects > plants / fungi > microogranisms more generally > plants / fungi > insects > reptile > birds > plants > birds > insects > reptile / birds > herbiverous mammals > insects <> bird eating spiders > birds > plants > predatory mammals > bacteria / fungi <> viruses ... You're over simplying it because you think the oceans are more complicated or something.
- funnymony 4y ago
  Do fungi exist at sea?
  - kuhewa 4y ago
    Yes
  - oboes 4y ago
    https://en.wikipedia.org/wiki/Marine_fungi https://en.wikipedia.org/wiki/Marine_fungi
- kuhewa 4y ago
  Well, the food chains are indeed longer and support more trophic levels [1], so with the same degree of cycling as you presented there are indeed more opportunities for complexity. [1] https://pubmed.ncbi.nlm.nih.gov/27322123 https://pubmed.ncbi.nlm.nih.gov/27322123
peoplefromibiza 4y ago
> Plant-Herbivore-Predator if you ignore all the non mammal life... and even considering only mammals, that's only a fraction of the food chain for example: boars or rats
- kuhewa 4y ago
  Mammal species can be herbivores or predators though? If you are referencing the existence of omnivores, that's fair, but they'd just kinda sit at a half step between herbivore and predator. Really you'd want to consider not just one type of predator but secondary consumers that eat herbivores, tertiary consumers that eat them, like a snake, and quartenary consumers that eat them, like a hawk. There's a little exaggeration in that comment but directionally it holds true, marine food chains are longer, in part because primary production in pelagic ecosystems is single cell phytoplankton instead of plants, and the small size of things a lot of room for higher trophic levels in terms of energetics. https://pubmed.ncbi.nlm.nih.gov/27322123 https://pubmed.ncbi.nlm.nih.gov/27322123
  - peoplefromibiza 4y ago
    > that's fair, but they'd just kinda sit at a half step between herbivore and predator no it doesn't. We are not predators and are not herbivores. swines are not herbivore but not predators. But in fairness it's not very common, the real point is that if we look at the data, mammals are mostly carnivores, 63% of them is, but that doesn't imply being a predator. The other point is that the cycle is not predator eats herbivore which eats plants. That is a mammal-centric view that completely removes from the equation the majority of lifeforms on Earth, 'cause mammals are a minority of the species in nature. Many predators also feed from other lesser predators, example: snakes. Snakes don't eat herbivores, they eat small rodents that usually eat other smaller animals. Truth is the cycle is a lot more about bacteria that eats a substance (that probably comes from the putrefaction of some dead animal) that creates some other substance that other bacteria live on and they too produce something that simple life forms use to produce energy and after many of these steps, maybe there's some plant or fungi that consumes those nutrients in the soil and then "do you have time to talk about our lords and saviors the insects, the 900 thousands species of them?" 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. > marine food chains are longer a bit longer doesn't mean what the original comments was about. The study also says that the chain is longer in the lowest segment of the chain where the size is microscopic. So when you arrive at the zooplankton level, you are already at very large animal eats helpless food (plants or soup of proteins) and then get eaten by a predator or it's too big to be annoyed by anybody (elephants and whales, for example)
kuhewa 4y ago
I'm not sure what the greatest plausible number of trophic levels is for a single chain of consumption, probably 7 to terrestrial food chain of 5 (grass mouse. But on average food chains aren't that long, marine apex predators sit around trophic level 4.5. There can be an impressive degree of niche partitioning in somd marine habitats though! https://academic.oup.com/icesjms/article/55/3/467/655070 https://academic.oup.com/icesjms/article/55/3/467/655070
agumonkey 4y ago
Is it due to the fact that water unifies the mechanics ? any can "fly" underwater...
devoutsalsa 4y ago
“There’s always a bigger fish.” -Qui-Gon Jinn (and probably a whole bunch of others)

HPsquared 4y ago

I suppose in economic terms there is a lot of "liquidity" (pardon the pun). Species can move around very freely and find their ideal niche.

deepsun 4y ago
I can argue the other way. When I dived in different oceans, I was surprised to see the same fish (most popular ones). It's hard to imagine the same on land. Finding a niche is much easier on land, especially in mountains.
- cwkoss 4y ago
  Oceans are like very deep markets - lots of participants but harder to outcompete the others. SPY is like the pacific - interacting with many other markets, constant yet chaotic. Mountains are like smaller caps - there is a lot more alpha, higher volatility but opportunity size is only a fraction. Would be cool to make a procedural rendering of the financial markets as a landscape/globe map. "Got a cold front blowing across the tech sector today"
- mrtweetyhack 4y ago
  that's hardly a fair comparison. land is separated by waters that cannot be traversed. Oceans are not separated by land so seeing a particular fish in different oceans does not seem too odd.
  - deepsun 4y ago
    Exactly, that's what I'm talking about. It's much easier to take a niche on land than ocean.
- djtango 4y ago
  Aren't rats the equivalent of that?
  - nairboon 4y ago
    Or humans

canadianfella 4y ago

There is a lot less life in the oceans than you may imagine. “ there is roughly 80 times more biomass on land than in the oceans. ” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016823/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016823/

swores 4y ago
That same link says that it's plants that make up the majority of biomass on land, and that "Bar-On et al. (1) estimate that more than 70% of global animal biomass is found in the ocean".
kuhewa 4y ago
I'm confident there's a lot more life in the oceans than you are imagining. The majority of animal biomass is in the oceans. the reason for the massive 80x disparity is the study cited by that reference was doing a census based on weight of carbon, and that figure is dominated by largely metabolically inert wood. By biomass, primary producers in the oceans are indeed much lower, but energetic turnover of phytoplankton is very efficient.. imagine that anywhere the water is greenish it is full of photosynthesizers (and everywhere it is crystal clear as well). In terms of biomass of non-plants, note that pelagic fish are so hyperabundant that ships with sonar thought they were the seafloor wikipedia.org/wiki/Deep_scattering_layer

ramesh31 4y ago

>but in the ocean the food chain is much longer, algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator. And some of the algae and the predators even gang up on the zooplankton: https://en.m.wikipedia.org/wiki/Zooxanthellae https://en.m.wikipedia.org/wiki/Zooxanthellae

RcouF1uZ4gsC 4y ago

One of the most awesome experiences was being able to see an Orca in person closeup. It was truly humbling to realize that in all the vastness and diversity of the ocean, this was the apex predator!

DanCarvajal 4y ago
Got to see my first whale earlier this year (Gray Whale) and on the way home I kept tying to hype my SO up on the fact that it's a privilege to be alive on this planet at the same time as the largest animals ever (the whales specifically the Blue). Hoping to see some Orcas later this year on a PNW trip.
- kridsdale1 4y ago
  I did so on a trip to Orcas Island WA this summer! Our boat travelled farther north than Victoria BC (no border at sea) to find them, then we tailed them back south. The pod located some porpoise and hunted them with encirclement and charges. The mom was training her baby and they rammed the prey so hard it flew at least 20 feet in the air. Probably broke all the bones in its body.
bcrosby95 4y ago
Another fascinating thing is that, as far as we know, the Blue Whale is the largest animal that has ever existed.
beachy 4y ago
We sometimes have pods of orcas hunting stingrays around here. In their urgency to get away, the rays will sometimes hurl themselves up out of the water and onto the rocks. Apparently (though I've never seen it) the orcas will sometimes chase them up onto the rocks.

at_a_remove 4y ago

I think there's room for Corpse-Scavenger subloops in there. After the mother of all extinctions, it would be a field epoch for the scavengers.

throwaway5752 4y ago
Nothing that was talked about in the parent post is unique to marine ecosystems, is it? The terrestrial food chains information is just incorrect. Fungi are absent in that description. Insects are eaten by countless prey species, apex predators have multiple trophic levels below them. There are countless insect, fungal, and animal carrion feeders. A post that is so factually inaccurate should not be so upvoted. We shouldn't meta comment, but the rapid decrease in submission and comment quality on Hacker News is really a problem. And the fact that land animals evolve to marine lifestyles is just expected, oceans are more than 70% of Earth's surface. The lack of marine, pelagic animals is notable in that sense.
- DanCarvajal 4y ago
  Well I did say that I was simplifying somethings, which I think is useful as this is kind of a classic shorthand way of comparing example food chains for the layperson. My goal was to not lose the forest for the trees. Come to think of it, I talk to a lot of five years olds which has definitely impacted how I approach topics.
  - canadianfella 4y ago
    [dead]
  - deleted 4y ago
    [deleted]
  - kuhewa 4y ago
    The replies to your comment were wild to read through, strong vibes of 'how dare you simplify something and retain the essence of a valid point but fail to include this one tangental aspect I thought of'

Lammy 4y ago

We should also thank the Moon for its tidal energy :) “Ages ago, life was born in the primitive sea. Young life forms constantly evolved in order to survive. Some prospered — some did not. All sorts of life ebbed and flowed like the tide. In the quiet rhythm of the mother sea, life grew, always seeking to survive and flourish.”

olivermarks 4y ago
Also the phytoplankton in the oceans that process the air we breath. https://www.nationalgeographic.org/activity/save-the-plankton-breathe-freely https://www.nationalgeographic.org/activity/save-the-plankto...

wardedVibe 4y ago

I mean, if you start including insects the tree on land is way deeper. There's more size niches in land photosynthesizers for whatever reason, so there's more variety in herbivore size too.

kuhewa 4y ago
Interesting, I don't think it's true on the extremes but I reckon that is true when you think of the abundance of megafaunal herbivores on land, like there's a dugong and a few decent sized fishes, but there's no proliferation of deer, goats, rhino giraffe etc. Not true at the extremes I say because pelagic ecosystems have small single cells handling their primary productivity, you have microscopic copepods starting the grazing at the same size as the smallest herbivorous insects, and until recently you had stellars sea cow weighing in at 8-10 t, more than an African elephant.

culi 4y ago

Interesting, I wouldn't really think the ocean food chain is "more complicated". Soil ecosystems themselves are extremely complex and much more tightly integrated with what's happening above ground than we often realize for example But I do agree there's some really interesting key differences. For one, speciation on land is often driven by geological barriers that split populations apart. But these types of barriers are much less common in the ocean where this only really happens to organisms that are restricted to shallow waters (and even then "island-hopping" happens much more commonly)

gtvwill 4y ago
Temperature and depth are your barriers in the ocean. Water can be shallow and swimmable but if it's too cold to live in for a species it may well be a brick wall.
- kuhewa 4y ago
  But broadly, the distribution of thermal habitat isn't very complex, it varies across a latitudinal cline and at a broad regional scale with ocean currents but your don't have small island-sized patches of warm water for example. Most fine scale anomalies are short lived especially relative to the scales speciation happens over. Depth is a thing and can separate disparate communuties on seamounts like alpine species on mountain tops. The difference is most Maine species have a pelagic larval stage and can disperse widely, so barriers to gene flow are more limited than on land.
kuhewa 4y ago
Well, you have the same thing happening in marine sediments as well with interstitial organisms, and really in the water itself you have this still fairly poorly understood food web (see: Marine microbial loop) occuring before your reach a size of familiar organisms. Different terrestrial and marine habitats and assemblages come to mind where one may be more complex than another but overall if the degree of niche partitioning at any given trophic level was a wash between land and sea water, I think marine may take the cake on complexity just due to the webs being longer and thus room for more edges between nodes https://pubmed.ncbi.nlm.nih.gov/27322123/ https://pubmed.ncbi.nlm.nih.gov/27322123/

TheSpiceIsLife 4y ago

You mean fungi / bacteria > bacteriophage / virus > herbivorous insects > predatory insects > plants / fungi > microogranisms more generally > plants / fungi > insects > reptile > birds > plants > birds > insects > reptile / birds > herbiverous mammals > insects <> bird eating spiders > birds > plants > predatory mammals > bacteria / fungi <> viruses ... You're over simplying it because you think the oceans are more complicated or something.

funnymony 4y ago
Do fungi exist at sea?
- kuhewa 4y ago
  Yes
- oboes 4y ago
  https://en.wikipedia.org/wiki/Marine_fungi https://en.wikipedia.org/wiki/Marine_fungi
kuhewa 4y ago
Well, the food chains are indeed longer and support more trophic levels [1], so with the same degree of cycling as you presented there are indeed more opportunities for complexity. [1] https://pubmed.ncbi.nlm.nih.gov/27322123 https://pubmed.ncbi.nlm.nih.gov/27322123

peoplefromibiza 4y ago

> Plant-Herbivore-Predator if you ignore all the non mammal life... and even considering only mammals, that's only a fraction of the food chain for example: boars or rats

kuhewa 4y ago
Mammal species can be herbivores or predators though? If you are referencing the existence of omnivores, that's fair, but they'd just kinda sit at a half step between herbivore and predator. Really you'd want to consider not just one type of predator but secondary consumers that eat herbivores, tertiary consumers that eat them, like a snake, and quartenary consumers that eat them, like a hawk. There's a little exaggeration in that comment but directionally it holds true, marine food chains are longer, in part because primary production in pelagic ecosystems is single cell phytoplankton instead of plants, and the small size of things a lot of room for higher trophic levels in terms of energetics. https://pubmed.ncbi.nlm.nih.gov/27322123 https://pubmed.ncbi.nlm.nih.gov/27322123
- peoplefromibiza 4y ago
  > that's fair, but they'd just kinda sit at a half step between herbivore and predator no it doesn't. We are not predators and are not herbivores. swines are not herbivore but not predators. But in fairness it's not very common, the real point is that if we look at the data, mammals are mostly carnivores, 63% of them is, but that doesn't imply being a predator. The other point is that the cycle is not predator eats herbivore which eats plants. That is a mammal-centric view that completely removes from the equation the majority of lifeforms on Earth, 'cause mammals are a minority of the species in nature. Many predators also feed from other lesser predators, example: snakes. Snakes don't eat herbivores, they eat small rodents that usually eat other smaller animals. Truth is the cycle is a lot more about bacteria that eats a substance (that probably comes from the putrefaction of some dead animal) that creates some other substance that other bacteria live on and they too produce something that simple life forms use to produce energy and after many of these steps, maybe there's some plant or fungi that consumes those nutrients in the soil and then "do you have time to talk about our lords and saviors the insects, the 900 thousands species of them?" 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. > marine food chains are longer a bit longer doesn't mean what the original comments was about. The study also says that the chain is longer in the lowest segment of the chain where the size is microscopic. So when you arrive at the zooplankton level, you are already at very large animal eats helpless food (plants or soup of proteins) and then get eaten by a predator or it's too big to be annoyed by anybody (elephants and whales, for example)

kuhewa 4y ago

I'm not sure what the greatest plausible number of trophic levels is for a single chain of consumption, probably 7 to terrestrial food chain of 5 (grass mouse. But on average food chains aren't that long, marine apex predators sit around trophic level 4.5. There can be an impressive degree of niche partitioning in somd marine habitats though! https://academic.oup.com/icesjms/article/55/3/467/655070 https://academic.oup.com/icesjms/article/55/3/467/655070

agumonkey 4y ago

Is it due to the fact that water unifies the mechanics ? any can "fly" underwater...

devoutsalsa 4y ago

“There’s always a bigger fish.” -Qui-Gon Jinn (and probably a whole bunch of others)