TY - JOUR

T1 - Associative learning in the box jellyfish Tripedalia cystophora

AU - Bielecki, Jan

AU - Dam Nielsen, Sofie Katrine

AU - Nachman, Gösta

AU - Garm, Anders

N1 - Publisher Copyright: © 2023 Elsevier Inc.

PY - 2023

Y1 - 2023

N2 - Associative learning, such as classical or operant conditioning, has never been unequivocally associated with animals outside bilatarians, e.g., vertebrates, arthropods, or mollusks. Learning modulates behavior and is imperative for survival in the vast majority of animals. Obstacle avoidance is one of several visually guided behaviors in the box jellyfish, Tripedalia cystophora Conant, 1897 (Cnidaria: Cubozoa), and it is intimately associated with foraging between prop roots in their mangrove habitat. The obstacle avoidance behavior (OAB) is a species-specific defense reaction (SSDR) for T. cystophora, so identifying such SSDR is essential for testing the learning capacity of a given animal. Using the OAB, we show that box jellyfish performed associative learning (operant conditioning). We found that the rhopalial nervous system is the learning center and that T. cystophora combines visual and mechanical stimuli during operant conditioning. Since T. cystophora has a dispersed central nervous system lacking a conventional centralized brain, our work challenges the notion that associative learning requires complex neuronal circuitry. Moreover, since Cnidaria is the sister group to Bilateria, it suggests the intriguing possibility that advanced neuronal processes, like operant conditioning, are a fundamental property of all nervous systems.

AB - Associative learning, such as classical or operant conditioning, has never been unequivocally associated with animals outside bilatarians, e.g., vertebrates, arthropods, or mollusks. Learning modulates behavior and is imperative for survival in the vast majority of animals. Obstacle avoidance is one of several visually guided behaviors in the box jellyfish, Tripedalia cystophora Conant, 1897 (Cnidaria: Cubozoa), and it is intimately associated with foraging between prop roots in their mangrove habitat. The obstacle avoidance behavior (OAB) is a species-specific defense reaction (SSDR) for T. cystophora, so identifying such SSDR is essential for testing the learning capacity of a given animal. Using the OAB, we show that box jellyfish performed associative learning (operant conditioning). We found that the rhopalial nervous system is the learning center and that T. cystophora combines visual and mechanical stimuli during operant conditioning. Since T. cystophora has a dispersed central nervous system lacking a conventional centralized brain, our work challenges the notion that associative learning requires complex neuronal circuitry. Moreover, since Cnidaria is the sister group to Bilateria, it suggests the intriguing possibility that advanced neuronal processes, like operant conditioning, are a fundamental property of all nervous systems.

KW - cnidaria

KW - cubomedusa

KW - electrophysiology

KW - obstacle avoidance behavior

KW - operant conditioning

KW - rhopalial nervous system

U2 - 10.1016/j.cub.2023.08.056

DO - 10.1016/j.cub.2023.08.056

M3 - Journal article

C2 - 37741280

AN - SCOPUS:85172871300

VL - 33

SP - 4150-4159.e5

JO - Current Biology

JF - Current Biology

SN - 0960-9822

IS - 19

ER -