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.

Multi‐species foraging associations occur when one or more species forage together. However, these associations have not yet been studied during tool use in fishes. Observations were made of the graphic tuskfish Choerodon graphicus (De Vis 1885) in New Caledonia to determine whether other fishes attended it during tool‐use events. A new subtype of attendant associations, "scavenging at anvil", formed during 15 of 16 tool‐use events (94%). Six identifiable attendant families were observed: Acanthuridae (surgeonfishes; 3.7% of total attendant fishes), Balistidae (triggerfishes; 11.9%), Chaetodontidae (butterflyfishes; 9.6%), Labridae (wrasses; 19.3%), Pomacanthidae (angelfishes; 0.7%) and Pomacentridae (damselfishes; 54.8%). Anvil choice significantly influenced the assemblages of attendants (p = 1.982e‐10) but the size of C. graphicus did not (p = .4658). C. graphicus sometimes chased attendants but attendants did not behave aggressively towards C. graphicus or other attendants. C. graphicus appeared to be disadvantaged when attendants distracted it during tool use or scavenged its food. Attendants benefitted when they obtained food they could not otherwise access. Attendants may have responded to visual cues such as appearance, body movements and sand clouds, and auditory cues such as the "clack" sound made when a mollusc was struck on an anvil. Future studies should assess the importance of multi‐species fish foraging associations during tool use to the ecology of coral reefs.

Heteromorphic sex chromosomes (XY or ZW) present problems of gene dosage imbalance between the sexes, and with the autosomes. Mammalian X chromosome inactivation was long thought to imply a critical need for dosage compensation in vertebrates. However, the universal importance of sex chromosome dosage compensation was questioned by mRNA abundance measurements that demonstrated sex chromosome transcripts are neither balanced between the sexes or with autosomes in monotreme mammals or birds. Here, we demonstrate unbalanced mRNA levels of X genes in platypus males and females that correlate with differential loading of histone modifications, and confirm that transcripts of Z genes are unbalanced between males and females also in chicken. However, we found that in both species, median male to female protein abundance ratios were 1:1, implying an additional level of post-transcriptional control. We conclude that parity of sex chromosome output is achieved in birds, as well as all mammal groups, by a combination of transcriptional and post-transcriptional control, consistent with an essential role for sex chromosome dosage compensation in vertebrates.

Currently there are nine known examples of transmissible cancers in nature. They have been observed in domestic dog, Tasmanian devil, and six bivalve species. These tumours can overcome host immune defences and spread to other members of the same species. Non-coding RNAs (ncRNAs) are known to play roles in tumorigenesis and immune system evasion. Despite their potential importance in transmissible cancers, there have been no studies on ncRNA function in this context to date. Here, we present possible applications of the CRISPR/Cas system to study the RNA biology of transmissible cancers. Specifically, we explore how ncRNAs may play a role in the immortality and immune evasion ability of these tumours.

Tool use is a remarkable animal behaviour, and the investigation of this phenomenon in fishes is a relatively new and growing field. The graphic tuskfish Choerodon graphicus (De Vis 1885) has previously been documented using anvils but the extent and variability of this tool‐use behaviour remains poorly understood. In this study, we investigated whether C. graphicus breaks open crustaceans and/or sea urchins on anvils in different microhabitats and/or locations. We also inspected two previously identified anvils for evidence of long‐term anvil use. Three individual C. graphicus were observed breaking open sea urchins on dead coral anvils in a coral rubble microhabitat at Île aux Canards, New Caledonia. They produced visual and auditory cues while carrying out tool‐use behaviour and these cues often attracted attendant fishes. Notably, two anvils appeared to have been used by one or more tool‐using C. graphicus for years at Îlot Maître, New Caledonia. These findings suggest that tool‐use behaviour is both innate and learned and is a prey‐handling method of choice used by individuals that learn to specialise in large prey items from a few underutilised hard‐shelled prey species. Furthermore, the findings show that specific anvils can be used long‐term and also suggest that individual wrasses may carry out tool‐use behaviour long‐term. The study provides new insights into the feeding ecology and social behaviour of C. graphicus and underscores the need to further investigate the extent and variability of tool use in fishes.