Fig. 4: Feeding behaviour of juvenile and adult C. magus.

The transition to adulthood in C. magus was marked by a shift in prey preference accompanied by morphological and behavioural changes. a Early juveniles were observed to feed exclusively on syllid worms in a “sting-and-stalk” foraging behaviour. Worms were first stabbed by a short unbarbed radular tooth, and the proboscis rapidly withdrawn inside the rostrum, leaving the prey untethered. Venom injection induced hypoactivity in worm prey. The juvenile then stalked its prey before swallowing it whole. b Juvenile radular tooth redrawn from scanning electron microscopy (SEM) (see Supplementary Fig. 2a). This “sting-and-stalk” foraging behaviour was consistent with the juvenile radular tooth lacking apical barbs, blades and serrations. The juvenile radular tooth was short in absolute and relative length and was characterised by a short shaft, a waist and a broad base with a wide opening. c Adult C. magus display the typical “hook-and-line” foraging behaviour, with the fish prey being stung by a hooked radular tooth while potent neurotoxins rapidly induce rigid paralysis. The paralysed fish is then tethered inside the rostrum and swallowed whole. d Adult radular tooth redrawn from SEM (see Supplementary Fig. 4a). Note the presence of the hooked accessory process (ac.pro) at the apex of the tooth that facilitates tethering stung fish. Radular teeth are magnified 25x relative to the size of the animals.