Now thinking about starting up a dairy spider farm on the prairies of Minnesota


There are these weird salticid spiders that have evolved a radically different morphology — they live in ant nests, and physically mimic the ants. Look at this ant-spider. Isn’t this amazing enough?

That’s a spider? Yeah, count the legs. It’s trying so hard to fit in with tunnel-dwelling insects with three body segments, you just have to applaud the effort.

What’s more, they’ve acquired another evolutionary novelty: they secrete ‘milk’ to feed their young, and have extended parental care. The necessity of milk production was tested with the cruel experiment of painting over the epigastric furrow (the site of secretion) with White-Out, and what happened? All the spiderlings starved to death. The utter bastards. There are things you can get away with when working with invertebrates that you couldn’t do with cute fuzzies with bones. Try doing that experiment with bunnies, just be prepared for torches and pitchforks.

There’s another revelation in this figure caption.

Spider milk and its secretion site in Toxeus magnus.

(A) Ventral view of mother. (B) Milk droplets secreted after slight finger pressure on abdomen.

Did you get that? They are milking spiders. I come from a long line of Norwegian dairy farmers in Minnesota, so you can guess where my mind went from here. Can I get state and federal subsidies for my spider farm? I’ll have to look into it.

The study is primarily about the life history of this spider species, with some experimental manipulation, and it does a thorough job of that.

T. magnus offspring body length growth and food resources during development.
(A) Egg hatching. (B) Absolute milk dependence: Spiderlings do not leave the nest, and the mother releases milk droplets to the nest internal surface. (C) Spiderlings forage during the day and suck milk at night. (D) Subadults nutritionally independent but still return to nest. (E) Spiderlings reach sexual maturity, but some stay with the mother. *The mother. N = 207 offspring, Nnest = 19 surveyed nests, error bars (SEM).

It’s missing one thing, though: any analysis of the chemical make-up of spider milk. I’m going to take a wild guess that unlike mammal milk, which is rich in fats and carbohydrates, spider milk is going to be more like a protein shake — that it’s going to be in many ways similar in composition to the dissolved bug guts that spider adults live on, to simplify the transition from an independent hunting spiderling to a spiderling with an obligate dependency on parental care. Which means a) humans can probably synthesize it by homogenizing masses of fruit flies in a blender with some digestive enzymes, and filtering out the chitin, and b) there’s not going to be much of a human market for it. Alternatively, they suggest that spider milk may have evolved from the breakdown of trophic eggs — that is, eggs produced that do not develop, but provide a food source for other members of the brood. In that case, it may be a soup of phospholipoglycoproteins, similar to the vitellogenins of other arthropods, and its closest vertebrate analog would be egg yolks.

Inquiring minds want to know. They’re going to have to milk a lot of spiders to get enough to analyze, though!


Chen Z, Corlett RT, et al. (2018) Prolonged milk provisioning in a jumping spider. Science 362(6418):1052-1055. DOI: 10.1126/science.aat3692

P.S. There is a Minnesota milk song. They might have to change some of the hand gestures.

Comments

  1. prostheticconscience says

    You might not think there would be much of a human market for homogenized and filtered insects, but then you’d search for “kangfuxin ye” and wonder at humanity.

  2. Matthew Herron says

    …there’s not going to be much of a human market for it.

    I don’t know, it could be the next superfood fad.

  3. davidc1 says

    You are an utter ratbag for not warning us about the photo ,having got that out of the way .
    Well bugger me ,isn’t nature amazing .
    A bit late for the Goop xmas catalogue ,watch out for it next year .

  4. Becca Stareyes says

    I’m planning a Dungeons and Dragons game, and now I really want to have giant dairy spiders running around in my fantasy world. (If we say ‘spider milk’ is like egg yolk, that’s a perfectly sensible thing for other species to want to eat.)

  5. monad says

    The article actually does give the general composition of the milk. It’s very much like you guessed: Spider milk total sugar content was 2.0 mg/ml, total fat 5.3 mg/ml, and total protein 123.9 mg/ml, with the protein content around four times that of cow’s milk.

  6. komarov says

    Which means a) humans can probably synthesize it by homogenizing masses of fruit flies in a blender with some digestive enzymes, and filtering out the chitin, and b) there’s not going to be much of a human market for it.

    When there is no marketing for something you simply (mis)apply marketing and get disgustingly rich by selling crap noone needs. Consider, for example, the possibilities of a product labelled “homeopathic arachnid-lactate”.
    – It’s homeopathic so misusing sciency words and names like “lactate” is almost obligatory
    – The homeopathy bit also means you can get away with producing tiny amounts of actual “lactate”, so it’ll be cheap
    – It can be marketed as “all-natural” to side-stip the synthesis-issue (which discourages potential competitors). At the same time this should give your product another boost on the market. Buzzwords abound!

    I’m willing to accept a smaller cut of the enterprise. Just contact my lawyer when you start setting up your spider dairy* farm. One condition is that I do not have to do any spider milking myself.

    *How about spider yoghurt? How many products in that market can boast any percentage of spider milk? It’ll set you apart from the competition in an instance. (Low-fat, high-spider!)

  7. davidnangle says

    If your homeopathic arachnid-lactate takes off, I can make a mint selling virtually anything else guaranteed 99% free of homeopathic arachnid-lactate. Market size is every human bothered by spider tits.

  8. says

    I spent my post-doc looking at mammalian Oocyte transport/cell volume regulation and DNA methylation… a quick back of the page calculation suggests that the droplet of ‘milk’ (~250 um diameter) is similar to the volume of a mouse oocyte (~100 um). We were able to collect samples of about 50-100 oocytes and do decent protein/DNA work with them (admittedly, the DNA work was easier… exponential growth makes things easy).
    It may be easier than you think to nail down the answer to this question. grab ~50 spider eggs, run a basic protein/DNA fingerprinting assay. Then take ~50 droplets of ‘milk’ and see if they match (I realize I’m exaggerating here… but do spider eggs have an equivalent for ZP proteins?… surely digested eggs would have some trace of those proteins present). Rinse, repeat, ensure your numbers have statistical significance. Profit (somehow).

  9. larpar says

    How many teats do spiders have? I want to get my patent application, for a spider milking machine, in right away.

  10. unclefrogy says

    well alternative sources of food are a thing as is efficiency. might be a cheaper source of high quality of protein than standard feed lot production of meat.
    there also might be a use of a clean “fresh” source of chitin in usable volumes that could replace synthetic plastics.
    The needed input are gourmet chefs for the elite market and snack food manufacturers for impulse purchases at places like 7/11 and liquor stores.
    could not be worse than that sweet dry greasy “hot” pepperoni sticks in shrink wrap plastic at the gas station.
    uncle frogy

  11. Holms says

    …that it’s going to be in many ways similar in composition to the dissolved bug guts that spider adults live on, to simplify the transition from an independent hunting spiderling to a spiderling with an obligate dependency on parental care.

    Pretty sure these are the wrong way around, or these spiders are weirder than you let on.

  12. says

    I’m referring to their evolutionary history. Ancestors would have had independent spiderlings; forms relying on parental care are derived.

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