The Proboscis of Predatory Conus: Sensory Structures and Tissue Regeneration

Abstract

Within the last 50 million years members of the Family Conidae have evolved into over 500 highly specialized and venomous species of predatory marine snails. There has been relatively little work done on gross morphology and comparative biology of these snails. Recent work has shown a novel mechanism in their proboscis that uses a harpoon to inject toxin into a prey item. Their rapid evolution and specialization has produced three basic groups of cone snails; vermivores, piscivores and molluscivores. The three basic groups of cone snail all show a remarkable ability to locate and dispatch prey. With a nocturnal lifestyle, limited eyesight and speed, it was still unknown how these identify and locate their prey. Through an integrated approach we have discovered ciliated sensory organs (?sensory papillae?) near the distal tip of this proboscis. Scanning electron microscopy has shown these structures to be similar within species of at least two of the three groups. Confocal and fluorescent microscopy was used to see extensive innervation within the proboscis leading up to the sensory papillae. Additional studies using fluorescent microscopy, light microscopy and transmission electron microscopy revealed that these complex sensory structures can regenerate after the tip of the proboscis has been ablated, which happens in the wild as well as in lab settings. My goal is to identify the nervous innervation of these sensory structures and to compare the morphology of the sensory papillae in members of all three groups of cone snails.