Neptune Aquatics

Largest Single Celled Organism in the World

I was looking at my tank a few nights ago, and I noticed a small green mushroom-like thing growing on the back of one of my snails.
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I realized it was an Acetabularia! Acetabularia is a genus of single-celled, eukaryotic, green algae. This means that although they are unicellular, they are more closely related to plants and even humans than they are to bacteria. What's really unique about them is their size. Most single celled organisms are smaller than the head of a pin (most are MUCH smaller...), but some species of Acetabularia can grow up to 7 cm tall! This specimen is about 1 cm tall, but that is still enormous for a unicellular organism! In order to maintain such a large cell with only one nucleus, these algae have developed special mechanisms to ship metabolic products, RNA, and proteins back and forth between their nucleus in the base of the stalk and the cap where most of their photosynthesis and reproduction happens.

If you don't want a science history lesson, you can stop reading here :p

Early cellular biologists took advantage of this special shipping process and the large size of Acetabularia to demonstrate for the first time that genetic information is kept in the nucleus of eukaryotic organisms. Biologists took two species of Acetabularia with very different looking caps. They cut off the caps and stuck them back on the stalk of the other species (they swapped the caps of the two species). Over time, the caps would change shape and structure until they looked like caps typical of the species to which the stalk belonged. Biologists also used needles to swap the nuclei between two individuals of different Acetabularia species. Again, the cells would slowly change shape and structure until they looked like the species to which the nucleus belonged. This was the first evidence that the nucleus of eukaryotic organisms contains the genetic information.

I thought this was really cool and wanted to share :cool:
 
I just read this now - very interesting. What a cool hobby that things like that just seem to pop up! Will share with biology teachers at my school. Have you found any more of those in your tank during the past month?
 
Not yet. They reproduce via spores that are released from around the periphery of the cap. I bet I'll find more eventually, but they have a reputation of appearing, dissappearing, and reappearing later.

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