Info Sharks play an essential role in the marine ecosystem, but their existence is threatened on a global scale as a result of human activity. We can assure the conservation of these animals for the future. Biology Sharks (and the related rays and skates) are cartilaginous fish who’s entire skeleton is made up of cartilage. Species The Dutch Caribbean islands are home to an array of large shark species, such as tiger sharks and hammerheads. Threats The two main factors posing a threat to shark populations are fisheries and the significant loss of habitat. Conservation Thankfully, more and more people are learning about the plight of shark populations.