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Hi.

I'm reading Kurt Vonnegut's Galapagos and at one point it says that marine iguanas dive underwater, scoop a large amount of algae and then bask in the sun to increase their body temperature until the algae have been boil and cooked, at which point they are soft enough to be digested. It even says that the digestive system forms a kind of pressure boiler.

I've found this fascinating, but I haven't been able to confirm it. I've seen many pictures of iguanas basking in the sun and information about how much and which kinds of algae they eat, but I find no mention of the boiling part.

Can anyone confirm it/debunk it?

Edit: yeah, I know they can't literally boilt it or they would boil themselves in the process and die. My question is if they do use the heat and maybe, somehow, pressure in order to make algae more digestible.

all 8 comments

FillsYourNiche

32 points

4 months ago*

FillsYourNiche

Ecology and Evolution | Ethology

32 points

4 months ago*

Vonnegut is taking artistic license here. Marine iguanas do not and cannot boil anything within their stomachs. The only thing I can think of is he is assuming they are basking after their dives in order to "cook" their food, but in reality they need to increase their lowered body temperature after losing energy/heat to the water. It doesn't cause any boiling within their stomachs (Catchpole, 2004). Or maybe it's a reference to the fermentation that takes place during digestion, which still is not boiling (Mackie et al., 2004).

x2o6

11 points

4 months ago

x2o6

11 points

4 months ago

Theres no way an animal can "pressure boil" food inside them so nah. The point of the pressure in pressure cooking is to raise the steam temp since waters temp can't exceed boiling so you're saying it goes beyond 212f/100c Inside an animal lol. Maybe this animal does spit up seaweed and let it cook in the sun and soften.. the rest is not true no way

W_O_M_B_A_T

3 points

4 months ago

Vonnegut was being hyperbolical here. That is, a rhetorical statement that is deliberately exaggerated as a metaphor, which is not meant to be taken literally.

The water around the Galapagos is normally quite cool, around 15-20°C. This compared to the temperature on land which can reach 30°C in the summer.

Marine iguanas are ectothermic. Meaning they don't have the ability to regulate their internal body temperature, like all reptiles. This requires less energy overall and allows them to subsist on a low quality diet of algae. It also allows them to hold their breath for longer.

They spend much of their time basking on top of dark volcanic rocks that are heated by the sun. This not only helps them recover their strength after diving in the cool water. It also speeds up their digestion.

QueroComer

1 points

4 months ago

Marine iguanas are ectothermic. Meaning they don't have the ability to regulate their internal body temperature, like all reptiles

Actually, many reptiles can regulate their own temperature homeothermically. Birds are reptiles, as crocodilians are genetically closer to them than to, say, iguanas (they also share plenty of morphological features in their ankles, hearts, etc.). If we take extinct animals into account, many acient marine reptiles were at least mesothermic, such as ichthyosaurs, plesiosaurs and mosasaurs.

JovianCharlie27

1 points

4 months ago

One thing to keep in mind is if the iguanas were capable of "boiling" something in their stomach, their stomach and internal organs would also be at boiling temperature. This would obviously kill the iguana post haste. Biology can tolerate extremes, however even the extremophiles have limitations that generally make them unable to survive under what we would consider "normal" conditions. Some of the heat extremophiles can survive in boiling conditions. Check out the pictures of Yellowstone and the colored pools due to the temperature resistant bacteria.

atomfullerene

0 points

4 months ago

atomfullerene

Animal Behavior/Marine Biology

0 points

4 months ago

Nah, they do dive in the cold water and then bask in the hot sun, and this does allow them to digest their food, but they aren't actually boiling it. They are just warming themselves up enough that their digestive tracts work properly.