Tenerife is home to innumerable underwater species. The divers here are very lucky as they have the possibility to observe a diversified aquatic environment. However, did you know that one of these species is actually not welcome in Tenerife waters? It is the long-spined black sea urchin, that is an invasive species in Tenerife. Indeed, this kind of urchins are not originally from the Canary Islands, they were brought here by humans. What does invasive species mean? As any other animal in the world, urchins live in a certain ecosystem where they have natural strong and weak sides (like competitive species, natural predators) and in these conditions, their number is held at a normal amount. They don’t overgrow and they don’t die too quickly because all their environment is interconnected in a way that all organisms are in equilibrium. This is valid for all species in the world. So, what happens when you bring a species in an environment that is not its natural ecosystem? Long-spined black sea urchins brought to Tenerife give an example how these organisms get more advantages than weak points because they don’t have natural predators. This means that their number can grow without limits and they eventually overcome other local populations. Moreover, they can bring bacteria that causes diseases to other organisms. That is why we can sometimes see places with overabundance of sea urchins and none of other aquatic life. This is an important issue because the other species need to be protected against that human-made phenomenon. For this reason, local authorities and divers of the island are working alongside to kill long-spined black sea urchins. This is a difficult task as sea urchins have overflowed all coasts of the Canary islands. But as ambassadors of the Ocean, we all try to protect the local species of the island. We have to be carefull though because other sea urchins species are not invasive and should not be killed (e.g. normal black sea urchin, purple sea urchin etc.).