The big dog

 Generally (manta cleaning stations excepted) big pelagic species are rare on the reefs inside Maldivian atolls. The big stuff lurks on the outside of the atolls where the reef walls plummet into the blue or holds in the gullies between islands riding the currents and waiting to see what the tides carry out. This dogtooth tuna was an exception. The dogtoothpart of the name explains itself but this actually isn't a true tuna.



In spite of its obviously tuna like appearance, Gymnosarda unicolor actually sits in a monotypic genus within the family Scombridae which is the fancy icthyology way of saying it's in the mackerel family alongside the tunas but is weird enough to sit on its own. It is more closely related to the small bonitos than the big true tuna in the genus Thunnus (bluefin, yellowfin etc). It really does have horrific teeth, these things will chew up fishing lures in a hurry (something they are increasingly gettin the opportunity to as anglers switch on to their power, fighting qualities and deliciousness).

 

It also features a number of classic tuna-style adaptations to pelagic living and predation. Wing like pectoral fins which will fold in completely, a big sickle tail for power and a caudal keel and finlets to do something hydrodynamic I don't understand. An imposter to the true tuna it may be but growing up to 288lbs (ie large man size) its a spectacular imposter. To contrast it with a true tuna check out this post.