Field of Science

Sunday Protist -- Notodendrodes: giant tree forams

Foraminifera are wonderful organisms. For a glimpse of their phylogeny, see this diagram, but keep in mind that the majority of forams are actually allogromiids, forams which build their walls of protein as opposed to scavenged material or depositing mineral substances. From the allogromiids there have been several independent origins of non-proteinaceous forams, many building their tests out of sand grains, remnants of prey or their own waste. Test-building is a complicated and highly regulated process (many forams actually select sand grains with the right properties for building their tests!), a topic I should get around to eventually (not with those dark menacing storm clouds rapidly approaching from the horizon signalling the inevitable Armageddon finals). Thus, I figured that for this superficial protist appreciation post one can't go wrong with Notodendrodes, a genus of forams that look like trees!

Notodendrodes, like their sphaerical relative Rhabdammina, build their tests out of sand grains, especially quartz. Unlike Rhabdammina, they also have extensive "root" and "arborescent" structures sticking out of the sphaerical shell and into the sand and up in the air, respectively.

Notodendrodes antarctikos from the deep sea, arborescent structure. Image from Bowser lab, shamelessly stolen from certain course slides.

One must also note that forams extend far beyond their tests: they are surrounded by a complex network of extruded strands of cytoplasm forming the reticulopodia. These networks can be used to capture prey, absorb nutrients and, in some species, transport algal symbionts far outside the shell to harvest light energy. Notodendrodes lives too deep for housing photosynthetic symbionts; it is said to use its root pseudopodia for absorbing nutrients from the sediment and the arborescent network for sifting through the algal rain falling from the surface (Bowser Lab webpage on Notodendrodes ).

Notodendrodes hyalinosphaira. Scalebars: A,B - 2mm; C - 1cm; D - 5mm (DeLaca et al. 2002 J Foram Res)

These cells are quite sophisticated and should make great companions for cell biology research. The reticulopodia are able to move things along them (seems to be widespread feature among Rhizarians), and before you get the idea that these giant cells are docile and harmless, some forams can prey on small animals like copepods. There are some truly frightening micrographs in OR Anderson's Biology of Foraminifera.

Notodendrodes is apparently uninucleate. Wonder what ploidy levels would be needed to sustain such a monster-sized cell...

Anyway, this post fails to do justice to these organisms, but this week is simply awful for me, so I must leave it at that. My whole life is due this week. Also, I have three weeks left to finish wrapping up my current research project, and I'm having great difficulty focusing on it with all the course-related crap on top of it. Expect negligible blogging efforts in the next few weeks...

By the way, Mystery Micrograph #20 feels neglected. Do you guys need a few more micrographs for help?

Meanwhile, some random foram stuff to look at:

Bowser, S. (1995). Larger agglutinated foraminifera of McMurdo Sound, Antarctica: Are Astrammina rara and Notodendrodes antarctikos allogromiids incognito? Marine Micropaleontology, 26 (1-4), 75-88 DOI: 10.1016/0377-8398(95)00024-0

DeLaca, T. et al. (2002). NOTODENDRODES HYALINOSPHAIRA (SP. NOV.): STRUCTURE AND AUTECOLOGY OF AN ALLOGROMIID-LIKE AGGLUTINATED FORAMINIFER The Journal of Foraminiferal Research, 32 (2), 177-187 DOI: 10.2113/0320177

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