If a fish can pass the mark test

Subscribe to OpenChannels Newsletters

Would you like to subscribe to the OpenChannels Weekly Update or weekly Literature Update? Simply create a free OpenChannels Member Account and check the boxes for the Weekly Update and/or Literature Update newsletters.

For the week of 18 February 2019

Greetings OpenChannels Community Members,

PLOS Biology has published, If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals? "The ability to perceive and recognise a reflected mirror image as self (mirror self-recognition, MSR) is considered a hallmark of cognition across species. Although MSR has been reported in mammals and birds, it is not known to occur in any other major taxon. Potentially limiting our ability to test for MSR in other taxa is that the established assay, the mark test, requires that animals display contingency testing and self-directed behaviour. These behaviours may be difficult for humans to interpret in taxonomically divergent animals, especially those that lack the dexterity (or limbs) required to touch a mark. Here, we show that a fish, the cleaner wrasse Labroides dimidiatus, shows behaviour that may reasonably be interpreted as passing through all phases of the mark test: (i) social reactions towards the reflection, (ii) repeated idiosyncratic behaviours towards the mirror, and (iii) frequent observation of their reflection. When subsequently provided with a coloured tag in a modified mark test, fish attempt to remove the mark by scraping their body in the presence of a mirror but show no response towards transparent marks or to coloured marks in the absence of a mirror. This remarkable finding presents a challenge to our interpretation of the mark test—do we accept that these behavioural responses, which are taken as evidence of self-recognition in other species during the mark test, lead to the conclusion that fish are self-aware? Or do we rather decide that these behavioural patterns have a basis in a cognitive process other than self-recognition and that fish do not pass the mark test? If the former, what does this mean for our understanding of animal intelligence? If the latter, what does this mean for our application and interpretation of the mark test as a metric for animal cognitive abilities?"

As always, if we've missed anything, please feel free to let us know. You may simply reply to this message, or you may email Allie directly at: abrown [at] openchannels.org.

You can read everything (not just the free stuff) we have found this week at https://www.openchannels.org/literature-update/2019-02-20. Additionally, you can browse literature by the week we've added it at https://www.openchannels.org/literature-by-week.

Thank you for being part of the OpenChannels Community,
– Allie Brown, Raye Evrard, and the rest of the OpenChannels Team


OA: Berry, T. E. et al. Marine environmental DNA biomonitoring reveals seasonal patterns in biodiversity and identifies ecosystem responses to anomalous climatic events. PLOS Genetics 15, e1007943 (2019).

Ecosystem-based Management (EBM)

OA: Marshall, K. N., Koehn, L. E., Levin, P. S., Essington, T. E. & Jensen, O. P. Inclusion of ecosystem information in US fish stock assessments suggests progress toward ecosystem-based fisheries management. ICES Journal of Marine Science 76, 1 - 9 (2018).

Fisheries and Fisheries Management

OA: Gelcich, S., Reyes-Mendy, F. & Rios, M. A. Early assessments of marine governance transformations: insights and recommendations for implementing new fisheries management regimes. Ecology and Society 24, (2019).

Food for Thought

OA: Kohda, M. et al. If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals?. PLOS Biology 17, e3000021 (2019).

OA: Link, J. S. et al. Clarifying mandates for marine ecosystem-based management. ICES Journal of Marine Science 76, 41 - 44 (2018).

OA: Young, T. et al. Adaptation strategies of coastal fishing communities as species shift poleward. ICES Journal of Marine Science 76, 93 - 103 (2018).

Marine/Maritime Spatial Planning (MSP)

OA: de Vrees, L. Adaptive marine spatial planning in the Netherlands sector of the North Sea. Marine Policy (In Press). doi:10.1016/j.marpol.2019.01.007

Natural Sciences

OA: S Talbot, E., Widdicombe, S., Hauton, C. & Bruggeman, J. Adapting the dynamic energy budget (DEB) approach to include non-continuous growth (moulting) and provide better predictions of biological performance in crustaceans. ICES Journal of Marine Science 76, 192 - 205 (2018).


OA: Skirtun, M., Pilling, G. M., Reid, C. & Hampton, J. Trade-offs for the southern longline fishery in achieving a candidate South Pacific albacore target reference point. Marine Policy 100, 66 - 75 (2019).