Wednesday, May 25, 2011

Freshwater Ecology 1: Back to the Basics

It's been a while since I've updated. Between two weddings, a funeral, and academic concerns my time has been in high demand; though I've managed to carve out a little time for myself here and there I've been so exhausted that any productive work with Nereus seemed like a chore. With any luck I'll be able to get into a routine with my personal life and can devote more consistent effort to Nereus.

The two latest species are the first of the group representing freshwater life. Because they represent the foundation of an ecosystem, they are quite simple species, relatively speaking. Also, because they are such primitive nereids it meant I had to revisit clades that have escaped my attention for some time. I'm discovering what a shambles much of my project is in, and will probably do some taxonomic reorganization once I finish this group.

The pearl worm is a very primitive life form, which means it provided familiar challenges for me but at a somewhat amplified level. First off, I wanted to make sure it fit within the evolutionary framework of the planet, and because it's phylogeny is so very different from every other wormlike species I've done so far it required a whole new taxonomic class. I basically had to build this creature from scratch, making sure that not only did it work as a species on its own but that it had a place in evolution; you be the judge of whether I was successful or not. Also, since I don't like to have a whole class with only one example if I can help it, this means I should probably come up with a few close cousins for this guy.

Secondly, I wanted to make sure it was in fact primitive. While I understand the appeal of superpredators and monsters of prehistoric proportions, I really appreciate seeing some of the more basic species as well. To me, it shows just how in-depth the project really is and helps me see the "big picture" of the world. I like to show that same attention to detail in my own work, and I hope I've done so with the pearl worm.

Finally, and as I've said before, I always want my nereids to be interesting. Making a worm-like critter that has little visual or conceptual difference from an earthworm just doesn't seem worth my time. The swelling yellow tissue was something I thought would really make the pearl worm iconic, and figuring out how it serves the creature that much more fun. I hope it's fun for you too.

The other species I'll talk about here is the river limpet. I must confess a common mistake of mine: that of confusing a limpet with a chiton. I don't know why I always mix the two up, but as a result you may notice that the river limpet has some chiton-like traits. Luckily, when working with aliens I can make such "mistakes," blending traits from different species to make a single unique creature. I considered changing the name to "river chiton," but it didn't seem to have the same ring. Instead I added some physical traits from the limpet to make it so that fictional xenobiologists can make the choice.

At the same time, of course, the river limpet must be uniquely nereid in nature. It has inherited the nested shells, limbs, and motipalps from mollipod ancestors, and while all have specialized, duplicated, and/or atrophied, its heritage should be apparent. I decided to show this species from the underside not only to show how the limbs function as mouthparts in this clade, but I'd never shown the underneath of a mollipod and I thought it would reveal a lot about their phylogeny to do so. Have fun seeing a little critter's underbelly!


  1. Rodlox here, to say this:

    Glad to know you're okay (and sorry about your loss)

    My thought on the River Limpet - I know you said you wanted it to be unchanged and ancient...but the way you've built it, the River Limpets could have an amphibious/terrestrial member of the family somewhere.

    My thought on the Pearl Worm - given how you said its reallllly generalized and simple, you might not want to fill its little group with lots of other species - unless you make some like leeches (blooddrinking) or supergiant sized or living in Nereid intestines...

    ...or they are close relatives of the Lumberjack.

    as always, these are just my 2 cents. your choices rule.

  2. Indeed, just because river limpets are an ancient species doesn't mean that they couldn't have more innovative, specialized cousins. I'll keep your suggestion for an amphibious or terrestrial cousin in mind.

    I don't think "lots of other species" will be added to order Brevia, just one or two so I can show a little bit of branching. I know I said "close cousins," but I really meant "within the same order," or "closer than the lumberjack, strip ribbon, or wermaw." At this point I don't know exactly what that relative will be, so we'll see what my feeble mind comes up with. ;)

    Oh, and thank you for the condolences. It was a lovely service.

  3. I wasn't sure how to convey both congratulations (on the wedding) and condolences (on the funeral) in one sentance, so I erred on the side of loss.

    just my hunch, but I think the lumberjack and the pearl are closer relatives than either is to the wermaw - unless paralel evolution is tricking me again.


  4. I think that's true. Given that the lumberjack and the pearl worm are both long, segmented organisms and wermites are small individuals that have to work together to effect the same behavior, the first two are most likely the closer related of the group. Unfortunately we can't do genetic tests to prove or disprove the hypothesis. ;)