About This Project

How many sharks should there be on Caribbean reefs? Despite evidence suggesting that sharks once existed in numbers unheard of today, this critical question remains unanswered. We discovered that sharks leave a record of their presence in the form of dermal denticles, the tiny, tooth-like scales lining their skin, preserved in reef sediments. We are now pioneering denticles as an ecological tool to reconstruct pre-human shark baselines and supplement surveys on modern reefs.

Ask the Scientists

What is the context of this research?

You can think of denticles as 'skin teeth.' They're the reason why shark skin feels smooth in one direction and rough in the other. Denticles play a variety of roles, ranging from hydrodynamics to protection. Consequently, they are quite morphologically diverse, and their form is highly linked to shark ecology. They've even inspired biomimicry designs, including Speedo's FastSkin swimsuit.

Denticles are continually shed by sharks, and we've found them to be well-preserved on both modern and fossil reefs. They allow us to paint a long-term picture of the number and types of sharks inhabiting a reef even if we can't see them (or if they're long gone). Our study is the first of its kind to explore denticles as a 'window' into pristine shark communities in the recent past.

What is the significance of this project?

Sharks are critical players in healthy coral reef ecosystems. However, they are notoriously difficult to census given their rarity and elusive habits. On many occasions, they are not even reported in surveys. How can we protect something that we seldom see? Additionally, pre-human shark baselines are essentially nonexistent, further hampering conservation efforts. With our perception of ‘pristine’ shifting over time, it is difficult to set management targets and assess recovery since we don’t have a very good grasp on the magnitude of shark declines. However, by revealing the abundance and diversity of sharks currently living on reefs as well as the status of shark communities in the past, our project has the potential to inform more realistic region-specific shark conservation goals.

What are the goals of the project?

The goal of our project is to develop dermal denticles as a new tool to assess whether shifts have occurred in shark communities over time and space in the Caribbean across the timeline of human interaction with the ocean. We will accomplish this by first ground truthing the denticle record (extracted from reef sediments we collect) with newly-available shark survey data from Baited Remote Underwater Video on Curaçao. Then, we will explore patchiness in denticle assemblages across reef habitats and what it can tell us about sharks’ habitat use. Finally, we will compare denticle assemblages on Curaçao with our existing denticle collections from modern and fossil reefs in Panama and the Dominican Republic to evaluate spatial and temporal variation in the Caribbean.