Trichoplax adhaerens (Tp) is the only living species in the phylum
Placozoa. Individuals are about 1 mm wide and only 27 μm high, are
irregularly shaped, and consist of a total of about 2,000 cells, which
are diploid (2n = 12). There are four types of cells, none of which are
nerve or muscle cells, and none of which have cell walls. They move
using cilia, and any "edge" can lead. Tp feeds on marine microbes,
mostly unicellular green algae, by crawling atop the algae and trapping
it between its ventral surface and the substrate. Enzymes are then
secreted onto the algae, and the resulting nutrients are absorbed. Tp
sperm cells have never been observed, nor have embryos past the 64-cell
56) In an experiment, several Tp individuals were stained
different colors. The stained individuals were then passed through a
strainer, disaggregated to the level of single cells, and collected into
a common container of seawater. Which subsequent finding would be most
surprising if the Tp individuals used in this experiment had been
produced by sexual, rather than asexual, means?
A) If all of the cells from a given individual reaggregated to form
the same individual, and if each cell had retained its original
identity, as far as cell type goes.
B) If all of the cells from a given individual reaggregated to form
the same individual, but if each cell had a different identity than it
had before disaggregation.
C) If cells from different original individuals reaggregated together to form new individual organisms.
D) If cells from different original individuals reaggregated together to form new species.