As they swim through the ocean away from human eyes, much of a shark\u2019s life is a mystery. But if you look closely, you can find clues about what they\u2019ve been through \u2013 in particular, through injuries, wounds and scars.\u00a0<\/p>\n
In a study, published in the journal\u00a0Frontiers in Marine Science<\/a> in 2025, researchers proposed a system to categorise what causes scars on great white sharks<\/a>.<\/p>\n “The scars and wounds seen on the sharks tell us about their interactions with each other, their environment, their prey and humans,\u201d said study author\u00a0Scot Anderson<\/a>\u00a0from the California White Shark Project<\/a>.<\/p>\n “Many of the scars are distinctive enough so they can be easily classified, such as\u00a0cookiecutter shark<\/a>\u00a0bite scars that are round full circle or a crescent moon mark when they don\u2019t remove the bite.\u201d<\/p>\n The California White Shark Project team shared a\u00a0video<\/a>\u00a0of a 16ft female great white shark with an unusual\u00a0scar on the top of her head. As the shark swims towards the camera, a perfect circle becomes visible on her head, almost like a dolphin’s blowhole. That’s the\u00a0iconic\u00a0plug of perfectly circular missing flesh that shows she was snacked on by a cookiecutter shark.<\/p>\n<\/p>\n Look closely: the round circle on the head of this female great white shark is a scar left from a cookiecutter shark\u00a0bite. Credit: California White Shark Project<\/p>\n \u201cCookiecutter wounds can tell us the white sharks get these marks during the ‘offshore phase’ off their migration as that is when they overlap habitat with cookiecutter sharks,\u201d said Anderson.\u00a0<\/p>\n Other types of scars might indicate\u00a0boat strikes<\/a>, defence wounds or a scrape from the rocks. It could even tell us if the sharks have been mating. Females might have “light impressions\u201d from bites from other sharks on their heads and pectoral fins from a mating encounter.\u00a0<\/p>\n “In many shark species, males must bite the female in order to hold on while copulating,\u201d he said. By the time his team observes these \u2018hold bites\u2019, they are \u201calways mostly or completely healed\u201d, Anderson said, suggesting that white sharks mate offshore \u2013 giving scientists another clue about where and how great whites reproduce<\/a>.\u00a0<\/p>\n \u201cIt is a line of evidence and a piece of the puzzle to try and determine where and when white sharks are mating, as we still do not know for sure,\u201d Anderson added.\u00a0<\/p>\n But to be able to interpret these clues \u2013 written in the scars on a shark\u2019s body \u2013 we need to be able to determine how the injury might have occurred. For example, the study suggests that \u201ca pattern of spaced dots\u201d shows where parasitic<\/a> copepods used to be attached to the animal, \u201ca series of parallel cuts with even spacing\u201d are the mark of a boat propeller, and a white \u201crope burn\u201d could be from entanglement in fishing gear.\u00a0<\/p>\n The paper proposed a “systematic classification system\u201d to help scientists determine the source of different types of scars, wounds and injuries.<\/p>\n This information, said Anderson, helps us learn even more about these magnificent animals: \u201cIt’s another puzzle piece that tells a story of what these white sharks experience.\u201d<\/p>\n