Uncovering the mysteries of the Galapagos bullhead shark

Can you tell us about the Galapagos Bullhead Shark Project and how you came to be involved? 

SL: The Galapagos Bullhead Shark Project is a long-term initiative focused on studying the demographics and distribution of this little-known species. There is currently very limited information about the species’ biology and ecology, as well as the challenges it may face in such a unique ecosystem as Galapagos. 

I got involved in the project while looking for a Master’s thesis topic for my Tropical Ecology and Conservation programme. I wanted something that would integrate my veterinary background with applied conservation research. I started reaching out to people at my university about marine fauna projects, hoping to find a collaborative and engaging research team. That’s when I learned about this project and contacted Max. Together we have been studying the species’ reproduction using non-lethal techniques such as ultrasound evaluations and reproductive hormone levels. 

DS: I became involved in the Galapagos Bullhead Shark Project while looking for a tutor for my final year thesis in Environmental Management at the Universidad San Francisco de Quito. I contacted Maximilian Hirschfeld and he explained his research on bullhead sharks in detail and invited me to participate and contribute to the Project. Despite having limited knowledge of this species at the beginning of my research, I jumped at the opportunity to study this little-known shark species in Galapagos. This experience has not only enriched my academic training but has also allowed me to contribute to the knowledge and conservation of the unique biodiversity of Galapagos.

What inspired you to work in Galapagos and focus your research on Galapagos bullhead sharks? 

MH: It had long been a dream of mine to visit Galapagos when I was studying to become a marine ecologist. I first came to Ecuador in 2005, visiting the alley of volcanoes and volunteering in the Amazon jungle. But with little in my pockets, thefamous Archipelago still seemed far from reach, so I promised to return. Since 2010, I have studied and worked on the Islands, focusing my research on sharks.  

The first time I saw one of the small but magnificent bullhead sharks was diving off the tip of Isabela island in 2012. Determined to find out more about this little-known species, I started to interview dive guides, national park rangers and fishermen. One answer that still sticks in my mind and highlights my fascination for this species is “Max, I think this shark only exists in your imagination.” 

This is how little we knew about this species that even seasoned divers had never laid eyes on a specimen. This is where the bullhead shark treasure hunt began. Together with Galapagos Conservation Trust, the Galapagos National Park Directorate and the participation of citizen scientists we now have a much better understanding of where to find this species and we are getting closer to finding out where their critical habitats for reproduction are and if the Galapagos population has a unique genetic fingerprint. 

SL: During my first visit to Galapagos, I was struck by how incredible the place was and I knew I wanted to learn more and contribute to its conservation. I feel so lucky to be able to work in the Archipelago. As for the Galapagos bullhead sharks, being able to see them up close and study them is like having a window into another way of existing, one that has been here longer than us. I think a big part of what drives me is curiosity, the need to understand them and knowing that what we discover about them can also be applied to similar species. 

Can you tell us more about the environmental education work you have been doing on Floreana and why you think it is important to engage the local community in shark conservation? 

DS: My work on Floreana focused on raising awareness of the ecological importance of Galapagos bullhead sharks among students. To do this, we ran a workshop on the island with activities designed for children and young people. 

In preparation for the workshop, we developed several teaching materials and interactive activities. We carried out a presentation on the species using infographics and posters provided by the Galapagos Science Center. We also brought illustrated stories about the local fauna and donated them to the school. In addition, we showed photos and videos of the bullhead shark habitat which sparked great enthusiasm from the children. 

Involving the local community in shark conservation is essential as it promotes respect for biodiversity and fosters a sense of responsibility towards the protection of marine ecosystems in Galapagos. 

MH: The small population of people who live on Floreana island has received much less attention from conservation outreach and education efforts in comparison to the bigger towns on San Cristobal and Santa Cruz. For the 120 people living on Floreana there is only one school. Many of the kids, despite living an island life, have had little chance to explore the underwater world at their doorstep. We believe there is great potential here for fostering the next generation of conservationists, particularly for sharks. Last year we partnered with the local school to actively involve kids across all age groups to learn more about Galapagos bullhead sharks and the work we do. Next time we plan to bring them even closer to the sharks by including them in a simulation of a day in the field.

What are some of the challenges you face when conducting fieldwork? 

SL: Working in a protected area requires careful planning and consideration to ensure that our methods do not disrupt the environment or wildlife. This means using non-invasive techniques which sometimes limit the data we can collect compared to traditional methods. 

One of the biggest challenges is the unpredictability of nature. Weather conditions can change unexpectedly, affecting access to study areas or the ability to collect data. Fieldwork often demands flexibility and patience. Unexpected situations, such as equipment malfunctions or changes in animal behaviour, can challenge our timelines and research goals which require adaptability. There are days when we can’t find any Galapagos bullhead sharks as they camouflage very well and hide among the rocks. Over time, we have gotten better at predicting where they might be, almost as if we are learning to think like sharks!

MH: Bullhead sharks are masters of disguise. They love cold water and the darkness that comes with the night. Our fieldwork takes us to some of the most remote places in Galapagos, where we explore caves and crevices of the underwater world. Diving at night in the search for bullheads is like entering a new world. The sharks themselves are well-adapted to this lifestyle, giving them their otherworldly look and cat-like eyes. Working in such conditions requires working together tightly as a team. Everything has to run like clockwork to ensure the safety of the divers and the sharks.  

DS: One of the main challenges I faced during fieldwork was learning the freediving techniques needed to dive and search for bullhead sharks among the rocks, crevices and caves near the seabed. This method requires excellent physical fitness and significant mental concentration. Adverse weather conditions, such as heavy waves and reduced visibility, complicated our searches for sharks. In addition, many sharks were found in different locations close to coastal areas, which meant that we had to swim around the perimeter of islands in search of them. These experiences highlight the importance of the physical and mental preparation needed for marine research in challenging environments such as the Galapagos Islands.

Can you share a surprising fact about Galapagos bullhead sharks?

DS: One of the most striking observations about the Galapagos bullhead shark is the variety in their skin colouration. Although generally greyish or brownish tones with large spots in a leopard pattern, individuals have been observed in shades ranging from dark brown to light brown. In addition, the pattern of black spots on their ventral side also differs between individuals. As for their diet, they are known to feed on molluscs, crabs and small invertebrates. However, observations of bullhead sharks close to lobsters and sea urchins suggest that these species may also form part of their diet. These differences in colouration and feeding habits highlight the need for further studies to better understand the biology and ecology of this species in Galapagos.

SL: A surprising fact about Galapagos bullhead sharks is that they belong to a very ancient group of sharks called Heterodontiformes, which dates back to the Jurassic period. Their ancestors were already quite similar to modern bullhead sharks and it’s believed that this group spread across the ocean when the supercontinent Pangaea broke apart millions of years ago. It’s almost as if time passes differently for them, preserving traits from their ancient ancestors. Their reproductive method, known as oviparity, is one of the most ancient forms of reproduction. Oviparous species, like bullhead sharks, lay eggs that develop outside the mother’s body. This method is considered primitive and is typical of early fish evolution. It’s amazing to think how these ancient creatures have survived through time and continue to thrive in places like Galapagos.

MH: Everything about this species is fascinating and surprising. Evolution has separated the bullhead shark and the entire genus Heterodontus from other shark species millions of years ago. All species of bullhead sharks lay eggs in the shape of a large leathery spiral, which could have easily inspired popular sci-fi movies. While Galapagos bullhead sharks are even smaller than most of their sister species, they have many tools to defend themselves. They have pointy spines in front of their dorsal fins (on their backs) and their skin is made of large scales, called dermal denticles, made of the same material as teeth. When inspected up close, these denticles resemble a field of flowers.