Menu

Close

The physiological adaptation for the “fore-mid” four-legged walking behavior of the pygmy mole cricket Xya sichuanensis

Yi Zhang, Shuying Wang, Zhu-Jun Feng, Tong-Xian Liu, Chengquan Cao

Preprint posted on April 02, 2020 https://www.biorxiv.org/content/10.1101/2020.03.22.002675v2

The floor is lava for pygmy mole cricket hind legs: X. sichuanensis walks and runs only on its fore and mid legs, while conserving hind legs for jumping. These are flexed + held in grooves along the abdomen forming a specialized structure

Selected by Matt Muzzatti

Background

Pygmy mole crickets (Orthoptera: Tridactylidae) are an incredible product of natural selection; they have unique mole-like forelegs used for building burrows, and like many other Orthoptera species have well-developed hind legs used for jumping. Some Tridactylidae can even launch themselves off the surface of water using highly specialized hind legs (Burrows and Picker 2010; Burrows and Sutton 2012). But this specialization is not without a trade-off, as Xya sichuanensis, a pygmy mole cricket native to Leshan, China, has been observed walking only on its fore and mid legs. Quadrupedalism (four-legged walking) has been recorded in other insects such as mantids, water striders, and brush-footed butterflies, but these insects have modified forelegs used for seizing prey and walk on their mid and hind legs. Although most Orthoptera have specialized hopping hind legs, they use a tripedal strut using all six legs. In this preprint, Zhang et al. used scanning electron microscopy, histological staining, and walking pattern analysis to analyze the “fore-mid leg” walking motion of X. sichuanensis and its associated morphological adaptations.

Figure 1. Dorsal (A) and transverse (B) views of Xya sichuanensis. From Zhang et al. 2020 under a CC-BY-NC-ND 4.0 International license.

Key findings

It was confirmed that the hind legs do not contact the ground when stationary, walking, or running, which is accomplished by ‘flexing’ the hind legs (tibia is resting on top of the femur, Fig. 2C). This walking style is assisted by a comparatively wider supporting area for four legs, relative to other insects. The flexed hind legs fit into grooves along the dorsal surface of the abdomen, and combined with short wings, fit together to form an integrated structure (Fig. 2E). The ventral abdominal cuticle remains in contact with the ground acting as a fulcrum point and is significantly thicker than other abdominal cuticles. This thickened abdomen is hypothesized to protect the cricket from friction while walking or running.

Two different movement patterns were discovered, one for walking and another for running, which allow for the specialized four-legged movement in X. sichuanensis.

Zhang et al. argue that the highly specialized hind legs of X. sichuanensis indicate that natural selection favoured improved jumping over six-legged walking, and thus during its evolutionary pathway, jumping was more important for its survival. This in turn drove the other four legs and the abdomen to evolve in support of walking.

Figure 2. A sketch of Xya sichuanensis hing leg (C) and the hind leg-wing-abdomen process (E). From Zhang et al. 2020 under a CC-BY-NC-ND 4.0 International license.

What I like about this preprint

I focused on the incredible morphology displayed in these crickets – the hing leg-wing-abdomen process is a beautiful product of evolution, and is eloquently illustrated by the authors. It reminds me of a transformer toy from childhood, where many different pieces fit together perfectly in a picturesque model of design and engineering. This preprint includes some fantastic in-depth diagrams of the slow-walking and running patterns exhibited by X. sichuanensis, so if behaviour is your thing, I highly suggest reading this paper.

The figures and diagrams in this manuscript are gorgeous. I only included a few figures from the manuscript, but the scanning electron micrographs and histological abdomen cross section figures are worth checking out.

Finally, this is a wonderful depiction of a highly specialized morphological adaptation resulting in a unique insect behaviour. This study contributes to the already weird and wonderful world of insects and provides valuable insight into movement behaviour among insects.

Future directions

Some open questions Zhang et al. propose include:

  • How does the jumping behaviour of X. sichuanensis drive organ specialization?
  • How does X. sichuanensis adapt to complex walking conditions?

Question for the authors

If adult crickets were used in this experiment, could the thickened cuticle on the abdomen just be a result of a lifetime of friction, sort of how callouses develop on human skin? Or are X. sichuanensis born with thickened cuticles and maintain that feature through its nymphal stages?

References

Burrows, M. and Picker, M.D. 2010. Jumping mechanisms and performance of pygmy mole crickets (Orthoptera, Tridactylidae). Journal of Experimental Biology 213, 2386-2398.

Burrows, M. and Sutton, G.P. 2012. Pygmy mole crickets jump from water. Current Biology 22, R990-R991.

Zhang, Y., Wang, S., Feng, Z.J., Lie, T.X., and Cao, C. 2020. The physiological adaptation for the “fore-mid” four-legged walking behavior of the pygmy mole cricket Xya sichuanensis. Preprint posted April 2, 2020. https://doi.org/10.1101/2020.03.22.002675

 

Posted on: 25th April 2020 , updated on: 11th May 2020

doi: https://doi.org/10.1242/prelights.19335

Read preprint (No Ratings Yet)




  • Have your say

    Your email address will not be published. Required fields are marked *

    This site uses Akismet to reduce spam. Learn how your comment data is processed.

    Sign up to customise the site to your preferences and to receive alerts

    Register here

    preLists in the developmental biology category:

    Planar Cell Polarity – PCP

    This preList contains preprints about the latest findings on Planar Cell Polarity (PCP) in various model organisms at the molecular, cellular and tissue levels.

     



    List by Ana Dorrego-Rivas

    Cell Polarity

    Recent research from the field of cell polarity is summarized in this list of preprints. It comprises of studies focusing on various forms of cell polarity ranging from epithelial polarity, planar cell polarity to front-to-rear polarity.

     



    List by Yamini Ravichandran

    TAGC 2020

    Preprints recently presented at the virtual Allied Genetics Conference, April 22-26, 2020. #TAGC20

     



    List by Maiko Kitaoka, Madhuja Samaddar, Miguel V. Almeida, Sejal Davla, Jennifer Ann Black, Gautam Dey

    3D Gastruloids

    A curated list of preprints related to Gastruloids (in vitro models of early development obtained by 3D aggregation of embryonic cells)

     



    List by Paul Gerald L. Sanchez and Stefano Vianello

    ASCB EMBO Annual Meeting 2019

    A collection of preprints presented at the 2019 ASCB EMBO Meeting in Washington, DC (December 7-11)

     



    List by Madhuja Samaddar, Ramona Jühlen, Amanda Haage, Laura McCormick, Maiko Kitaoka

    EDBC Alicante 2019

    Preprints presented at the European Developmental Biology Congress (EDBC) in Alicante, October 23-26 2019.

     



    List by Sergio Menchero, Jesus Victorino, Teresa Rayon, Irepan Salvador-Martinez

    EMBL Seeing is Believing – Imaging the Molecular Processes of Life

    Preprints discussed at the 2019 edition of Seeing is Believing, at EMBL Heidelberg from the 9th-12th October 2019

     



    List by Gautam Dey

    SDB 78th Annual Meeting 2019

    A curation of the preprints presented at the SDB meeting in Boston, July 26-30 2019. The preList will be updated throughout the duration of the meeting.

     



    List by Alex Eve

    Lung Disease and Regeneration

    This preprint list compiles highlights from the field of lung biology.

     



    List by Rob Hynds

    Young Embryologist Network Conference 2019

    Preprints presented at the Young Embryologist Network 2019 conference, 13 May, The Francis Crick Institute, London

     



    List by Alex Eve

    Pattern formation during development

    The aim of this preList is to integrate results about the mechanisms that govern patterning during development, from genes implicated in the processes to theoritical models of pattern formation in nature.

     



    List by Alexa Sadier

    BSCB/BSDB Annual Meeting 2019

    Preprints presented at the BSCB/BSDB Annual Meeting 2019

     



    List by Gautam Dey

    Zebrafish immunology

    A compilation of cutting-edge research that uses the zebrafish as a model system to elucidate novel immunological mechanisms in health and disease.

     



    List by Shikha Nayar
    Close