Monterey Bay Aquarium Research Institute
Marine Botany

Mazzaella flaccida (was Iridaea) Life History Scrapbook


Gametophyte

Three Beautiful Gametophytes

  • Beautiful, iridescent
  • Slippery
  • Haploid generation, sexes separate, bears gametes.
  • Female gametophyte becomes carposporophyte when fertilized by male's spermatia.

Carposporophyte

worn out carposporophytes

Notice how the carposporophyte on the left has tattered. The trouser tear test revealed that the carposporophyte is weakest towards its stipe. The carposporophyte on the left, like many I observed on the Monterey coast, experienced tattering on the lower part of its blade first. The carposporophyte on the right has almost completely tattered, but you can still see that the middle of the blade rather than the tip seems to have disintegrated most quickly.

  • Used to be female gametophyte
  • Haploid blade bears diploid carpospores in sori, called carposporangia

Carposporangia

section of carposporophyte

Click on the picture of this carposporophyte to view it larger. See what happens when the sorus is sectioned more thinly and its carpospores explode from their tight packing.

carpospores

Each of the round bodies is a carpospore; the group of them composes the carposporangium. The upper right corner of the photo shows Iridaea's fillamentous medulla while the cortex, or surface cells, are just visible in the lower left corner.


Tetrasporophyte

tetrasporophyte blade

Notice the smooth margins or the tetrasporophyte which lack tetrasporangia, the dark dots.

  • Diploid blade sprouted from diploid carpospores
  • Site of meiosis during formation of haploid tetraspores
  • Cruciate tetraspores in sori, called tetrasporangia

Tetrasporangia

tetraspores                    tetrasporoangia

These prize pictures show the last stage of Iridaea's life history. The first depicts a tetrasporanial sorus, or tetrasporangium, located on the blade of the tetrasporophyte. Just visible are round lumps, tetraspores, which have four 1n spores. The last photo, captured from videotape, provides a closeup view of one of these cruciate tetraspores.


A Family Photo

three life history stages

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