Tarpons and Ladyfish: Order Elopiformes

The order Elopiformes is a relatively small order made up of some very popular sport fish, the tarpons, ladyfish and tendpounders. One might not guess on first glance, but they are closely related to the eels. In fact, elopiform fishes look more like herring as adults. As larvae however, they look just like eel larvae. The have what is known as leptocephalus larvae.

Leptocephalic larvae

Tarpon, ten pounders and ladyfish have several stages of developement. The first stage is a leptocephalus larvae that is long and flattened. In fact, these larvae can be quite large - up to 300mm! As the young develope they get smaller before growing to the size of a tarpon.

In the day, leptocephalic larvae are found deeper in the water column - usually below about 100 meters. They migrate upwards at night to feed on marine snow. Until recently, marine biologists had no idea what they fed on.

Air breathing

Another unique characteristic of elopiform fishes is that they are obligate air breathers. That means they have to breath air from the surface or they'll die. Air breathing is made possible through their swim bladder. Like other primative rayfinned fish, elopiforms have vascularized swim bladders.