It's a bit ironic, but some ecologists actually call the world's largest species of parrotfish the "elephant of the sea." Now researchers have determined just how important - and harmful - this unusual fish is to the ocean's ecosystems.

A study published in the journal Conservation Biology details how the bumphead parrotfish (Bolbometopon muricatum) affects reefs in a complex mix of positive and negatives.

How could be a fish be bad for a coral reef ecosystem?

"These large parrotfish crunch off entire pieces of reef and audibly grind them up into sand in their pharyngeal mill - specialized teeth in the back of their throat," study author douglas McCauley explained in a statement. "You know bumpheads are near when you begin noticing branches lopped off stony corals and golflike divot scars marking the reef."

To conduct this latest ecological assessment, McCauley and his team took things back to the basics, conducting a tiring but worthwhile field study.

"We actually swam alongside bumphead parrotfish for close to six hours at a time, taking detailed data on what they ate and where they went," McCauley said. "It was one of the more exhausting but wonderful experiences I've had."

According to the study, these massive parrotfish can grow up to four feet long and weight more than 100 pounds. As one of the few major predators of coral, a single fish can consume more than two tons of live coral in a year.

That certainly isn't a good thing for declining coral populations, who can even be wiped out or smothered in one region by a large enough school of the fish. And yet the bumphead has long been deemed a protected species essential to ecosystems.

So what makes this unusual fish useful? Their predation of coral also haphazardly spreads coral chunks, which can resettle to grow elsewhere, much like birds unwittingly spread seed to new regions.

Bird comparisons aside, McCauley prefers to liken the bumphead to African elephants.

"African elephants are a vulnerable and imperiled species that can be agents of deforestation and reduce regional biodiversity," the experts explained. " Bumphead parrotfish are to coral reefs what elephants are to African savannas."

Their unusable appearance, complete with a massive bump-like nose, simply helps with the comparison.