In the end the team used two collection methods. Some eels were caught in hook-festooned funnel traps. "I've caught as many as 100 between four traps in a night." Reece says. Others were darted underwater. The biopsy dart, mounted on a seven-foot spear, takes a piece of tissue about the size of a pencil eraser, Reece says, and as a bonus dissuades the moray from molesting the diver.
His team collected 289 eels with only two injuries: a bite on a hand and one on a foot (of a documentary filmmaker who was tagging along with the scientists).
Less than one percent of the ocean consists of appropriate reef habitat, and adult reef fishes prefer to hang out at home, hiding from predators in the coral. How does it happen then, that the same species of fish can be found on widely separated barrier reefs or coral atolls?
The answer is that most reef fish have a juvenile stage called a pelagic (oceanic) larva that lets them disperse over open ocean.
The larvae either swim or drift in surface currents, sometimes modifying their buoyancy to use both surface and deep currents, writes Reece in the Journal of Heredity.
So important is this wandering phase that some biologists have proposed as a rule of thumb that the longer-lived the larvae (the longer the "pelagic duration") the more genetically homogeneous the species is likely to be.
Moray eels provide an ideal test of this idea. They are poor swimmers as juveniles, and adults stick to a few square meters of reef. On the other hand, they have an extremely long-lived pelagic form.
Whereas another fish's pelagic larvae might live for a month or two, moray eel larvae can persist for several months or even years.
The slender, elongate larva, called a leptocephalus, is one of the simplest self-sustainin
|Contact: Diana Lutz|
Washington University in St. Louis