Skip to content

Southern Fried Science

Over 15 years of ocean science and conservation online

  • Home
  • About SFS
  • Authors
  • Support SFS

Misunderstood Marine Life # 7 – The Living Fossils

Posted on October 3, 2011October 1, 2011 By Andrew Thaler 3 Comments on Misunderstood Marine Life # 7 – The Living Fossils
Science

Horseshoe Crabs - Andrew David Thaler

Horseshoe Crabs, Coelacanths, Seven-gilled sharks, hagfish. Throughout the oceans there are creatures whose primitive bodies hearken back to earlier days in our evolutionary history. They possess basal characteristics that are more akin to those of the ancestors of our contemporary phyla. Because we can look into these organisms and learn something about our own deep past, we think of them not as modern descendants, but as living fossils, relics of a primeval state.

This is, of course, a misnomer.

Charles Darwin coined the term living fossil in On the Origin of Species while describing platypuses and lungfish:

In fresh water we find some of the most anomalous forms now known in the world, as the Ornithorhynchus and Lepidosiren, which, like fossils, connect to a certain extent orders now widely separated in the natural scale. These anomalous forms may almost be called living fossils; they have endured to the present day, from having inhabited a confined area, and from having thus been exposed to less severe competition.

The idea of a living fossil implies that the organism has persisted unchanged for hundreds of millions of years and are somehow relics of the ancient past. Despite their apparently primitive (and I use primitive in the phylogenetic sense of the world – possessing basal characteristics), so-called living fossils are modern organisms. They have been shaped by natural selection to adapt to their environment. In some cases, they’ve retained basal phenotypes, while, in many cases, these apparently basal characters are actually derived relatively recently.

Hagfish are a prime example of this. While they possess a relatively primitive body plan, and have a long fossil record that shows that they have changed little in 300 million years, they do not represent a primitive vertebrate form, but are rather are highly divergent from the hagfish/vertebrate common ancestor. While studying modern hagfish could give you insight into the ecology and behavior of ancient hagfish, they will not lead you to startling revelations about the ancestor of vertebrates, at least not directly.

And that’s the problem with branding a modern organism a “living fossil”. We can’t assume that because something looks superficially similar to it’s ancient forms, that it is necessarily unchanged into the present day. Evolution happens on many scales, visible (and fossilize-able) phenotypes are only one scale. While “living fossils” are fascinating examples of how successful characteristics can persist over time, they are not perfect windows into deep past.

Share this:

  • Click to share on Bluesky (Opens in new window) Bluesky
  • Click to share on Facebook (Opens in new window) Facebook
  • Click to share on Reddit (Opens in new window) Reddit
  • Click to share on Threads (Opens in new window) Threads
  • Click to share on WhatsApp (Opens in new window) WhatsApp
  • Click to share on Mastodon (Opens in new window) Mastodon

Related

Tags: darwin hagfish horseshoe crab living fossils phenotype

Post navigation

❮ Previous Post: Welcome to a Week of Ocean Pseudoscience!
Next Post: 10 misrepresentations about climate change ❯

You may also like

Popular Culture
Five more marine organisms that put their superhero counterparts to shame
April 17, 2013
Weekly Salvage
Hagfish, chill Puffins, swamp monsters, the mining boat floats, and more! Monday Morning Salvage: April 2, 2018
April 2, 2018
Weekly Salvage
HAGFISH! Also deep-sea mining, climate change, The Ocean Cleanup, and more! Monday Morning Salvage: July 17, 2017
July 17, 2017
Weekly Salvage
Cinnamon-flavored hagfish, how to open a coconut, hunted by sperm whales, speaking up for the blue, and more! Monday Morning Salvage: June 11, 2018.
June 11, 2018

3 thoughts on “Misunderstood Marine Life # 7 – The Living Fossils”

  1. WhySharksMatter says:
    October 3, 2011 at 9:59 am

    Why did you take a picture of horseshoe crabs mating? Perv.

  2. Michael Bok says:
    October 3, 2011 at 1:39 pm

    This is a major pet peeve of mine, akin to “highly evolved”, that I hear all the time from scientists. Not only are these phrases conceptually stupid, but they also give creationists something to harp on.

  3. Southern Fried Scientist says:
    October 3, 2011 at 1:40 pm

    Because one of those horseshoe crabs is really confused.

Comments are closed.

Recent Popular Posts

David Attenborough's Ocean is on Hulu and Disney+. Let's watch together and discuss it!David Attenborough's Ocean is on Hulu and Disney+. Let's watch together and discuss it!June 16, 2025David Shiffman
Marine Biology Career AdviceMarine Biology Career AdviceMay 30, 2025David Shiffman
The story of the pride flag made from NASA imagery: Bluesky's most-liked imageThe story of the pride flag made from NASA imagery: Bluesky's most-liked imageSeptember 27, 2024David Shiffman
Shark of Darkness: Wrath of Submarine is a fake documentaryShark of Darkness: Wrath of Submarine is a fake documentaryAugust 10, 2014Michelle Jewell
How many nuclear weapons are at the bottom of the sea. An (almost certainly incomplete) census of broken arrows over water.How many nuclear weapons are at the bottom of the sea. An (almost certainly incomplete) census of broken arrows over water.July 26, 2018Andrew Thaler
Here's what I teach my students about finding jobs in marine biology and conservationHere's what I teach my students about finding jobs in marine biology and conservationApril 10, 2024David Shiffman
What is a Sand Shark?What is a Sand Shark?November 12, 2017Chuck Bangley
Our favorite sea monsters – Ningen (#4)Our favorite sea monsters – Ningen (#4)September 7, 2010Andrew Thaler
Megalodon: the New Evidence is a fake documentaryMegalodon: the New Evidence is a fake documentaryAugust 7, 2014David Shiffman
What can the funniest shark memes on the internetz teach us about ocean science and conservation?What can the funniest shark memes on the internetz teach us about ocean science and conservation?November 8, 2013David Shiffman
Subscribe to our RSS Feed for updates whenever new articles are published.

We recommend Feedly for RSS management. It's like Google Reader, except it still exists.

Southern Fried Science

  • Home
  • About SFS
  • Authors
  • Support SFS


If you enjoy Southern Fried Science, consider contributing to our Patreon campaign.

Copyright © 2025 Southern Fried Science.

Theme: Oceanly Premium by ScriptsTown