A thread about crocodiles

[relaxedmeatball]

I was watching a show with my kids and learned some amazing things about crocodiles. That prompted me to do some further reading. Here’s some facts:

1. Crocodiles exhibit indeterminate growth. In other words, they never stop growing in size.

2. Crocodiles experience no functional declines with age.

3. In fact, they get more physically capable with age.

4. They can routinely live to 80 years old, and some have lived to over 100 years old in captivity. There is a crocodile called “Henry” who is verified as 124 years old. We actually don’t know their true maximum lifespan.

5. Henry is still reproducing at 124 years old. Crocodiles experience no decline in reproductive potential with age. (He supposedly has 10,000 offspring)

6. Their chance of death per year remains constant. For a human, the chance of dying aged 20 is ~0.04%, but the chance of dying at 80 is ~4.00%. 100x higher. But for a crocodile, there is no difference.

7. They seem to be mostly unaffected by cancers, despite living a long time. We are not sure whether that’s because they never form tumours, or because their immune system is extremely effective at removing them. The latter seems to be the supported theory. Researchers tested crocodile serum against human cancer cells, and found literally hundreds of cancer-inhibiting peptides (Crocodylus porosus: a potential source of anticancer molecules - PubMed)

8. Their immune system is incredible, broad-spectrum, and doesn’t worsen with age. In an in vitro test, crocodile serum killed 23/23 different bacteria, including MRSA. For comparison, human serum killed 8/23. They constantly get wounded, deep cuts etc, and they live in swamps filled with bacteria but seem to rapidly clear almost any infection.

9. Obviously they are “cold blooded” and have extremely dynamic metabolisms, which can slow down dramatically. They can enter a hibernation-like state, can survive hypoxia for a long time, and appear to generate very few ROS.

10. They appear to have negligible senescence. We have no idea why or how. They do weird things with DNA repair and telomeres.

11. Random bonus facts: They have incredible eye sight, including night vision. They have wider hearing range than humans, including infrasound (sub-bass). They can detect pressure waves in water. They have a 3,000 psi bite force (humans are ~160 psi). They have stomach acid capable of dissolving hooves, bones and shells. Based on fossils, they haven’t changed in at least 80 million years. At that time, primates didn’t even exist yet. The only mammals were little shrew things.

This must be an absolutely fascinating research area for those interested in longevity science. Obviously they’re not mammals, but they are still a vertebrate animal living by the same “rules” of eukaryotic cells, DNA, transcription and translation, oxidative-based metabolism etc that we are.

[Agetron]

Crocodiles can eat rotten meat and even decaying carcasses because they have incredibly powerful digestive systems with strong acids and enzymes that can break down almost anything, including bone and cartilage. This ability also makes them less susceptible to food poisoning from pathogens and allows them to scavenge for food, as the decay essentially acts as a form of pre-digestion.

They store the dead victims until properly rotten to aid in eatng.

Alligators typically eat living and fresh kills.

[Satchel]

Also! In a previous life i was a croc vet. They have 2 aortas! And the right aorta usually drains into the hepatic portal circulation……therefore inexperienced vets giving a sedative into the right front leg were in for a nasty surprise…1st pass clearance of anesthetics in the liver and the croc was still awake and a bit bitey!

[Beth]

@Satchel

a previous life i was a croc vet

A statement I thought I would go my whole life without hearing!!! Fascinating!!

The only thing I’ve ever heard about crocodiles is when Jane Birkin requested her name be removed from the Hermes Birkin bag due to their cruel practices.

That incident cured me of any lust I ever had over anything Hermes.

[Nick1]

Isn’t that quite similar to Tortoises?
They both have low metabolic rate so less oxidative stress & cellular damage. They both have immune resilience (tumor suppression and extrinsic microbial threats) and most importantly negligible cellular senescence!
Quite remarkable!
In fact, I wanna say some of the initial caloric restriction hypothesis were in part inspired by Tortoises who eat very little, very intermittent and keep their BMR low.

[BarryAllen]

And then there’s the crocodile museum in Kom Ombo… mummified crocs anyone ?
The Crocodile Museum in Kom Ombo - Inside-Egypt

[relaxedmeatball]

@Agetron

Crocodiles can eat rotten meat and even decaying carcasses because they have incredibly powerful digestive systems with strong acids and enzymes that can break down almost anything, including bone and cartilage. This ability also makes them less susceptible to food poisoning from pathogens and allows them to scavenge for food, as the decay essentially acts as a form of pre-digestion.

Yeah, that’s pretty amazing. But the fact their immune system can fend off so many new bacteria and viruses is incredible. That’s an insane amount of innate immunity, and it doesn’t get worse with age.

What I can’t find is whether they experience any sort of autoimmune disorders. That’s usually the “price” that we humans play for a very reactive immune system. You sorta balance infection and cancer vs autoimmunity.

@Satchel

Also! In a previous life i was a croc vet. They have 2 aortas! And the right aorta usually drains into the hepatic portal circulation……therefore inexperienced vets giving a sedative into the right front leg were in for a nasty surprise…1st pass clearance of anesthetics in the liver and the croc was still awake and a bit bitey!

Haha, that’s so cool! I also read they can close the pulmonary circuit in their heart when they dive, since they don’t need the flow to the lungs. That’s also amazing.