Volvox videos by Shigeru Gougi

Shigeru Gougi (@sgougi on Twitter) has a YouTube channel of video microscopy, including several videos of Volvox:

There’s a good mix of developmental stages here: juveniles (smaller spheroids with nothing visible inside), reproductive age asexual colonies (larger spheroids with small green dots, which are asexual reproductive cells called gonidia), mature asexual colonies (with small spheroids inside that will eventually “hatch” out to become juveniles), and pregnant females (containing yellowish zygotes that will mature into desiccation-resistant spores). I’m not sure about the species ID, but with such a large number of cells, they’re probably in the section Volvox (sometimes known as Euvolvox): [Read more…]

Jackson Wheat on misunderstanding multicellularity

Jackson Wheat has a new video answering Creation Ministries International’s claims that multicellularity is a problem for evolution. CMI’s strategy seems to be

  1. Bring up a topic in evolutionary biology
  2. Pretend that there haven’t been thousands of scientific papers published on that topic
  3. Make an argument from incredulity as if the question they’re asking hasn’t already been answered

Jackson does a great job tearing down CMI’s assertions one by one.

Waltzing Volvox

I can’t believe I haven’t already blogged about this, but if I have it isn’t turning up in my searches. Ravi Balasubramanian’s preprint about “flocking” behavior in Volvox barberi mentioned that

V[olvox] carteri is capable of using fluid forces created by flagellar beating to form waltzing pairs.

He’s referring to a 2009 paper by Knut Drescher and colleagues in Physical Review Letters. Drescher and colleagues analyzed the physics that cause Volvox colonies to enter a hydrodynamically bound state in which two or more spheroids orbit each other in close proximity:

[Read more…]