Description

SINGLE PAPER

Volume 25, Issue 4 – 15 October 2019


Ivan Sazima: Eating out: the Australian pufferfish Tetractenos hamiltoni lunges or blows water at prey situated above water level, pp. 125-132

Abstract
Among the about 30,000 recognized fish species, a handful of them lunges/jumps or spits water at terrestrial prey. The Common Toadfish Tetractenos hamiltoni is a frequent pufferfish in Australian estuaries and mangroves, and feeds opportunistically on anything assessed as edible. I report on two noteworthy foraging behaviours of this pufferfish at a rocky embankment in an estuarine habitat in urban Sydney, south-eastern Australia. Pufferfish usually foraged over the submerged rocks catching crabs and snails, and at water surface they visually examined and/or mouthed and ate floating objects such as insects alive or dead and berries. Some individuals employed a particular foraging mode: they swam very close to rocks that were partly above water level, and inspected every object that resembled a potential prey. The intertidal isopod Ligia australiensis was the prey most sought after. From time to time, the fish stopped in front of these potential preys and appeared to evaluate their availability for a preying attempt. Afterwards, the pufferfish either lunged/jumped out of the water to grab the prey, or exposed the head above the surface and forcefully expelled water from the mouth (spat) at the prey. Hunting success was about 15% for lunging and 10% for spitting. These observations raise to two the pufferfish species recorded to lunge/jump out of the water to secure a prey above water level, and add the Common Toadfish to the fish species that spit at a potential food item.