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Several bright red plasmodia of Raspberry Slime Mold
(Tubifera ferruginosa) on a log. Rowan County, NC. |
This spring
was cool and wet, the perfect weather for
slime molds.
These amazing creatures are
not really Fungi as the mold in their name suggests, but are classified with
amoebas.
Slime molds all have an amoeba
stage in their life cycles.
There are several groups of microbes that are called slime molds. The ones we
have seen this spring are all giant amoebas.
These monstrous cells, called plasmodia, and can be several inches
across.
Plasmodia are often brightly
colored and they contain millions of nuclei.
These huge cells crawl across leaf litter or rotting logs and engulf any
microorganism in their path.
Eventually
the plasmodium produces fruiting bodies that release spores.
These reproductive cells float on the breeze
and germinate into new amoebas that then grow into new plasmodia.
Slime molds were the inspiration for the
classic 1950s sci fi movie,
The Blob.
In this film, a giant plasmodium oozes around
a Pennsylvania town consuming the citizenry.
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Close up of Raspberry slime mold showing the red
bumps that resemble a raspberry fruit. Rowan County, NC. |
On a drizzly day in May, we were hiking through the woods in
a local park. As we rounded a curve in
the trail, we saw brilliant red slime molds on the trunk of a downed tree. This was a group plasmodia of the Raspberry
Slime Molds (Tubifera ferruginosa). The
plasmodia had many small red bumps that mimic the compound fruits of
raspberry. The Raspberry Slime Mold was
getting ready to make spores. When we returned two days later, the spore
producing sporangia were mature and had turned dark brown.
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Raspberry Slime Mold with white stalks supporting
the developing sporgangia. Rowan County, NC. |
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Raspberry Slime mold as the sporangia develop.
Rowan County, NC. |
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Raspberry Slime Mold with mature, brown sporangia.
These structures were releasing spores. Rowan County, NC. |
Another slime mold we found this spring was a bright white
one, Ceratiomyxa fruticulosa, the
Coral Slime Mold. This slime mold was
also growing on a log and the delicate, branched white fruiting bodies stood
out against the black of the log.
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White plasmodia of Coral Slime Mold (Ceratiomyxa fruticulosa)
on a decaying log. Rowan County, NC. |
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Closeup of of Coral Slime Mold plasmodia.
Rowan County, NC. |
Near the
Coral Slime Mold, we found another interesting one,
Arcyria cinerea.
This slime
mold is one of the most common on rotting logs but does not have a common name.
Arcyria cinerea makes delicate,
cylindrical, gray sporangia.
|
Sporangia of Arcyria cinerea. Rowan County. NC. |
Physarum
polycephalum lives in leaf litter or on rotten logs. This common slime mold is bright yellow and
the plasmodium can be a foot across. Physarum polycephalum is the lab rat of
slime molds because its large cell size makes it important in the study cell movement.
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Giant plasmodium of Physarum polycephalum. Rowan County, NC. |
This spring we also saw a beautiful yellow slime mold with an
unappealing name, Dog Vomit Slime Mold (
Fuligo
septica).
The large, bright yellow
plasmodium gives this organism another common name, Scrambled Egg Slime.
Dog
Vomit Slime Mold often appears on wood chip mulch but may also show up on dead
wood of many types.
Dog Vomit Slime Mold
has the curious ability to concentrate the metal zinc in its plasmodium.
Russian researchers found
Fuligo septica plasmodia contain more than
20 times the environmental concentration of zinc.
The reason for this hyper-accumulation of a
toxic metal is unknown, but the yellow pigment of the slime mold helps
sequester the zinc and make it less toxic. After crawling around consuming
other microbes, the bright yellow plasmodium turns brown and produces spores.
This spore generating stage really does look
like dog vomit.
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A migrating plasmodium of Dog Vomit Slime Mold (Fuligo septica).
Rowan County, NC. |
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Dog Vomit Slime Mold releasing spores.
Rowan County, NC. |
Leaf
litter, soil and rotting logs are the natural habitat of countless protozoa, bacteria,
fungi and algae.
This biodiversity is
mostly invisible to us, but in the case of slime molds their giant cells let us
get a glimpse of this world.