Tool use by the graphic tuskfish Choerodon graphicus

Abstract

We describe how the graphic tuskfish Choerodon graphicus in New Caledonia uses rocks and coral heads as anvils to break open bivalves to obtain food. Video revealed that C. graphicus can make as many as 28 strikes on two anvils over 6 min in a single event. This example of tool use in fishes extends the behaviour taxonomically and geographically and supports the hypothesis that tool use may be widespread in wrasses, particularly those in the Choerodon genus.

Frequent visits to various anvils during tool use by the graphic tuskfish Choerodon graphicus (Labridae)

“…Out of 16 tool-use events, nine involved one anvil (56%), five involved two anvils (31%) and two involved three anvils (13%) ( Table 1). The finding that C. graphicus often uses multiple anvils is consistent with previous findings (Dunn, 2015;Pryor & Milton, 2019).…”

“…Anvil use in fishes occurs when a fish strikes a hard‐shelled prey item held in the mouth on a hard surface (anvil) in order to break it open. It is often carried out at preferred anvils (Paśko, 2010), as evidenced by broken shells (midden) (Jones et al ., 2011; Pryor & Milton, 2019) and by wrasses (Labridae) in different geographical locations (Supporting Information Table S1). It is not yet known whether it is an innate or learned behaviour.…”

“…evidenced by broken shells (midden) (Jones et al, 2011;Pryor & Milton, 2019) and by wrasses (Labridae) in different geographical locations (Supporting Information Table S1). It is not yet known whether it is an innate or learned behaviour.…”

“…(2 min, 44%), five took 120-240 s (2-4 min, 31%) and four took more than 240 s (4 min, 25%) ( Table 1) threats (Pryor & Milton, 2019), and the tenacity, skills and experience of the C. graphicus.…”

“…C. graphicus may have travelled from one anvil to another because it was looking for a more effective anvil (Pa sko, 2010), getting away from attendant fishes (Pryor & Milton, 2019) The only prey items brought to the anvils were different types of bivalve and gastropod molluscs (Supporting Information Figure S2 and Supporting Information Table S4). This finding is in accordance with previous findings (Bernardi, 2011;Coyer, 1995;Jones et al, 2011), however, it is possible that hermit crabs in gastropod shells were also brought to the anvils.…”