Xenobiology 4 — Metabolism
This is the fourth of a series of blogs on the subject of alien and monster biology. The first, which covers respiration, can be found here.
Metabolism is “the sum of the physical and chemical processes in an organism by which its material substance is produced,maintained, and destroyed, and by which energy is made available.”
Metabolism includes eating and drinking, which is the main subject I’m going to cover in this blog. All creatures need to eat and drink something.
The type of food which creatures eat affects their shape and size, dentition (the shape and number of their teeth) and also how they spend their time.
Herbivores eat plants. These are generally low calorie and these creatures need to spend a lot of time eating. Whilst some animals such as horses just chew and eat the leaves, ruminants chew, swallow then regurgitate stomach contents to chew and break it down and extract more nutrients from it, literally “chewing the cud.” Cows spend 6–11 hours grazing and 5–9 hours daily ruminating, so there isn’t much time to develop time travel or complex mathematical theories.
This grinding motion, wearing down leaves made of difficult to digest cellulose means that herbivores have evolved with rows of flattened, roughened chewing teeth. This means that they have elongated faces and tongues.
Carnivores have different dentition, with long sharp canines developed for holding prey and large carnassial teeth at the back for tearing flesh. This leads to a much shorter, wider face shape.
Carnivores are by definition hunters. There are very different social structures between solitary hunter such as tigers, or wildcats and animals who hunt in packs. These pack hunters include hyenas, dolphins and even some birds such as Harris hawks. They can have an eating pattern of lots of hunts and small meals or occasional gorging.
With some creatures, teeth are not the important part of the eating. They may not be either necessary or involved. Consider anteaters, elephants and butterflies; all creatures with a proboscis. This can be an elongated nose or snout, in vertebrates such as elephants. In invertebrates like butterflies, the term proboscis applies to tubular mouthparts used for feeding and sucking.
So how does eating shape the lives of creatures ? Face shape is due to the underlying dentition, which in turn is dictated by diet. This affects ability to shape sounds and communicate.
How about time devoted to eating. If a lot of time is spent eating, is that communal? Would spending hours ruminating affect the ability of a species to develop complicated concepts, or would it function as a philosopher’s club where ideas were discussed and ruminated over?
Farming was seen to be a massive leap forward in human evolution, but there are other living things which have adapted to grow their own food. There is a really interesting article about it on the BBC website.
Damselfish can only survive on red algae (like pandas only eating bamboo), so they farm it. They bite other types of algae off the seaweed which grows in their home area, swim to the edge of their farms and spit out the unwanted algae. This means only the easily-digested red algae grows close to their homes.
The yeti crab, which leaves deep in the sea, near warm vents grows bacteria on its furry arms which it eats at a later date.
Ants and beetles both farm fungus; in the case of the beetles they deliberately tunnel under the bark of a tree to introduce fungus which would not grow there otherwise, meaning they have new sources of food.
Ants carry leaves which they chew into mush, cover with faeces and give to the fungus. It then provides fruiting spore which the ants eat. These ants also have a symbiotic relationship with bacteria. The bacteria produce antibiotics which the ants rub onto the fungus to protect it against infections.
Farming allows some organisms to support others within a social structure. This allows society to develop. It frees up individuals within a society (or time for many individuals) to spend time doing things other than hunting for food. This means that this free time can be spent developing rocket drives, planning political coups or conquering other planets.
Eating together, whether after hunting, or with food gathered from farming, socially bonds creatures. This means they are more inclined to work for the common good, or others within their pack or society.
What about supporting and feeding other creatures? There have been bonds between unlikely animals, eg gorillas and cats or elephants and dogs, but these are in captivity. I could find one incident of capuchin monkeys who raised a baby marmoset, but these things are few and far between, but what if they weren’t? Could you create a new social structure where very different creatures support and aid each other.
Hibernation is a state which affects metabolism dramatically. It is characterized by low body temperature, slow breathing and heart rate, and a slow metabolic rate. It allows survival for long periods with reduced energy requirements. This can allow survival in tricky or dangerous circumstances.
Many mammals of different sizes hibernation; in mammals from bears to hedgehogs. Even some tiny insects eg the small tortoiseshell butterfly hibernate under certain circumstances. It is triggered by low external temperature and causes marked changes to the body systems. In hedgehogs this allows the heart rate to fall from around 200 beats per minute to 20 as the rest of the body systems slow to match.
Could natural hibernation be used instead of suspended animation or cryosleep for interstellar transport? It would be a far less energy intensive than most sci-fi sets ups and less prone to malfunction.
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This is the fourth of a series of blog posts, which have been derived from a lecture I gave at Right on Paper, a one day conference of academic talks on various subjects, for speculative fiction writers, held in London on 3rd February 2018.
This talk, was in turn sparked by a conversation in the bar at Nine Worlds, a science fiction and fantasy convention, where I announced that there was a really interesting talk which could be given on Xenobiology and decided I’d better put my money where my mouth was.
I also blog on veterinary matters here.
