Macrobiotus Hufelandi

Macrobiotus Hufelandi is a species of “water bears” in the Macrobiotindae family. This organism can be found all over Eastern continents ranging from Europe down to Africa and even to the Americas. They have many different sub-species and are actively studied due to the high frequency found with estimates between 100-200. They were originally discovered (or classified) in 1834(Bertolani and Rebecchi 1993).

Morphology: This tardigrade is generally anywhere between one to six hundred micrometers in length and their width is unknown due to the nature of how the feed and what environment thy are in. They can come in a variety of different colors a few being yellow, grey or light brown. On the outside of their oral cavity, they have several peribuccal lamellae which create a cheek structure. Inside the oral cavity it consists of 1-3 rows of teeth. Their legs have long double claws for gripping as well as locomotion. The hind claws are generally larger than those towards the front. The cuticle is generally smooth with 1 micrometer diameter pores which occur sporadically over their body. The anus or anterior end consists of an opening with a few claws(Guidetti et al. 2013).

(The photo. above gives an idea of what the first drawing of the entire body of a tardigrade looked like.)

Taxonomy: For a fossil or organism to be put in with this species there are certain morphological features. In a broad sense, the M. hufelandi needs a porous cuticle, up to three bands of teeth in their oral cavity, 2 macroplacoids and 1 microplacoid within the muscles of the pharynx. As studies have gone on, a few other criteria have been deliberated on and uniquely special to the M. hufelandi. The criteria are Y-shaped claws with lunules (crescent shape/marking) on their legs and importantly some egg morphological differences that truly set this species apart from others. Their have to single-walled mushroom-shaped eggs with a smooth chorion (outer membrane) and tubercles on the outside of that. Although these features may seem a bit ambiguous to look at when thinking about how an organism, let alone a small species of Tardigrada, should be classed but interestingly enough, they are important. Although anatomical features are often easier to study in either living organisms or their fossil, when there are over one hundred different sub-species of M. hunfelandi, scientists must do what they may to increase the specificity of such a broad group and make sure the classification is viable (Stec et al. 2021).

(The photo above dipicts one of the first ever Macrobiotus HufeLandi eggs from the orginal discovery in 1834.)

Methods: The creatures are often studied by collecting moss or lichen samples in different areas of the world. Once collected they are subject to a Hoyer’s medium for a quick and fast analysis under a phase contrast microscope. The medium is the most important part of the research plan because it offers the ability to scientists to quickly placed subject matter on the slide and put under a microscope for quick analysis as well as a future storage. Electron scanning microscopes are also used for properly prepared specimens (Kaczmarek et al. 2017).

Further studies: Although tardigrades are almost never talked about in most classes or articles, they are important for the environment, nonetheless. They are known as “Nature’s Pioneers” in that they can adapt to a variety of conditions whether it is air vs. water or cold vs. warm, they can relatively do it all. They collectively absorb almost anything being that they live in a lot of places that you may not think of. An interesting feat that this group of organisms has been able to pull off is surviving in outer space (kind of). A journal article in 2017, Tardigrades in Space Research – Past and Future, gives insight to some tardigrades have the ability to adapt to the high radiation and freezing cold temperatures of outer space. This would be a big step forward in science if these creatures are able to be studied long enough for something to come of it(Weronika et al. 2017) .

Sources:

Weronika E, Łukasz K. Tardigrades in Space Research - Past and Future. Orig Life Evol Biosph. 2017 Dec;47(4):545-553. doi: 10.1007/s11084-016-9522-1. Epub 2016 Oct 20. PMID: 27766455; PMCID: PMC5705745.

Stec, Daniel et al. “New Multilocus Phylogeny Reorganises the Family Macrobiotidae (Eutardigrada) and Unveils Complex Morphological Evolution of the Macrobiotus Hufelandi Group.” Molecular phylogenetics and evolution 160 (2021): 106987–106987. Web.

Kaczmarek, Łukasz, and Łukasz Michalczyk. “The Macrobiotus Hufelandi Group (Tardigrada) Revisited.” (2017): n. pag. Web.

Guidetti, Roberto et al. “The Morphological and Molecular Analyses of a New South American Urban Tardigrade Offer New Insights on the Biological Meaning of the Macrobiotus Hufelandi Group of Species (Tardigrada: Macrobiotidae).” Journal of natural history 47.37-38 (2013): 2409–2426. Web.

BERTOLANI, & REBECCHI, L. (1993). A revision of the Macrobiotus hufelandi group (Tardigrada, Macrobiotidae), with some observations on the taxonomic characters of eutardigrades. Zoologica Scripta, 22(2), 127–152. https://doi.org/10.1111/j.1463-6409.1993.tb00347.x