Neuroecology beyond the brain: learning in Echinodermata

Area of Science:

• Neuroecology
• Evolutionary Biology
• Comparative Cognition

Background:

• Echinoderms (starfish, sea urchins, etc.) lack centralized brains, possessing only nerve nets.
• They are evolutionarily close to chordates, which exhibit complex learning and brains.
• Understanding echinoderm learning can illuminate nervous system evolution in Bilateria.

Purpose of the Study:

• To systematically search for and synthesize evidence of learning in echinoderms.
• To explore the evolutionary significance of learning in brainless organisms.
• To compare echinoderm learning with that of vertebrates like fish.

Main Methods:

• Systematic literature search for studies on learning in Echinodermata.
• Analysis of evidence for non-associative and associative learning.
• Comparative analysis with learning in other animal groups, including vertebrates.

Main Results:

• Evidence of non-associative learning found in echinoderms.
• Evidence of associative learning (classical conditioning) documented in starfish, brittle stars, sea urchins, and sand dollars.
• Learning capabilities exist in organisms without centralized brains.

Conclusions:

• Echinoderms exhibit learning, challenging the necessity of a centralized brain for cognitive processes.
• Embodied cognition is present in diverse groups, including brainless invertebrates.
• The study expands neuroecological comparisons to include non-neural and brainless organisms, informing the evolution of learning and nervous systems.