Here’s a website I love:Â http://tolweb.org/
It’s the Tree of Life, scientifically accurate and properly referenced.
I love going through it and discovering the amazing diversity of life on our planet. Going through the Kingdom Animalia, I noticed something though. I had seen a lot of the animals I came across before, either in person, at school, or on the TV, but a lot of the names were totally new to me. They had slipped through the cracks.
And some of them are really awesome, so I thought I might share a few of my favourite under-appreciated branches of the evolutionary tree and make sure no awesome animal is left behind.
Somewhat arbitrarily, let’s start with Bilateria, animals with one line of symmetry down the middle.
Take a look at the above diagram. Reading it from left to right, you’ll notice there are 3 main divisions: Deuterostomia, Ecdysozoa, and Lophotrochozoa. There are also a load of other names with question marks, which means there is no scientific consensus on exactly how those groups are related to others.
Deuterostomia means “two holes” and these are creatures who develop two separate holes (one for eating and one for pooping) early on in their development. Everything with a backbone is a deuterostome and many of these will be familiar to you (except caecilians, since when are those real?) Lophotrochozoa means “crest and wheel animals” and they’re rather complicated, so we’ll leave them for a later post. Ecdysozoa means “to put off” and these creatures moult, shedding their skin as they grow. There’s a lot of underappreciated awesomeness in Ecdysozoa, but here are three of my favourites:
Onychophora (Velvet worms)
Awesome. Just awesome. I’m glad they are nice and small, though, because otherwise I’m not sure I would ever sleep again.
Tardigrada
I’ve already sung the praises of this phylum, but they are just the coolest. The can survive the vacuum and radiation of space, down to -250C, up to 150C, extremely high pressures, extreme dryness, and pretty much anything else we can think up.
In the last couple years they have been getting a bit more attention (they were on the 2015 Royal Institution Christmas Lectures!) But I still think they should be at least as famous as pandas.
Loricifera
These tiny water-dwelling creatures are great, but largely unknown outside the scientific community. Measuring in at less than a millimetre or only a couple hairs thick, they have a band of chitin near their mouths that give them their name as coreslet-bearers.
Loricifera as a phylum was only were discovered in 1983. That’s pretty late considering we’ve been actively searching for new species with tools like microscopes for a few centuries now.
The amazing thing about Loricifera is that they can survive without light or oxygen and are the only multicellular organisms that can claim that. To accomplish this feat, they use alternative cellular machinery. Instead of normal mitochondria, they have hydrogenosomes.
My question is: why did it take a dig through an obscure website built for evolutionary biologists to find out about these weird and wonderful creatures?
When we think of animals, usually it’s the large bony ones that come to mind: mammals, fish, reptiles. But there’s a whole world of invertebrate biology that is considered ‘gross’ and so we generally don’t learn much about it beyond the examples we might find in our gardens. That’s a shame because even the relatively unknown invertebrates I’ve mentioned above are a) really cool and b) super useful.
Understanding onychophoran slime can yield insight into liquids that change into sticky threads and proteins from tardigrades can confer radiation resistance to human cells. Loricifera provide yet another example of ways that complex multicellular life can thrive in extreme environments.
There are loads more amazing animals hiding in the branches of the evolutionary tree, so next time you have a few minutes, go for a climb and see what you find!
Jon Farrow 