Wildlife TV

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Zombies! …exploring taxonomy.

on October 31, 2013

One of my personal interests is the taxonomy of living things. Taxonomy is the system whereby we classify organisms and categorise them depending on their relationships with other organisms. It’s a complicated and fragile process and classifications change all the time as new information is discovered by scientists. Living things were once classified by their apparently similar appearances and habits, however, with the advent of genetic research, we can know for sure exactly what is related to what; it’s remarkable to think that we now know that a cow is more closely related to a whale than it is to a horse; taxonomy can be a wonderful study.

So taxonomy allows us to build a picture of how living things are related to each other as well as their ancestry. For example, we can see that humans (Homo sapiens) and chimpanzees (Pan troglodytes) are closely related, we are all in the same Family (Hominidae), but the distance between us and chacma baboons (Papio ursinus) is greater; we are in the same Order (Primates) but different Families. The more taxonomic categories two organisms share, the more closely related they are. The taxonomic categories are ranked by order of specificness, the broadest being Kingdom (for example, categorising a living thing as animal or plant), and the narrowest being Species. The full list of categories, in order, is: Kingdom, Phylum, Class, Order, Family, Genus and Species but a nice mnemonic for remembering them is: “Kings Play Chess On Fine Glass Surfaces”.

As it’s Halloween today, it’s only fitting to mention a few areas of taxonomy that fit the occasion. There are times when trying to taxonomically classify things can throw up some interesting and unusual results, the first (and most ‘Halloweeny’) example is the Zombie Taxon (taxon being a group of organisms). A Zombie Taxon is where an organism, known to be extinct, reappears in a much later fossil record. This gives the impression that the organism rose from the dead to walk the Earth before dying once more but the truth is less fantastical; usually that geological processes have moved a fossil from one location to another, from older rocks to newer rocks.

Even more interesting is a Lazarus Taxon, where organisms that have been thought to be extinct turn out to still be alive! This has happened many times much to the astonishment of naturalists and scientists and is wonderfully explained at Biodiversity Revolution. It is astonishing that creatures long forgotten can rise from the dead (as did Lazarus in mythology) … however, it’s important to remember that they were never actually gone, we just hadn’t observed them. The hugely diverse habitats of Africa are doubtless home to many species that are yet to be discovered, or rediscovered; who knows what wonders we’ll find.

Picture of a model of a coelacanth, an example of a Lazarus taxon.

The Coelacanth is the most famous example of a Lazarus Taxon; a fish that was thought to have become extinct 65 million years ago was rediscovered by fishermen in 1938.

An Elvis Taxon is where organisms that have been thought to be extinct, reappear later on (mirroring the supposed posthumous sightings of Elvis Presley). Disappointingly there is nothing spooky going on here but rather examples of something called ‘convergent evolution‘. Sometimes organisms that are completely unrelated evolve remarkably similar strategies for survival in similar conditions that make them seem related. A good example of this is termites (Order: Blattodea) and ants (Order: Hymenoptera) which are quite distantly related animals and yet, on the surface, seem to behave in almost identical ways. Sometimes palaeontologists find fossils of two organisms that appear related even though they are separated by huge amounts of time, but it is later revealed that they are just examples of convergent evolution.

There is of course plenty more to talk about with regards to taxonomy but I hope you’re happy that we managed to post an article on Halloween with the ‘zombie‘ in it! Happy Halloween!

Much love,

-Nick

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One response to “Zombies! …exploring taxonomy.

  1. Alison Jobling says:

    I’ve never heard of an Elvis taxon – do they spend their time flipping burgers in a small town in Iowa? 😉 (Sorry, couldn’t resist – that’s what so many supposed sightings have Elvis doing, after all).

    And thanks for the pingback. 🙂

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