An electrophysiological investigation of power-amplification in the ballistic mantis shrimp punch

Author Posting. © Faculty for Undergraduate Neuroscience, 2019. This article is posted here by permission of Faculty for Undergraduate Neuroscience for personal use, not for redistribution. The definitive version was published in Journal of Undergraduate Neuroscience Education 17(1), (2019): T12-T19.Mantis shrimp are aggressive, burrowing crustaceans that hunt using one the fastest movements in the natural world. These stomatopods can crack the calcified shells of prey or spear down unsuspecting fish with lighting speed. Their strike makes use of power-amplification mechanisms to move their limbs much faster than is possible by muscles alone. Other arthropods such as crickets and grasshoppers also use power-amplified kicks that allow these animals to rapidly jump away from predator threats. Here we present a template laboratory exercise for studying the electrophysiology of power-amplified limb movement in arthropods, with a specific focus on mantis shrimp strikes. The exercise is designed in such a way that it can be applied to other species that perform power-amplified limb movements (e.g., house crickets, Acheta domesticus) and species that do not (e.g., cockroaches, Blaberus discoidalis). Students learn to handle the animals, make and implant electromyogram (EMG) probes, and finally perform experiments. This integrative approach introduces the concept of power-amplified neuromuscular control; allows students to develop scientific methods, and conveys high-level insights into behavior, and convergent evolution, the process by which different species evolve similar traits.Author GJG declares a commercial interest in the SpikerBox used here as a co-owner in Backyard Brains. Authors ES and SM are employed by Backyard Brains. DJP and GJG were supported by a National Institute of Mental Health (NIMH) Small Business Innovative Research (SBIR) award #R44MH093334. Author KDF is funded by European Commission Marie Sklodowska-Curie Independent Postdoctoral Research Fellowship and the Grass Foundation

Long-Wavelength Reflecting Filters Found in the Larval Retinas of One Mantis Shrimp Family (Nannosquillidae).

Both vertebrates and invertebrates commonly exploit photonic structures adjacent to their photoreceptors for visual benefits. For example, use of a reflecting structure (tapetum) behind the retina increases photon capture, enhancing vision in dim light [1-5]. Colored filters positioned lateral or distal to a photoreceptive unit may also be used to tune spectral sensitivity by selective transmission of wavelengths not absorbed or scattered by the filters [6-8]. Here we describe a new category of biological optical filter that acts simultaneously as both a transmissive spectral filter and narrowband reflector. Discovered in the larval eyes of only one family of mantis shrimp (stomatopod) crustaceans (Nannosquillidae), each crystalline structure bisects the photoreceptive rhabdom into two tiers and contains an ordered array of membrane-bound vesicles with sub-wavelength diameters of 153 ± 5 nm. Axial illumination of the intrarhabdomal structural reflector (ISR) in vivo produces a narrow band of yellow reflectance (mean peak reflectivity, 572 ± 18 nm). The ISR is similar to several synthetic devices, such as bandgap filters, laser mirrors, and (in particular) fiber Bragg gratings used in optical sensors for a wide range of industries. To our knowledge, the stomatopod larval ISR is the first example of a naturally occurring analog to these human-made devices. Considering what is known about these animals' visual ecology, we propose that these reflecting filters may help improve the detection of pelagic bioluminescence in shallow water at night. VIDEO ABSTRACT

Additions to Philippine Slender Skinks of the <i>Brachymeles bonitae </i>Complex (Reptilia: Squamata: Scincidae) III:a new species from Tablas Island

Davis, Drew R., Geheber, Aaron D., Watters, Jessa L., Penrod, Michelle L., Feller, Kathryn D., Ashford, Alissa, Kouri, Josh, Nguyen, Daniel, Shauberger, Kathryn, Sheatsley, Kyra, Winfrey, Claire, Wong, Rachel, Sanguila, Marites B., Brown, Rafe M., Siler, Cameron D. (2016): Additions to Philippine Slender Skinks of the Brachymeles bonitae Complex (Reptilia: Squamata: Scincidae) III: a new species from Tablas Island. Zootaxa 4132 (1), DOI: http://doi.org/10.11646/zootaxa.4132.1.

Morphological and molecular description of the late-stage larvae of Alima Leach, 1817 (Crustacea: Stomatopoda) from Lizard Island, Australia

Feller, Kathryn D., Cronin, Thomas W., Ahyong, Shane T., Porter, Megan L. (2013): Morphological and molecular description of the late-stage larvae of Alima Leach, 1817 (Crustacea: Stomatopoda) from Lizard Island, Australia. Zootaxa 3722 (1), DOI: http://dx.doi.org/10.11646/zootaxa.3722.1.

Surf and turf vision: Patterns and predictors of visual acuity in compound eye evolution

Eyes have the flexibility to evolve to meet the ecological demands of their users. Relative to camera-type eyes, the fundamental limits of optical diffraction in arthropod compound eyes restrict the ability to resolve fine detail (visual acuity) to much lower degrees. We tested the capacity of several ecological factors to predict arthropod visual acuity, while simultaneously controlling for shared phylogenetic history. In this study, we have generated the most comprehensive review of compound eye visual acuity measurements to date, containing 385 species that span six of the major arthropod classes. An arthropod phylogeny, made custom to this database, was used to develop a phylogenetically-corrected generalized least squares (PGLS) linear model to evaluate four ecological factors predicted to underlie compound eye visual acuity: environmental light intensity, foraging strategy (predator vs. non-predator), horizontal structure of the visual scene, and environmental medium (air vs. water). To account for optical constraints on acuity related to animal size, body length was also included, but this did not show a significant effect in any of our models. Rather, the PGLS analysis revealed that the strongest predictors of compound eye acuity are described by a combination of environmental medium, foraging strategy, and environmental light intensity

A shape-anisotropic reflective polarizer in a stomatopod crustacean.

Many biophotonic structures have their spectral properties of reflection 'tuned' using the (zeroth-order) Bragg criteria for phase constructive interference. This is associated with a periodicity, or distribution of periodicities, parallel to the direction of illumination. The polarization properties of these reflections are, however, typically constrained by the dimensional symmetry and intrinsic dielectric properties of the biological materials. Here we report a linearly polarizing reflector in a stomatopod crustacean that consists of 6-8 layers of hollow, ovoid vesicles with principal axes of ~550 nm, ~250 nm and ~150 nm. The reflection of unpolarized normally incident light is blue/green in colour with maximum reflectance wavelength of 520 nm and a degree of polarization greater than 0.6 over most of the visible spectrum. We demonstrate that the polarizing reflection can be explained by a resonant coupling with the first-order, in-plane, Bragg harmonics. These harmonics are associated with a distribution of periodicities perpendicular to the direction of illumination, and, due to the shape-anisotropy of the vesicles, are different for each linear polarization mode. This control and tuning of the polarization of the reflection using shape-anisotropic hollow scatterers is unlike any optical structure previously described and could provide a new design pathway for polarization-tunability in man-made photonic devices