I know the blue whale is the largest known animal to have existed on Earth, but can animals conceivably grow larger, or is that pretty much the largest animal you can expect to find in the universe?
What about dinosaurs? They aren’t on earth now, but they have been and the universe is a big place.
I think the blue whale is probably near the limit for earth creatures. Living in water and having a plentiful food source helps.
Sauropods seemed to also have a plentiful food source but were limited by having to support their own weight and walk around on land.
I suppose an animal on a smaller planet with less gravity can get bigger.
Nothing even remotely close to godzilla though.
In the universe? There could be lifeforms that don’t exist on a planet, that aren’t affected by gravity or dependent on food sources. You expect a factual answer to this?
Dinosaurs, on the whole, aren’t that overly huge. The sauropods were pretty huge, including the largest land animals ever (the high weight estimate* for the largest of them, Argentinosaurus, is about even with a blue whale), but they’re the only ones that are really excessively large. Excluding the sauropods, extinct dinosaurs covered pretty much the same size range as modern land animals (and, of course, extant ones include some tiny little buggers), though, outside the theropods, they tended toward parity with mid-size to large mammals.
- The estimates, based on a really, really incomplete specimen cover a large range…the most likely size is ‘only’ about 3/4 the size of the blue whale.
The sauropods were the biggest, sure, but other groups got pretty big, too. T. rex was bigger than any modern land animal, and much bigger than any modern predator.
In the universe ? Other planets are likely to have different constrains on size. Lower gravity, denser atmosphere, more oxygen…
Gasbag creatures in a gas giants atmosphere could probably get pretty massive. Or colonial organisms. Jellyfish can get pretty big.
There are masses fungi and trees that are part of clonal colonies. Depending on how you define a single animal it’s possible that a massive animal colony could live in the ocean. On land it would be more difficult for a large animal colony to remain intact and still have a food source.
Of course, if we’re looking at other planets (or non-planet environments, for that matter), then the stipulation of “animal” becomes meaningless. That’s one of the categories of life found on Earth, and would have no applicability to alien life. It’d be like debating whether a Pennsylvanian is a Clevelander, Cincinattian, or Columbusite. You can maybe argue that Pittsburgh is the equivalent of Cleveland and Harrisburg is the equivalent of Columbus, but they’re not the same thing.
All true, of course. But, I’d still argue it’s ‘about the same range’…we’re ‘only’ talking about around twice the size of an African elephant for the largest theropods.
I might put a bit too much slack on the range, due to annoyance with the kaiju-level dinos that frequently appear in fiction, though, I admit.
I dunno, “twice the size of an elephant” seems plenty big to me. Especially when you factor in that it’s bipedal, meaning that each leg needs to be able to support two or three times as much weight. And when you consider that it’s a carnivore, and the largest carnivores are usually smaller than the largest herbivores: The largest land carnivore today is only about a half-ton.
The universe? You guys aren’t even bothering to recognize the diversity of life on Earth. Sayeth the BBC:
It continues:
OK, I assume the OP was defining “animal” as ambulatory (or natatory), and having a common root system on a set of clones doesn’t meet that definition. It does, however, point to the difficulties of defining life forms and recognizing whether they are a single organism or not. These difficulties will be multiplied on any alien world. And that’s beyond the simple physics of gravity and buoyancy, which define limitations for ambulatory or natatory creatures.
For both land and marine creatures, the upper limits are largely dependent on oxygen levels. Dinosaurs could become huge because there was about 20% more oxygen in the atmosphere. Oceanic oxygen levels are also variable, and it’s likely that the blue whale represents the upper limit on size based on current levels.
Oh, we’re totally in agreement on that…we’re only disagreeing on boundries of ‘the same range’.
I’d say ‘exactly the size of an elephant’ is pretty darn big, too. And when our comparison includes things that are 10+ times the size of an elephant (and things that are less than 1% the size of one), I think that justifies putting 2X within the same range - though I can see where you’re coming from, too.
I’m curious if there were enormous sea dinosaurs whose bones have never been discovered. If their bones are buried on the ocean floor, they are likely lost to history.
I’ve seen that claim, but it appears to be controversial. A report in Geochimica et Cosmochimica Acta in 2013 says that oxygen levels were 30% to 50% lower during the past 220 million years than they are today. The author says “We do not want to negate the influence of oxygen for the evolution of life in general with our study, but the gigantism of dinosaurs cannot be explained by those theories.”
Blue whales get their oxygen from the air, not from oceanic oxygen, unless my education has been immensely deficient. So, presumably, if oxygen levels are the constraint for whales, then with higher oxygen levels in the past, sea creatures that breathed air could have evolved to be bigger even than blue whales.
But what about the giant insects? I thought they were some of the best proof of higher oxygen in the past, due to limitations on the way they breathe.
You could define an animal in ecological/physiological terms as a macroscopic heterotroph that ingests its food and absorbs it internally.
The terms “animal” and “plant” have undergone radical revision in Biology since the 1960s. Formerly biologists tried to shoehorn all organisms into one category or the other. “Animal” included many heterotrophic protists, while “plant” was considered to include both autotrophs like green algae and cyanobacteria, and heterotrophs such as fungi, and both eucaryotes and procaryotes like bacteria (which were considered a kind of fungi). Now “Animalia” only includes multicellular heterotrophic eucaryotes, and “Plantae” is restricted to multicellular green plants plus green algae. It is recognized that many organisms are neither plants nor animals.
When life is discovered on other planets, we may need to redefine traditional terms, or invent new ones. However, I would think that on many Earth-like planets life forms parallel to animals and plants would occur, and could non-technically be referred to as such.
Extremely unlikely. Marine animals are much more likely to be fossilized than terrestrial ones because depositional environments are much more common in aquatic situations.
The closest thing to an aquatic dinosaur may have been Spinosaurus, one of the largest if not the largest theropods.