Reports of this phenomenon have come from as widespread as Florida to Australia’s Great Barrier Reef. A sixbar wrasse in an aquarium was even observed using a rock as a tool.
Witnesses say there are a number of steps involved in the process: the wrasse will excavate sand to get the shell out from hiding; then swim around looking for an appropriate location to crack the shell before using the rock to smash the shell to reach the meat inside.
Impressive methodology for a wrasse to implement; considering it was only discovered that chimpanzees used tools in the 1960s (a shocking revelation at the time). Since then, many animals have been observed using tools; various primates, birds, dolphin, elephant, etc. Yet, it is fascinating to hear of a small reef fish using such advanced thought process.
Humans spend short intervals underwater observing fish behavior; it could be that all species of wrasse use tools (as opposed to only the yellowhead, blackspot tuskfish, or sixbar wrasse, that have been witnessed). And therefore, more likely than not that there are other examples of fish using tools that have not yet been observed.
New discoveries such as this are crucial to understanding the ocean, as we find more similarities between humans and the unknown watery abyss. It becomes impossible to deny how interconnected (related) all species on this planet really are once we focus on the similarities instead of the unknown.