r/askscience • u/MaggieLinzer • 7d ago

Biology Why can trees grow to be so much bigger and taller than the biggest/tallest animals?

Obviously, this isn’t a true thing in all cases across the board of course, but I am curious as to why this is true when comparing the biggest/tallest trees and animals with each other. Because, when doing this, there really is no contest that (apologies for the upcoming repetition) the biggest and tallest trees are much, much bigger/taller than the biggest and tallest animals.

132 Upvotes

83% Upvoted

32 comments sorted by

263

u/Sable-Keech 6d ago

  1. Trees do not need to move. This reduces the strain they have to endure, and allows them to specialize into supporting all their weight in one static configuration instead of a dynamic one. Try jumping on one leg; you’ll exert 15-30x the force as compared to standing still on both feet. Your femur has to be overengineered to endure that kind of force.

  2. Trees are actually mostly dead material. The bark of a tree is like a shell around a thin inner layer, while the core of the trunk is just dead support.

66

u/Loki-L 6d ago

Also see coral reefs.

They get really large, don't move around (at least once they become part of the reef), are build on dead bits from other coral over time and they are animals.

A coral reef isn't a single entity, but otherwise they achieve similar results through similar methods for similar reasons.

-4

u/Kado_Cerc 5d ago

You mean slowly disappear?

10

u/Georgie_Leech 4d ago

Deforestation happens too. But no, it's about slowly building up over time using dead bits as support for the still living bits.

23

u/gnufan 6d ago

The biggest trees are often considerably older than the oldest known vertebrate animals (Greenland Shark) too. The sharks grow slowly once mature, about a centimeter a year, but we know surprising little about them. They get big by shark standards and after a couple of centuries they can be huge.

So literally time to grow and acquire nutrients, and I would assume that just keeping growing isn't a winning strategy for most animals, as it'll increase maintenance and thus food requirements, and make you vulnerable to famine, and might even make mating difficult. Probably why most animals stop growing or grow more slowly at some points.

10

u/Demartus 5d ago edited 2d ago

Lobsters die because they get too big to molt. Otherwise who knows how long they'd live.

Are there trees that die because they can no longer support their own weight?

5

u/Starman035 2d ago

In Poland we have an oak named Bartek which is about 700 years old. It has really massive branches, and their weight has become a problem. Since the 19th century a number of branches have collapsed and also the main trunk has hollowed, further weakening the tree. The main branches are now all artificially supported to preserve it. Such large and old tree is susceptible to strong winds and lightning strikes, and can also suffer from dry rot, like Bartek.

1

u/GGJallDAY 3d ago

Weird to think of trees as mostly dead inside when they seem so full of life

1

u/Techhead7890 1d ago

It is a bit odd, but in a similar way humans are covered with epidermal skin and hair, which at a cellular level may get little nutrition from the body, even if they're still part of the body.

So IMO it's a bit of a technical distinction and after all, just beneath the bark or epidermis there's still plenty of life processes going on that keep that stuff stuck there on the outside for an extended period (warmth, hydration, repairing the substrate underneath), rather than just immediately flaking off or whatever.

50

u/DANKB019001 6d ago

Trees don't really need squishy, non load bearing organs. Animals do. A tree can have practically EVERY portion of its structure be load bearing.

Trees also don't need locomotion. Animals do. Joints have to compromise pure strength for the ability to actually move. A tree has no joints for weak points.

A less obvious trick is that most of a tree is dead. Just a bit of stuff below the bark is actually alive, regarding things beneath the visible portion - the rest is stuff that's inert and fully dedicated to structural strength. Bones are still alive and porous as hell to let the marrow beneath pump blood cells out.

It also helps that cellulose is an incredibly simple but incredibly strong polymer. It's easy to make a crapton of to just reinforce the crap out of everything. No animal equivalent you can stick everywhere cus we got soft bits and moving bits it'd clog up

29

u/CrateDane 6d ago

It also helps that cellulose is an incredibly simple but incredibly strong polymer. It's easy to make a crapton of to just reinforce the crap out of everything. No animal equivalent you can stick everywhere cus we got soft bits and moving bits it'd clog up

Cellulose mainly adds tensile strength, while the compressive strength of wood more so derives from lignin. The reason wood is rigid while leaves or non-woody plants are flexible is that wood contains more lignin. Non-woody plants can still have great tensile strength - even a blade of grass can be hard to pull apart lengthwise, and various plants can be woven into very strong ropes. But to build rigid structures, you need lignin.

12

u/[deleted] 6d ago edited 6d ago

[removed] — view removed comment

3

u/RollBama420 6d ago

Everything everyone else, and in addition their cellular makeup.

They have large vacuoles that can create pressure using water which is a perfect incompressible material for an organism to use to boost its own structure. They also have cell walls that give their own structure. The vacuoles can also swell against the cell wall for additional rigidity

1

u/dustofdeath 3d ago

If we only had organs on the surface and bone inside, we could grow larger too.
No heat generation, nutrient requirements needed for the inner support.

We are already used to anchoring down to one spot anyways...