Was Sponge Bob a Late Bloomer? (Earth, evolution, science, Article)

[Jayhawker Soule]

The article The First Animal On Earth Was Significantly More Complex Than Previously Believed is worth reading if only for the following:

While cautioning that additional studies should be conducted to corroborate his team's findings, Dunn says that the comb jelly could only have achieved its apparent seniority over the simpler sponge via one of two new evolutionary scenarios:

1. the comb jelly evolved its complexity independently of other animals, after it branched off onto its own evolutionary path; or
2. the sponge evolved its simple form from more complex creatures -- a possibility that underscores the fact that "evolution is not necessarily just a march towards increased complexity," says Dunn. "This scenario would provide a particularly dramatic example of that principle."

[painted wolf]

I have to say that I find this new genetic study wicked cool! (if wicked cool isn't a scientifically valid discription it should be)

I cant wait to read this paper when it comes into the university Library. I heard about a preliminary study that suggested this idea. The biggest issue was that they didn't use enough sponge and ctenophores (comb jelly) spcies and genes to make it a fully effective study. The new paper should help clear up some of those issues.

I find the idea of early metazoans (animals) being more complex than we thought to be very appealing. The issue of Ctenophores becoming more complex indipendantly of the rest of the animals while the Poriferans (Sponges) becoming secondarily simple are going to keep things interesting for a while yet.

I'm just glad I was able to take an Invertebreate Zoology course prior to this. I have a lot more apreciation and understanding of the impact than I would have previously. (Not to mention knowing the vocabulary and concepts involved)

I'm willing to go with option #1 for right now... I may however have to reconsider after reading the paper.

wa:do

[Jayhawker Soule]

Originally Posted by painted wolf

I'm willing to go with option #1 for right now... I may however have to reconsider after reading the paper.

wa:do

I tend toward option #2 but, sadly, it's an uninformed bias.

[painted wolf]

Its not an unheard of process for a 'complex' organism to become more 'simple' in its evolutionary development. Just look at all the parasites that have free living cousins.

I must admit I have a bias for #1 and its simply that, a bias. I find the idea of pushing a complex metazoan ancestor back prior to the split between Sponges and comb jellies at the moment a bit tricky to put my head fully around.
I personally find the idea of complexity being convergent in the two groups to be more personally appealing. (it's a terrible bias at the moment. I won't be surprised if I'm wrong, but that is part of the fun with science isn't it. )

Sponges are so extremely simplified that you could put one in a blender, hit frappe and it would simply put itself back together again.
Comb Jellies, on the other hand, are so convergent with 'Jellies' (Cniderians) that its no wonder that they were grouped as a sister phylum.

I really could teach a remedial lesson on the weirdness that is the basal metazoan phyla. Jellyfish alone are some of the strangest creatures out there. (Most of the creatures you may think of when you hear the word 'jellyfish' aren't actual jellyfish, just to add to the oddity of the group.)

wa:do

[Halcyon]

Originally Posted by painted wolf

Sponges are so extremely simplified that you could put one in a blender, hit frappe and it would simply put itself back together again.

Isn't that because a sponge is actually a colony of single cell organisms, differenciated to perform certain tasks, rather than a single organism?

[painted wolf]

you might be tempted by the extremely unspecialized nature of a sponge to think that. Sponges are complete organisms as shown by embryonic development and the fact that they have active immune responses to invasive materials.

Just makes the sponges and the placozoans (an even simpler creature if you can imagine it) all the more interesting.

wa:do

[Halcyon]

Originally Posted by painted wolf

you might be tempted by the extremely unspecialized nature of a sponge to think that. Sponges are complete organisms as shown by embryonic development and the fact that they have active immune responses to invasive materials.

Just makes the sponges and the placozoans (an even simpler creature if you can imagine it) all the more interesting.

wa:do

Hmmm, is this open to debate or has it been recently determined they are a single organism?
I ask because I was taught at uni they were a living example of the stage between single and multi-cellular life, kind like a volvox.

[painted wolf]

Studies have been done to show that the sponge is indeed a single organism and is fully capable of determining the presence of invading tissue.
Origin of the metazoan immune system: Identification of the molecules and their functions in sponges1 | Integrative and Comparative Biology | Find Articles at BNET.com

also a sponge can't be a colony of single celled organisms and still be nested within the Metazoa. The genetic study clearly links them into the Metazoans, (less basal than the 'comb-jelly').

So as far as I know there isn't any real debate on the Metazoan nature of the sponge.

wa:do