Episode 213 – Decomposers

Listen to Episode 213 on PodBean, YouTube, Spotify, or wherever you listen to your favorite podcasts!

Leave a carcass or a log or a pile of poop out in the wild long enough and it will break down into its component parts. This episode, we discuss the diversity and ecological importance of Decomposers.

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A giant flying squirrel from the Gray Fossil Site

WARNING. This page contains images of decomposing animal remains.

Breaking Down

Any unliving organic material left out in the wild – a carcass, a fallen log, a pile of poop – will gradually break down thanks to the action of organisms and the elements. This process is decomposition. It takes many forms, and there’s plenty of overlap with related concepts like scavenging and digestion.

The most famous decomposers are bacteria and fungi, but plenty of animals contribute to the process as well, including lots of flies and beetles that feed on or utilize carcasses or dead plants. But not all organic material is the same, and neither are all decomposers. For example, some insects specialize on fresh carcasses, while others don’t move in until later in the process, and some species break down soft tissues while others focus on fluids. Meanwhile, certain fungi are among the only organisms that can break down the tough tissues of woody plants. Decomposition takes a community, and indeed, a fallen tree or carcass often becomes home to an entire ecosystem of decomposers.

Decomposers are a crucial part of an ecosystem, since they disassemble organic compounds and make their component parts available to other organisms, either by releasing nutrients into the surrounding environment or by becoming food for other animals.

The process of decomposition tends to follow a consistent set of general stages. Studying these can be important for understanding how a carcass impacts its local environment, and it’s especially useful in fields like forensics where scientists can use this information to determine a time since death.

Decomposers are obviously very important for the fossil record, since most fossil remains have undergone some amount of decomposition. In many cases, well-preserved fossil remains are an indicator of limited decomposition; an insect in amber can be so beautifully preserved because it became inaccessible to decomposers when it became trapped in resin.

On the other hand, some research suggests that the action of certain bacteria or fungi can actually improve fossilization, either by concentrating certain minerals around organic remains or by out-competing more damaging decomposers.

The study of what happens to an organism after it dies and before it becomes a fossil is taphonomy.

Learn More

Decomposition of dinosaur bones (technical, open access)

A Miocene whale fall (technical, open access)
A Jurassic ichthyosaur fall (technical, open access)

Fungus-induced fossilization (technical, open access)

Did the evolution of white rot fungi stop Paleozoic coal formation? (article)
No, it didn’t (technical, open access)

Methods of estimating Time Since Death (technical, open access, also a bit gross)

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If you enjoyed this topic and want more like it, check out these related episodes:

• Episode 30 – Prehistoric Poop
• Episode 173 – Herbivores (Plant-Eaters)
• Episode 200 – Fungi

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