A Guide to Understanding Shark Behavior

Written by Emily Padden

Writing Intern Learn More About Emily

January 6, 2023

Galeophobia or the fear of sharks (Selachimorpha) and the misconceptions of their “bloodthirsty” behavior have been circulating since the 18th century. Beginning with Carl Linneaus’ species description depicting armor-like teeth and aggressive tendencies, the vilification of sharks has only grown over time. Media misrepresentation and government initiatives to eliminate shark populations (such as netting and widespread depth charge deployment) have prevented the development of a better understanding of sharks and their behavior[1]Neff, C. & Hueter, R. Science, policy, and the public discourse of shark “attack”: a proposal for reclassifying human–shark interactions. J Environ Stud Sci 3, 65–73 (2013)..

Understanding Agonistic Shark Behavior

The best way to overcome common misconceptions about sharks is to educate ourselves on identifying different behavioral characteristics they display, especially aggressive or agonistic ones. Agonistic behavior is a class of behavioral actions exhibited when an organism feels threatened or is preparing to react to a situation[2] Ritter, E. K. & Godknecht, A. J. Agonistic Displays in the Blacktip Shark (Carcharhinus limbatus). Copeia 2000, 282–284 (2000).. By understanding the agonistic indicators in shark species, those participating in ocean recreation can better prepare for any possible encounters. Understanding agonistic indicators will also help when classifying these encounters, demonstrating that sharks do not always take a reactive approach toward human beings. Agonistic displays are classified through movement, physical displays, or both. Common physical displays in most shark species include a prominently raised snout, downward bending of the pectoral fins, an arched back, and rapid opening and closing of the mouth[3]Martin, R. A. A review of shark agonistic displays: comparison of display features and implications for shark–human interactions. Marine and Freshwater Behaviour and Physiology 40, 3–34 (2007).. This behavior is accompanied by movements such as exaggerated side-to-side or parallel swimming, and rolling and/or spiral looping. Having a somewhat defined set of agonistic behavioral indicators provides a basis for identifying why and when a shark may act out. Even if we are unable to perfectly classify all agonistic indicators, knowing that sharks exhibit specific behaviors before “acting aggressively” helps diminish negative stereotypes directed towards them [4]Rodrigues-Filho, L. F. & Sales, J. B. D. L. Chondrichthyes: Multidisciplinary Approach. (BoD – Books on Demand, 2017).[5]NELSON, D. R. On the Field Study of Shark Behavior. American Zoologist 17, 501–507 (1977).

Figure 1: (a) non-display, (b) mild display, (c) strong display, (d) feeding posture. BA = back arch, PD = pectoral depression, SR = snout raise[6]Martin, R. A. A review of shark agonistic displays: comparison of display features and implications for shark–human interactions. Marine and Freshwater Behaviour and Physiology 40, 3–34 (2007.

So, You’ve Encountered a Shark, Now What? 

Despite sharks often signaling before acting, it is still important to understand what to do when faced with an aggravated shark. They are wild animals and we must treat them as such. You wouldn’t want to approach an angry bear or moose, just like you wouldn’t want to approach a shark displaying agonistic behaviors. The following steps provide an outline of guidance if you find yourself faced with an agitated shark[7]Gibbs, L. & Warren, A. Transforming shark hazard policy: Learning from ocean-users and shark encounter in Western Australia. Marine Policy 58, 116–124 (2015)..

  1. Face the shark and maintain eye contact.
  2. Do not touch, approach, or photograph a shark displaying agonistic behaviors or indicators, you should be focused on giving the animal plenty of space.
  3. If you are carrying speared or caught fish and other marine animals, discard them. This will help to disassociate you from a potential food source.
  4. Back away from the displaying shark, using smooth purposeful movements such as long strokes and unhurried kicks. Try to avoid jerky or frantic movements; this will allow the shark to leave the area if feeling threatened.
  5. Remain on the bottom, with your back toward a reef, wreck, or large object. In the event you are in open water, return to your boat, or move as far away from the shark as you are able.
  6. Return to your exit point and exit the water in a calm but purposeful manner, moving quickly but not erratically. 
  7. When surfacing in areas of open water, check your surroundings, above and below the water in case the shark follows you.
  8. If the shark follows, use any available object to deter the animal, or to create more space between you and it; try to avoid using your bare hands, as the shark’s rough skin or teeth may cause injury.

Understanding the Types of Shark Encounters

There are many types of shark encounters and ways in which sharks generally react to humans. Possessing knowledge of how a shark may approach provides a more significant basis for understanding how to react to that situation. Risk of injury is possible when dealing with sharks, but understanding why or how an encounter may occur is the best way to maintain your safety.

  1. Hit-and-run encounters are the most common and generally occur in shallow waters. This is usually a result of a juvenile shark’s ineffective prey strategy, rather than aggressive behavior. 
  2. The “sneak attack” occurs when the swimmer or diver did not see the shark before the encounter, while the shark may have noticed and watched the swimmer before approaching. This usually occurs in deep water where sharks can remain out of sight, and are less accustomed to human interaction.
  3. Bump and bite is the final main category of shark encounters. This scenario is classified as a shark circling and repeatedly bumping into its intended target before biting. Just like the “sneak attack” encounter, this largely occurs in deep open water and is quite rare[8]Lemahieu, A. et al. Human-shark interactions: The case study of Reunion island in the south-west Indian Ocean. Ocean & Coastal Management 136, 73–82 (2017)..

Although it can be intimidating to imagine being approached by a shark, understanding the encounters helps us to avoid them more successfully. Swimming or diving carries an inherent risk of encountering a shark, so if you intend on participating in these activities, you must acknowledge the potential. Being mindful and aware of your surroundings eliminates a lot of your risk. Studies done on different shark encounters demonstrated that most sharks displayed some degree of agonistic tendencies before approaching their “target,” so “know before you go” and educate yourself on shark behavior before entering a shark’s habitat [9]Caldicott, D. G. E., Mahajani, R. & Kuhn, M. The anatomy of a shark attack: a case report and review of the literature. Injury 32, 445–453 (2001).[10]The behavioural biology of marine fishes and sharks. The Behavioural Biology of Zoo Animals 253–268 (CRC Press, 2022). doi:10.1201/9781003208471-21..

The Importance of Understanding Sharks

Understanding sharks and how they interact with prey and humans is crucial not only to our safety when participating in marine recreation but also for conservation efforts. Humans are less likely to promote the conservation of organisms they are afraid of or deem pesky and dangerous[11]Mourier, J., Vercelloni, J. & Planes, S. Evidence of social communities in a spatially structured network of a free-ranging shark species. Animal Behaviour 83, 389–401 (2012).[12]Friedrich, L. A., Jefferson, R. & Glegg, G. Public perceptions of sharks: Gathering support for shark conservation. Marine Policy 47, 1–7 (2014).. The depiction of sharks as “bloodthirsty man-eaters,” not only mislabels them but takes away the protection they require and deserve as crucial members of marine ecosystems and food chains[13]Official Australian Shark Facts & Ocean Ecosystems. Shark Champions https://sharkchampions.org.au/issue/shark-ecosystem/.. By continuing our education on sharks and shark behavior, we can make the ocean a safer place for people to enjoy, and for sharks to live. For a species that has survived 450 million years on Earth, it is our job to ensure they receive the attention and protection they deserve without the harmful assumptions and stereotypes placed on their behavior[14]Shark evolution: a 450 million year timeline. https://www.nhm.ac.uk/discover/shark-evolution-a-450-million-year-timeline.html..

Emily Padden
Emily Padden

Writing Intern

Learn More About Emily

References

References
1 Neff, C. & Hueter, R. Science, policy, and the public discourse of shark “attack”: a proposal for reclassifying human–shark interactions. J Environ Stud Sci 3, 65–73 (2013).
2  Ritter, E. K. & Godknecht, A. J. Agonistic Displays in the Blacktip Shark (Carcharhinus limbatus). Copeia 2000, 282–284 (2000).
3 Martin, R. A. A review of shark agonistic displays: comparison of display features and implications for shark–human interactions. Marine and Freshwater Behaviour and Physiology 40, 3–34 (2007).
4 Rodrigues-Filho, L. F. & Sales, J. B. D. L. Chondrichthyes: Multidisciplinary Approach. (BoD – Books on Demand, 2017).
5 NELSON, D. R. On the Field Study of Shark Behavior. American Zoologist 17, 501–507 (1977).
6 Martin, R. A. A review of shark agonistic displays: comparison of display features and implications for shark–human interactions. Marine and Freshwater Behaviour and Physiology 40, 3–34 (2007
7 Gibbs, L. & Warren, A. Transforming shark hazard policy: Learning from ocean-users and shark encounter in Western Australia. Marine Policy 58, 116–124 (2015).
8 Lemahieu, A. et al. Human-shark interactions: The case study of Reunion island in the south-west Indian Ocean. Ocean & Coastal Management 136, 73–82 (2017).
9 Caldicott, D. G. E., Mahajani, R. & Kuhn, M. The anatomy of a shark attack: a case report and review of the literature. Injury 32, 445–453 (2001).
10 The behavioural biology of marine fishes and sharks. The Behavioural Biology of Zoo Animals 253–268 (CRC Press, 2022). doi:10.1201/9781003208471-21.
11 Mourier, J., Vercelloni, J. & Planes, S. Evidence of social communities in a spatially structured network of a free-ranging shark species. Animal Behaviour 83, 389–401 (2012).
12 Friedrich, L. A., Jefferson, R. & Glegg, G. Public perceptions of sharks: Gathering support for shark conservation. Marine Policy 47, 1–7 (2014).
13 Official Australian Shark Facts & Ocean Ecosystems. Shark Champions https://sharkchampions.org.au/issue/shark-ecosystem/.
14 Shark evolution: a 450 million year timeline. https://www.nhm.ac.uk/discover/shark-evolution-a-450-million-year-timeline.html.

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