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ELI5 Yahaaa

The shift nobody watches

Who Clears Away Dead Animals?

A dead animal in a forest disappears within days, and almost nothing sees it happen.

1 Big scavengersarrive first2 Insects workthrough whatis left3 Microbesfinish the job
A queue that forms within hours, in the same order every time.
  1. Step 1 of 5

    A body is a pile of good food.

    12 counters Starting total ÷ 4 GROUP 1 GROUP 2 GROUP 3 GROUP 4 4 equal groups · 3 in each

    Everything in a living animal — meat, fat, bone — is worth eating. Leaving it untouched would waste a large amount of the energy in a whole ecosystem.

  2. Step 2 of 5

    The big scavengers come first.

    Finding it By soaring, and bywatching each otherOpening it Skin is the hard part

    Vultures, foxes and crows find a carcass within hours, mostly by watching each other. They take the easiest meat, and in doing so open it up for everything smaller.

  3. Step 3 of 5

    Then the insects work through it.

    First arrivals within hours A differentset after afew days Others again after a week Only boneleft

    Beetles and fly larvae arrive in a predictable order, each species turning up at a particular stage. The order is reliable enough to be used as a clock.

  4. Step 4 of 5

    Microbes finish everything.

    Bacteria andfungi break therest down Nutrients takenup by roots

    What no animal takes is broken down by bacteria and fungi into simple substances that soak into the soil. Nothing is left that a plant cannot use.

  5. Step 5 of 5

    Skipping the queue causes real problems.

    The clearing-up shiftCarcasses gone in hoursOr left for weeks, spreading disease

    Where vultures have disappeared, carcasses sit for far longer, feral dogs multiply on them and disease rises. The clearing-up is not optional.

    Forensic scientists use the insect order to estimate how long something has been dead, sometimes to within a day.

The short version

Scavengers, insects and microbes take a dead animal apart in a reliable order, returning everything in it to the soil.

Try it yourself

Leave a fallen apple in a corner of the garden and look at it each day. The same queue forms, more slowly.

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