Sharks generally have a reputation as remarkable sea predators. However, the laws that govern the food web are not always what we think they are. For these tourists on an expedition, witnessing a scene of sea lions attacking small thresher sharks was surely a shock.The crew had departed off the coast of Newport Beach in California to observe some marine mammals. Alongside the pictures of whales that they certainly took along the way, the people aboard would take away one thing from this journey: you don’t joke with sea lions.The passengers saw five of them hunting several young thresher sharks. ‘It was completely mad,’ confesses Slater Moore, a photographer and member of the ship’s crew, to The Huffington Post. Remarkable imagesThe man took this unmissable opportunity to capture images of this scene and to set off his drone a few metres above the scene of the hunt. The subsequent shots and clips document this unsuspected phenomenon with accuracy.'Everyone on the boat was completely bewildered,' says Slater Moore. 'Nobody was expecting that these sharks would be the prey of another species, let alone the prey of a sea lion.'According to Chris Lowe, Director of the Shark Lab at California State University, this kind of behaviour is widespread. He explains: ‘People don’t think that marine mammals can eat sharks, but it’s actually pretty common.’Opportunistic predatorsSea lions are actually opportunistic predators who look for their food based on how easy it is to access. They can prey on squid, herring, or even small sharks, depending on what they find in their midst. The more inexperienced and young the latter are, the more they represents an ideal target for sea lions.‘After thresher sharks are born, they get no training. They don’t really know how to avoid predators yet,’ Lowe explains.Although sea lions seem to be merciless hunters when faced with these small sharks, they're not the uncontested rulers of the ocean. Sea lions in their turn are prey for some more imposing species like orcas and great white sharks.Check out the video above to see the shocking scenes for yourself!