Mirrors have disclosed something new about manta lights- and it reflects severely on us

Humans attain huge employ of marine vertebrates, but manta rays may pass the self-awareness test and other fish potentially could too. Ethically, where does that leave us?

As a shark biologist, I enjoy nothing more than going with sharks in the wild. However, I realise it’s an immense privilege to do this as part of my work- and that for the vast majority of people experiencing the underwater world in such a way is simply not possible.

Nevertheless, even without the aid of an air tank humans interact with fish on many levels and in greater numbers than they do with mammals and birds. A review published by the publication Animal Cognition in 2014 by Culum Brown, an associate professor at Macquarie University, Sydney, expressed the view that fish are one of the vertebrate taxa most highly utilised by humen. But despite the fact because this is harvested from wild stocks as part of global fishing industries, grown under intensive aquaculture conditions, are the most common pet and are widely used for scientific research, fish are seldom afforded the same level of compassion or welfare as warm-blooded vertebrates.

As Brown highlights in his review, part of the problem is the large gap between people’s perception of fish intelligence and the scientific reality. This is an important issue because public perception guides government policy. The perception of an animal’s intelligence often drives our decision on whether or not to include them in our moral circle. From a welfare view, most researchers was proposed that if an animal is sentient, then it can most likely suffer and should therefore be offered some form of formal protection.

There has been a debate about fish welfare for decades which centres on the question of whether they are sentient or conscious. In other terms do fish have an awareness of internal and external stimulations and do they possess the capacities for self-recognition/ awareness?

In 2016 a study was published by Dr Csilla Ari and Dr Dominic D’Agostino on giant manta rays ( Manta birostris ), which explored the notion of whether these elasmobranchs could be classed as self-aware. Giant mantas have the largest brain of all fish species, as described by Ari in 2011; they often form large feeding aggregations, indicating complex social interactions and are often referred to as intelligent. They were therefore seen as ideal nominees for investigating self-awareness.

For the study Ari and D’Agostino employed the mirror self-recognition test( MSR ), a technique originally developed by psychologist Gordon Gallup in 1970 as a way is required to determine whether a non-human animal has the ability to recognise itself. The MSR is considered a dependable behavioural index and has been used to prove self-awareness in the great apes( bonobos, chimpanzees, orangutans and gorillas ), bottlenose dolphins, Eurasian magpies and Asian elephants.

In order to ascertain whether an animal can pass this test, researchers first uncover the animals to a mirror. If they indicate social answers they likely perceived their mirror image as another person and did not recognise themselves in the mirror. If they present repetitive and unusual movements they are considered potentially capable of passing the test. In the next phase researchers usually place a mark on the animal’s body( eg paint ). They then find what happens when the marked animal is placed in front of a mirror.

Animals that pass the test are generally adjust their positions so that they can get a better look at the new mark on their body, and may even touch or try to move it. Typically, they pay much more attention to the part of their body that bears a new marking.

Whilst no fish species has so far passed this type of exam, surveys have shown fish respond to their mirror images differently than they do to members of the same species( Desjardins and Fenald 2010 and Balzarini et al 2014 ). It is, however, worth mentioning that for some species of fish responses to olfactory cues may be a more appropriate test of self-recognition as opposed to the visually-biased MSR. A survey by Thunken et al in 2009 investigated cave cichlids and discovered they had the ability to recognise their own olfactory cues.

In the Ari and D’Agostino study, due to the difficulties associated with marking a manta ray, observations were induced instead in its relationship with mirror exposure merely. Results showed that the Mantas exhibited unusual and highly repetitive movements, exploratory, contingency checking and self-directed behaviour when exposed to second-hand mirror. More specifically they gave selective attention to the mirror by displaying significantly more repetition movements( very frequent cephalic fin movements) than under control conditions( observations constructed when no mirror was present) as well as several unusual behaviours, such as reveal and observing their underside in the mirror and bubble blowing, similar to what was observed when bottlenose dolphins were exposed to a mirror.

Mantas are also able to change their colour, rapidly increasing the intensity of their white differentiates when a new individual approaches( Ari 2014 ). This was not find when they were exposed to second-hand mirror, making it reasonable to assume that the animals did not perceive their mirror image as a new someone and that the observed behaviours were not part of normal social interaction.

Overall, Ari and D’Agostino’s study provides evidence for behavioural answers known to be prerequisites for self-awareness and which have been used by other researchers to confirm self-recognition in ape species. Given that self-aware species are known to exhibit complex social behaviour, cooperative behaviour and empathic behaviour, this experiment and another mentioned surveys shine a light on the health risks cognitive capabilities of fish and calls into question the ethical practises of current fisheries. The International Union for the Conservation of Nature recognises the giant manta light as a vulnerable species, with a lessening current population trend. Protection in some regions does exist and this species is listed on the Convention on International Trade in Endangered Species Appendix II, which restricts their trade. Despite this, up to 1,000 giant mantas are thought to be harvested from specific locations every year for their meat and gill rakers, the latter being traded as Chinese medicine.

I have been fortunate enough to with mantas in the Philippines and Maldives. Having considered these wonderful creatures at close quarters, I hope that analyzes such as the one described here will encourage farther research and ultimately influence much-needed further protective legislation and policy in the near future.

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References

Brown C( 2015 ), Fish Intelligence, Sentience and Ethics, Animal Cognition, 18: 1.

Ari C and D’Agostino DP( 2016 ), Contingency Checking and Self-Directed Behaviors in Giant Manta Rays: Do Elasmobranchs Have Self-awareness ? Journal of Ethology, 34: 167.

Ari C( 2011 ), Encephalization and Brain Organization of Mobulid Rays( Myliobatiformes, Elasmobranchii) with Ecological Perspectives, The Open Anatomy Journal, 6: 1-13.

Gallup, G( 1970) Chimpanzees: Self-Recognition, Science, 167, 3914, 86 -8 7.

Westergaard GC and Hyatt, CW( 1994 ), The Responses of Bonobos ( Pan paniscus ) to Their Mirror Image: Proof of Self-recognition. Human Evolution. 9: 273 -2 79.

Paola Cavalieri and Peter Singer( eds .), The Great Ape Project New York: St. Martin’s Griffin, 1993, pp. 58 -7 7.

Robert S( 1986 ), Ontogeny of Mirror Behaviour in Two Species of Great Ape. American Journal of Primatology. 10( 2) 109 -1 17.

Marten K and Psarakos S( 1994 ), Evidence of Self-Awareness in the Bottlenose Dolphin ( Tursiops truncatus ), in ST Parker, RW Mitchell and ML Boccia( eds ), Self-Awareness in Animals and Human: Developmental Views( pp. 361 -3 79 ).

Prior H, Schwarz A, Gunturkun O( 2008 ), Mirror-induced Behavior in the Magpie ( Pica pica ): Evidence of Self-recognition, PLoS Biol 6 (8 ): e202.

Plotnick JM, De Waal FBM, Reiss D( 2006 ), Self-Recognition in an Asian Elephant, PNAS, 103( 45 ), 17053 -1 7057.

Desjardins J, Fenald, K.( 2010 ), What do Fish Make of Mirror Images ? The Royal Society Biology Letters.

Balzarini V, Taborsky M, Wanner S, Koch F, Frommen J( 2014 ), Mirror, Mirror on the Wall: The Predictive Value of Mirror Tests for Measuring Aggression in Fish, Behavioural Ecology and Sociobiology 68: 871.

Thunken T, Waltschyk N, Bakker TCM, Kullmann H( 2009 ), Olfactory Self-Recognition in a Cichlid Fish. Animal Cognition 12: 717.

Ari C( 2014 ), Rapid Coloration Changes of Manta Rays( Mobulidae ), Biological Journal of the Linnean Society 113( 1) 180-193.

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