Talmudic Question #95

by Barry Goldman

Almost all multicellular critters known (animals, plants, fungi, algae) go through a microbial stage in their life cycle - gamete or spore. Can you think of a multicellular species or higher taxon that has NEVER been caught going through the microbial stage?

Comments

[peter w.]

perhaps the bedelloid rotifers might fit your profile? bdelloid rotifers reproduce by parthenogenesis. oogenesis proceeds via two mitotic divisions. meiosis is absent, and therefore there is no stage during which chromosome reduction occurs; i.e. no haploid stage.

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Some kinds of planaria completely neuter. At least in laboratory Settings.
Planarian separation its end and each half regrows lost part of the regeneration, to make the adult stem cell division and differentiation, leading to two worms.

[Zachary Williams]

"the real question: why must all cells of multicellular organisms contain the same genome? is it always this way on earth? 'cause i want to know if a multicelular organism can line up with another and exchange genes cell by cell and remain multicellular.

i should look at fungi."

Lichens. Fungus + algae. No idea whether there's evidence of gene exchange, though. I bet someone has looked into this, wonder if I can find some papers...

[Anthony Vecchiarelli]

Some species of planaria are exclusively asexual. At least in a lab setting.
The planarian detaches its tail end and each half regrows the lost parts by regeneration, allowing adult stem cells to divide and differentiate, thus resulting in two worms.

[barry]

the real question: why must all cells of multicellular organisms contain the same genome? is it always this way on earth? 'cause i want to know if a multicelular organism can line up with another and exchange genes cell by cell and remain multicellular.

i should look at fungi.

i suppose bacterial biofilms could be considered an example of this. sort of.

i got to thinking of all this while reading j.t. bonner