Animálculos que ruedan / Wheeled animalcules

Los rotíferos fueron observados,descritos y dibujados por el grandísimo microscopista holandés Leeuwenhoek, hace ya más de tres siglos. Los llamó animálculos que ruedan. Estas ilustraciones son un pequeño homenaje a él pues tener la fortuna de poder usar un foldscope puede hacernos revivir lo que debió sentir aquel pañero en una Europa que desconocía el mundo de los microorganismos y que, sin estudios superiores y con un ingenio superlativo, retó a los científicos de la Real Sociedad de Londres.

Rotifera were observed, described and drawn by the greatest dutch microscopist Leeuwenhoek, about three centuries ago. He named them wheeled animalcules. These videos are a tribute to him due to the incredible experience that the use of foldscope has meant to me: the wonder of discovering the tiniest, just as this textile merchant must have felt in an European continent unaware of the microcosmos. He himself, with no University attendance and an awesome ingeniosity, challenged the scientific members at the London Royal Society.

En este vídeo se puede observar cómo son capaces de crear torbellinos de agua gracias a la corona de cilios. Asimismo, se percibe el movimiento del mástax, órgano faríngeo para la digestión mecánica.

In this video, water whirls created by their crowns of cilia can be observed. The movement of the jaws located in the pharynx are visible too.

La lucha constante por atraer pequeños microorganismos actuando como verdaderas aspiradoras acuáticas.

The continuous struggle to attract smaller microorganisms acting as aquatic “vacuum-cleaners”.


No siempre viven fijos a un sustrato, sino que pueden desplazarse nadando mediante el movimiento de sus cilios.

They do not always live attatched to soil or debris, and can swim around by moving their cilia.



4 Comments Add yours

  1. laksiyer says:

    These are just stupendous videos. What always impresses me about the Bdelloid rotifers is there ability to just be parthenogenetic and avoid Muller’s Ratchet, perhaps by horizontal gene transfer. Some calculate its been 40 million years of asexuality!!

  2. Manu Prakash says:

    The flow fields that they can generate are quiet strong actually.

    @Laks: for the genetically challenged (I mean challenged in genetics theory) amongst us – can you explain Mullers ratchet and the crucial aspects of 40 million years of asexuality. Do we know for sure that they are asexual?


  3. laksiyer says:

    Hi @Manu.
    Muller’s ratchet is the accumulation of deleterious mutations in an irreversible way. When you have a species without recombination (sexual, lateral transfer etc), then the species will accumulate deleterious mutations in the population. After a few generations, depending on genome size, the deleterious mutations will exist in every individual leading the species to be extinct. This was first proposed by the geneticist Muller and later this was called the Ratchet (a devise which you well know about that only leads to motion in one direction). This led to the postulate that most eukaryotes have sexual reproduction to overcome the ratcheting effect of asexuaity, because during meiosis there is recombination by which there is a chance that deleterious regions will be excluded in the descendants.

  4. laksiyer says:

    Now with respect to the Rotifers, the Bdelloid rotifers have been studied for sometime and there has been no evidence of sexual reproduction in this species. Usually, the absence of sexual reproduction means that we havent looked hard enough, but this far no one has observed sexual reproduction in the Bdelloids even after many generations of culturing. The renowed Matthew Meselson, whose experiments provided proof for semi conservative DNA replication, studied this problem and found out that allelic genes, i.e. genes present on the same chromosome in the diploid animal are very different from each other in the Bdelloid rotifers as compared to the non-Bdelloids. further supporting the lack of a sex-based resolution. However, there might be cryptic sex, or hermaphroditism that hasnt been seen. There is a very good paper on this.
    40 million years value comes from the oldest amber with a Bdelloid rotifer fossil.

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