Cooking underwater

Question

How would an omnivorous civilization of merpeople prepare food? Their diet would be like humans', but naturally seafood-centered. They would have typical medieval technology. How would they "fry" or "bake" things like fish without fire? Would they have to eat raw food only?

The only usable thing that comes to my mind are underwater volcanoes, but they aren't that common. Besides, every family would have to have their own. Going to the surface for cooking doesn't seem convenient either.

Answer 1

When I think of seafood-centred diets, the first people who come to mind are the Japanese, who are famous for eating fish raw. If millions of land dwelling people are already eating raw fish, and have been for hundreds if not thousands of years, even with the technology and means of cooking it, then I don't think that it would be a stretch to assume that the mer-people would prepare and eat their food similarly.

As for the lack of hydrothermal vents in the ocean, they aren't as uncommon as you might think, there are ~40,000km of mid-ocean ridges - all divergent oceanic plate boundaries that experience some degree of hydrothermal activity. What is interesting is that they are essentially a continuous system, so you could build your civilization of mer-people around these ridges as if they were roads or travel routes.

Another option is to not have one culture of mer-people, but to make them as diverse as the people on the surface, the earth is covered by far more ocean than it is land, so you can create quite a large number of aqua-cultures. You could have your ridge dwelling mer people that eat hydrothermally cooked food, your nomadic dolphin hunting tribes that follow pods of dolphins like the ancient North American plains people followed Buffalo, who either eat their meat raw, or cook it at the surface (since dolphins live near the surface and in shallower waters anyways), and your sinister rift dwellers that live deep in the dark oceanic rifts and live off of pillaging other tribes.

Answer 2

Very interesting. Cooking was an important thing in our evolution. By essentially moving part of our digestive system outside our bodies, we lost chewing muscles and got more nourishment extraction with a smaller digestive system. Experiments show that people trying to live on raw food like chimps will give up, not finish their day's ration and get sore, tired jaws.

If something like that was formative to mer-folk evolution of tool use and sapience, note that the issue isn't heat or cooking as we normally understand it, but in offloading digestion and improving upon it.

Besides fire, we also have cheese (treatment by enzymes), fermentation, acids or other chemical reactions. Instead of a rumen inside their bodies, they might do essentially the same thing in a jar. They might evolve to live off particular microorganisms and the broken down tissue it leaves behind after some period of action. Imagine if a cow did not have to cart around however many gallons of culture nor expend personal time and effort into chewing its cud. It could lose all that anatomy and energy expenditure from its phenotype.

Finding suitable processes (e.g. to break down woody material) and designing more elaborate processes will open up new food sources at the speed of invention rather than evolution.

Their manner of feeding might be utterly different than ours. But, it had an important role in evolving complex tool use and community cooperation.

If they don't produce milk (not mammals as discussed on the fortification thread) but regurgitate food to feed the young, it would be obvious to domesticate animals that can eat other food sources and get them to regurgitate after breaking it down. Those would evolve into livestock that's built for that purpose and possibly rather different from the wild ancestor. If the original species also feeds its young in this way, it evolves into one that produces crop-milk in bulk, with a similar idea to how dairy cows exaggerate the mechanism already present for feeding others of the same species.

Answer 3

The purpose of cooking is to predigest food

We cook food in order to soften it, to break it down, to make the nutrients more readily available to us and to change the taste. There are other ways to achieve these goals that don't require heat.

Bacterial / fungal breakdown (decay)

We make use of micro-organisms to process food, for example yogurt, cheese, beer and bread. Simple decay will do the same job.

Chemical breakdown (pickling, salting or drying)

Pickled products will slowly break down over time, changing the taste. Stomach acid would do the trick, or concentrated salt water.

Mechanical breakdown

Chopping or mashing food will render nutrients more readily digestible.

Perhaps products could be prepared inside a skin bag or fish bladder to prevent them from dissolving in the sea water.

Answer 4

They might use hydrothermal vents.

By going deep underwater your merfolk might be able to find zones where the magma seeps from the core heating the water around it, or they might dig a little near the bottom to force the magma out at specific places.

It might not be ideal for frying, and you might want to protect your chefs and food from some noxious chemicals, but the heat it provides might be what you need to at least create some sort of oven.

Answer 5

The same way we do

Humans tend to live by shorelines, and make extensive use of the sea, why would merpeople not do the same in reverse? It would make sense for merpeople to live close to the shore, at which point they can do things like:

• Build infrastructure in non-tidal areas
• Use fire
• Acquire the resources to create floating structures so these things can be done further 'in-sea'
• Interact with Humans

Why risk death in extreme pressures hunting for thermal vents, or volcanic regions, or eat things raw, when you can cook them on the nearest beach with stone age tools?

Answer 6

It is perfectly simple to create a fire underwater. One simply needs to create a bubble and have the fire within it. With a suitable pump mechanism, you can get a steady supply of air to feed small flames.

Once you enter into the industrial age, you might get municipal air pipes running through any major settlement, at least for the rich elite. (An air supply would be useful for a variety of household tasks. e.g. inflating blankets for insulation, creating lifting balloons, keeping novelty pets and houseplants alive...)

Answer 7

Closing the food in clay jars and heating it over a hydrothermal vent is fine for a civilization stuck in the middle ages, but if they can advance into the scientific era they can use another trick: supercritical water.

When water is highly heated and compressed (304.1 K and 7.38 MPa), it becomes an amazing solvent, and can support strange effects like having an open flame underwater. Putting food inside a Supercritical Water Reactor would be similar to putting your steak into a blast furnace or the exhaust of a running rocket motor for searing, but the outer surface of such a device would certainly provide a hot spot for cooking.

Answer 8

This strikes me as an opportunity for an interesting cultural aspect of these merpeople.

If they used the hot vents to cook, and these vents are rare, then this turns cooking from a secluded home activity to a communal event and probably becomes a part of their social fabric.

This is similar to how some other (real) cultures, wash their clothes in the local river, as also a time to share gossip since they all gather at the same spot. This social force is so powerful in some places that it caused water aid projects to fail: well meaning volunteers came into villages and set up running water in homes, but the piping fell into disuse because the women were so used to gathering around the central well as part of their social lives, that they reverted back to going to the well because they missed the social interaction.

So rather than the of the scarcity of the vents being a challenge in creating the world, it may be an opportunity to inspire a culture that is unique to the world.

Answer 9

An underwater civilization might toy with magnesium torches, if they could somehow invent those. Wonderpedia Magazine quotes:

It is colder than in the air and oxygen appears in a different form. Under the water, it is almost impossible for fire to survive – but only almost. Underwater torches made of magnesium are the exception. At 1,000ºC, they burn so hot that the water has trouble cooling down the metal. What’s more, magnesium reacts with the water molecules, releasing the oxygen they contain. The result: the torch keeps burning underwater.

There are also calcium flares which do stuff underwater. You could probably cook food with those too. (Phosphorous too?)

Alternative cooking methods might include boiling most things - it would probably be a common custom to hold a mollusc over a vent, much like a marshmallow over a fire?

Pickling certain foods may also be an option.

Answer 10

Adding to what's been said: Merpeople could harvest digestive chemicals from sea creatures or plants. For example, force-feed an anemone way more than it can eat, then get it to expel its stomach contents into a bag. The anemone gets some nutrition, and the merpeople get most of their food back, but with acids and/or enzymes. A land plant example is pineapple, the fresh juice of which is a meat tenderizer (proteinase).

Cooking with heat underwater is problematic compared to above water, because water conducts heat so much better than air. So if your merpeople use chemical heaters for cooking, they would need to isolate them in some kind of insulating container, like a sharkskin bag. Maybe a double-layer bag, with air insulation.

Instead of chemical heat, how about electrical heat? Your merpeople might have studied electric eels, and thereby gained more knowledge of electricity than what medieval people had.

If they have electricity and wires, they could break water into hydrogen and oxygen, and recombine them to make heat. They wouldn't necessarily have to understand what they are doing.

FWIW, sodium metal burns vigorously under water, and it is part of salt, NaCl. But there's the rub, eh? How to extract it, under water?

Answer 11

Hydrothermal Vents are the only things I can think of, without going to the surface or using fire. You might have to remove the idea of them cooking things. No marine animals (that I know of at least) cook their food, so why would merfolk cook theirs? If they are descendant from humans, but have adapted to live in the water, the way they eat/what they eat/how they eat would have to change. Eating things raw is just a fact of marine (and pretty much all) life.

Answer 12

In all reality they'd probably either raw food, or prepare it in a way that does not involve fire, like marinading it. There are enough serious mechanical difficulties of heat-cooking things under water that it's unlikely their evolution and development would stir that way unless they only ever live close to hydrothermal vents.

If they were somehow interested in cooking their food, they could possibly use certain chemicals (I have seen matches that still burn underwater and the smoke bubbles out) and/or double insulated pots (like a pot within a pot with air in between to make sure heat transfer mostly to food and doesn't boil the water around the pot) but it seems like too much trouble to occur naturally (maybe some surface-lovers might do it, to feel like the surface dwellers)

Answer 13

I can think of a few ways that surface-people technology could be adapted to merfolk to enable cooking. For example, they could use lenses to focus light onto rocks or a dark enclosure in order to cook using solar energy, or given appropriate electrical insulation they could make use of an induction heat source (using any number of power generation mechanisms, including solar, tidal/hydroelectric, etc.) which could even just keep a semi-enclosed vessel up to temperature so as to cook in a bain-marie.

If humans never existed and merfolk did indeed evolve a similar digestive system and seared-flesh tastes to real-world humans, they could make use of warm rocks in tidal pools, or have communal use of shared cooking facilities. Also, the truly intrepid could hold their breath long enough to start a fire on the beach.

However, there isn't much of a need for cooking when you have the many splendors of kelp, fresh fish, and plankton, all of which are perfectly edible (and arguably tastier) raw. I would see merfolk cooking as being some cutting-edge gourmand foodie activity, and possibly an extreme sport depending on how it's performed.

Answer 14

They could make a kind of central heating system with isolated heat pipes from vulcano or hydrothermal valve.

Alternatively they can use uranium as a heat source

Finally, it is possible to use the geothermal gradient and just drill a hole deep enough to tap heat of 100˚C. This can be done anywhere, you don't need to be near a vulcano.

Also with the increased pressure, "boiling" (with bubbles of gas being created) is really not needed. Heating to some 100˚C is good enough for cooking.

Answer 15

While it doesn't exactly solve the issue, one thing the merfolk could do, to copy the human art of cooking, is create pockets of air where they could then have fires. This is easily possible if they have a large fabric that can trap air. Go to the surface, open a container to fill with air, close it, and then release the air underneath the fabric. The fabric, as it fills, will balloon up and provide a pocket of air. There are a number of problems, but I could see it being a feasible (expensive) delicacy.

• The pocket should have a controllable way to release the smoke, carbon dioxide, from fires.

• It still couldn't be too far from the surface, because more oxygen would have to added periodically. It makes more sense the larger the pocket of air is. If you have to resupply oxygen after roasting marshmallows, its probably not worth the effort.

• Getting dry fuel to burn will take some preparation before-hand.

Answer 16

There are areas on the ocean floor where magma and hot gases vent out. Maybe food is fried up at locations like that.