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[APD] RE: Algae Spores

Kyle Williams:
> Plants form spores all the time, its critical to how they
> reproduce sexually.

Pollen should qualify as spores however it needs to merge with an ovum in order to produce a viable embryo. Why be exclusive? We
animals also produce unicellular, gamete, motile zoospores known as spermatozoa! The female ovum is also a unicellular gamete but
not motile.

Spores are not narrowly defined in biology; rather they encompass many organisms. Sexual reproduction always involves the merge of
two distinct cells and a sharing of chromosomal material.

What we think of as spores are really the product of fungi, which release spores in the billions to float in the air. Human spores
almost never float in the air. Like the majority of other spore organisms, they can live only in a specialized environment for a few
days at best.

> Actually you are closer to correct if you
> refer to green algae only and not include the land plants,
> but I'm sure that at least some green algae make spores.

Spirogyra certainly produce spores. The following from my Internet notes (not sure of attribution):

"Sexual- When spirogyra is living in a poor or harsh environment, they reproduce sexually. This is called conjugation. Two filaments
line up next to each other. Next the cells of the spirogyra create tubes called conjugation tubes. The two filaments fuse together
by connecting their conjugation tubes. Only one filament pushes its genetic material through the conjugation tubes. A zygospore
forms in each cell of the filament where the genetic material was pushed to. The zygospores can survive harsh conditions. They can
survive long after the pond has dried up because it is covered with a tough shell. When the living conditions improve, the zygospore
opens and new spirogyra chains grow."

These spores are not motile (swimming) and rely upon chance to move from location to location. Only the zygospores survive
desiccation within the old, parent filaments.

For more on Spirogyra see:


Oedogonium produce motile spores (zoospores). They have small box-like cells called antheridia containing a pair of male gamete
zoospores. These grow endogenously (within the cell). Other filaments produce large round cells called OOGONIA containing a single
female gamete. The male zoospores are chemically attracted to a pore on the side of the oogonia by which they merge to form a
zygote. This zygote can lie dormant for a very long time. When conditions are propitious, the zygote splits to produce four motile
zoospores, each of which is free swimming and can divide asexually to produce a new filament. The base of the filament is a
differentiated cell which anchors the filament.

Introduction to the Chlorophyceae (green freshwater algae)

> Assuming you mean airborne spores you may well be correct
> about the filamentous algae in our tanks, but I'm not a
> phycologist so I won't say much there.

Thomas is the resident phycologist. I don't know the classification or species of the common green thread algae that we see in
aquariums. I hope that somebody will enlighten us!

Q1. Thomas, what species or genera of green filament algae have you identified in aquaria?

Q2. Do you identify the particular species when you find Oedogonium for example?

Q3. Where do you get algae specimens if you are doing an experimental study?

> ...  Seeds are
> spore-like..

Seeds contain a well developed multi-cellular embryo. The cells have already begun to differentiate.

Spores are usually uni-cellular but can be multi-cellular. The term has been in common usage for so long that its not very
discriminatory. I suspect that we could argue that spores are one or more undifferentiated cells which are capable of developing
into complete individuals. Haploid zoospores can't do that on their own; they have to merge with another gamete. Should they be
called spores?

Some seeds can travel short distances on the wind because they develop appendages like wings or fuzz. They are much larger than
single cell spores and so I don't think its right to confuse them. For the purposes of our discussion, I believe we're talking about
microscopic dust that is ubiquitous in the environment and allegedly able to infect our aquariums with all types of dreaded filament
algae. It simply ain't so. :-) OTOH, there ARE plenty of opportunities to spread filament algae from tank to tank with equipment,
nets and so forth.


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