By Sheril Kirshenbaum and Chris Mooney

The box jellyfish. A fascinating critter with powerful venom, this one’s not for the faint of heart.

Alternatively known as sea wasps and marine stingers, these animals serve up a frightening cocktail of toxins that attack the nervous system, heart, and skin. Generally they prey on fish and shrimp, but humans have also been killed as the result of encounters, which can lead to heart failure, shock, and drowning. Those who survive suffer through weeks of severe pain and scarring.

Box jellies are unique because they can move at up to four knots through the water, whereas most other jellyfish species simply drift. Their 24 eyes (six on each side of the bell) are made up of a lens, retina, iris and cornea, but with no central nervous system, scientists still aren’t sure how they process visual information. They have as many as 15 tentacles, which reach up to 10 feet in length and harbor an estimated 5,000 stinging cells each. Needless to say, box jellyfish are beautiful to watch…from a distance.

But these inverts came too close for comfort over the past weekend in Hawaii, when thousands arrived at Waikiki and Ala Moana beaches. Over 20 stings have been reported, and shores are temporarily closed in some areas. A reason for alarm? Probably not…yet. Such Hawaiian box jellyfish invasions are common events in the region, regularly occurring 7 to 11 days after a full-moon.

Still, it’s a reminder that jellyfish numbers around the world are on the rise. Earlier this year, The New York Times and The Economist reported exploding populations linked to global warming, overfishing and ocean pollution.

Wondering why you should care? Well, we’re all connected: oceans, land, and atmosphere. Humans are a single component of the vast array of biodiversity on the planet. What alters one species impacts the rest of system. So in other words, there’s a lot more to this story than a few extra jellyfish…