Fig. 1

NvLWamide-like::mCherry + longitudinal and tripolar neuronal number positively correlate with length. a NvLWamide-like::mCherry positive animal showing the different neuronal subtypes used in this study. Arrowheads in a identify tentacular neurons. a’ ×10 magnification, showing pharyngeal neurons. a” × 20 magnification and different focal planes, demonstrating the location of neural subtypes present in the body column, within separate tissues. Tripolar neurons, located in the ectoderm, are captured in a superficial focal plane of the animal. Longitudinal neurons, residing in the endoderm, are captured in a deeper focal plane of the animal in the same location. Arrowheads identify neural subtypes labeled within each panel. b Schematic of NvLWamide-like-expressing neural subtypes. c Schematic depicting anatomical structures of an adult Nematostella. d, e There is a strong positive correlation between animal length and the number of longitudinal (r₁₄₄ = 0.854, p < 0.001, n = 146) and tripolar neurons (r₁₄₄ = 0.791; p < 0.001, n = 145). Scale bars = 100 μm