Functionally redundant peg sensilla on the scorpion pecten

Abstract

All scorpions have two mid-ventral organs called pectines. Each pecten has thousands of pore-tipped sensilla sensitive to a variety of volatile organic and water-based stimulants. However, it was previously unknown whether individual sensilla were functionally identical or different. The information enhancement hypothesis predicts that all sensilla have similar chemosensitivities such that each is a unit of a parallel processing system. The information segmentation hypothesis states that sensilla differ in their chemosensitivities, a functional arrangement akin to the glomeruli-specific chemical detection system in the moth or human olfactory sense. In this study, we tested these hypotheses by extracellularly tip-recording sensillar responses to three aqueous tastants: 0.01 M KCl, 0.1 M citric acid, and 40% ethanol by volume. We isolated stimulation to one sensillum at a time and compared the chemoresponses. Sensilla appeared to respond similarly to the same stimulant (i.e., sensillar tip-recordings revealed activity of the same cell types), although sometimes a few sensilla responded with higher spike rates than the others. We conclude that our data primarily support the information enhancement hypothesis but for future tests of sensillar function we suggest a new hybrid model, which proposes that a few specialized sensilla exist among a mostly uniform field of identical sensilla.

High-throughput simulations indicate feasibility of navigation by familiarity with a local sensor such as scorpion pectines

“…Deflection of the peg while 40recording from the base also elicits a phasic mechanoreceptor response [12,25]. Tip 41 recordings from hundreds of P. utahensis pegs with citric acid, ethanol, or KCl added to 42 the electrolyte in the glass electrode show that the pegs respond to all three stimulants 43 in a characteristic yet uniform way [15,26].…”

“…Behavioral [3][4][5], morphological [6][7][8][9][10][11], and physiological [12][13][14][15] evidence indicates that 11 the pectines are organs of taste and touch. However, the full function of these organs 12 remains enigmatic.…”

“…A pecten-like sensor could, for example, be a 40 × 1 grid of sensor pixels that 109 each represents a tooth and corresponds to a 6 × 12 area on the landscape. The choice 110 to model the sensor as a grid corresponds to the grid-like physiology and neurology of 111 the pectines [10,11,15]. 112 We call the grid of sensor pixels resulting from the agent's using its sensor to observe 113 the landscape a "glimpse" consistently with the familiarity literature.…”

“…The grouped nature of the pegs is supported by experimental evidence: It 244 takes approximately eight pegs working in tandem to distinguish between 245 chemicals [15]. While each peg contains a mechanoreceptor [8,9], and the 246 kinetics of the mechanosensory response [12] may yield finer-grained 247 resolution, the textural discrimination power of the pegs has not been tested.…”

Función de los pectenes en detección de presa en hembras del escorpión <em>Centruroides margaritatus </em> (Scorpiones: Buthidae): prueba experimental con grupo control

“…Posteriormente Krapf (1986) evidenció la importancia de los pectenes como estructuras accesorias en la detección y localización de presas muertas y sus secreciones, por incremento en actividad de barrido del sustrato. Por otra parte los estudios sobre funciones de pectenes en su mayoría emplean especies desérticas (Swoveland 1978, Knowlton & Gaffin 2011. Polis & Sissom (1990) señalan que algunas especies muestran adaptaciones ecomorfológicas a diferentes suelos o microhábitats, sin embargo similitudes en apariencia entre escorpiones solapan las diferencias morfológicas.…”