TY - JOUR

T1 - Unique horizontal gaze control in the box jellyfish, Tripedalia cystophora

AU - Wiisbye, Sofus Halkjaer

AU - Garm, Anders

PY - 2023

Y1 - 2023

N2 - All known cubozoans, box jellyfish, have a similar visual system. They possess four sensory structures called rhopalia, which carry-six eyes each. Two of these six eyes are true image-forming camera type eyes in several ways similar to vertebrate eyes. The rhopalia hang by a thin flexible stalk and in the distal end, there is a high -density crystal. In an earlier study of the Caribbean species Tripedalia cystophora, we showed that the crystals act as weights ensuring that the rhopalia are always upright no matter the orientation of the medusa and the vertical part of the visual field of the eyes thus kept relatively constant. Here we have examined the horizontal part of the visual field under different experimental conditions including different visual environments. We find that the horizontal gaze direction is largely controlled by the anatomy of the rhopalium and rhopalial stalk, similar to what has previously been shown for the vertical gaze direction. In a vertically oriented medusa, the rhopalia are kept with a 90 degrees angle between them with the lower lens eyes (LLE) pointing inwards. This 90 degrees shift is kept in horizontally swimming medusa, resulting in the left LLE gazing right, the right gazing left, the bottom gazing orally (backwards compared to swimming direction), and the top LLE gazing aborally (forwards compared to swimming direction). The light environment was manipulated to test if the visual input influences this seemingly strict horizontal gaze direction but even in complete darkness there is tight mechanistic control.

AB - All known cubozoans, box jellyfish, have a similar visual system. They possess four sensory structures called rhopalia, which carry-six eyes each. Two of these six eyes are true image-forming camera type eyes in several ways similar to vertebrate eyes. The rhopalia hang by a thin flexible stalk and in the distal end, there is a high -density crystal. In an earlier study of the Caribbean species Tripedalia cystophora, we showed that the crystals act as weights ensuring that the rhopalia are always upright no matter the orientation of the medusa and the vertical part of the visual field of the eyes thus kept relatively constant. Here we have examined the horizontal part of the visual field under different experimental conditions including different visual environments. We find that the horizontal gaze direction is largely controlled by the anatomy of the rhopalium and rhopalial stalk, similar to what has previously been shown for the vertical gaze direction. In a vertically oriented medusa, the rhopalia are kept with a 90 degrees angle between them with the lower lens eyes (LLE) pointing inwards. This 90 degrees shift is kept in horizontally swimming medusa, resulting in the left LLE gazing right, the right gazing left, the bottom gazing orally (backwards compared to swimming direction), and the top LLE gazing aborally (forwards compared to swimming direction). The light environment was manipulated to test if the visual input influences this seemingly strict horizontal gaze direction but even in complete darkness there is tight mechanistic control.

KW - Cubozoa

KW - Vision

KW - Eyes

KW - Visual field

KW - JELLYFISH TRIPEDALIA-CYSTOPHORA

KW - CENTRAL-NERVOUS-SYSTEM

KW - FINE-STRUCTURE

KW - EYE-MOVEMENTS

KW - VISION

KW - CUBOMEDUSAN

KW - CNIDARIA

KW - STARFISH

KW - OPTICS

KW - OCELLI

U2 - 10.1016/j.visres.2022.108159

DO - 10.1016/j.visres.2022.108159

M3 - Journal article

C2 - 36516604

VL - 203

JO - Vision Research

JF - Vision Research

SN - 0042-6989

M1 - 108159

ER -