Overly Successful Invaders

Far from their natural habitat, two species of animal are wreaking havoc on environments that have no natural defenses, and the results have been devastating. In a cruel twist, each of the animals has a name that is both cool and simple.

Fire Ants

Originally from the Amazon, these ants caught a ride in South American ballast holds and once dumped, used their amazing ability to form colony-sized rafts and floated onto the American shores in Mobile Alabama.

Capable of producing nine million new ants a day, colonies tend to balloon to forty-million and live in in enormous underground labyrinths that they excavate. The tunnels keep the ants insulated from both heat and cold, and stretch down to the water table, so the colonies are also resistant to drought.

Fire ants don't bite in the sense that they break the skin with a painful mandible-strike. Their mandibles are quite strong, but they use them to grip whatever it is they're going to attack, and then they use their stinger on the end of their abdomen. Since it doesn't detach, they can make multiple strikes, with each one delivering venom.

With no natural predators, fire ants have started their slow march away from Alabama towards points east, west, and north. They are essentially unstoppable. Scientists have been working on how to stop the invasion...and then gave that up for the possibly possible goal of controlling the numbers. In this they found a glimmer of hope.

It turns out there's a specie of parasitic fly that only preys of fire ants. The reason the ants can make a raft is because of a substance in their exoskeletons, and it is for this hard substance that these flies have developed weaponry. The fly attacks, lays a single egg in the thorax of the ant, the egg grows into a maggot, migrates to the ant's skull. It takes over the ant's brain, eventually releases an enzyme that decapitates the ant, then flies out of the downed skull.

Each fly has about 200 eggs. It looks like introducing these flies to colonies can bring down the numbers by something like 80 to 90%. That sounds great, but: 1) there are so many colonies of these invaders; and 2) it takes a concerted effort to introduce the fly, since they're not native to North America either.

If you, too, can hear Seymour Skinner inn your head saying, "Well that's the beauty of the plan: in the winter the gorillas just freeze to death," as the end result of new waves of introduced species, fear not apparently. It is assured that the flies only attack fire ants, mainly because, the thinking goes, the egg-delivery method specifically evolved to target the species of fire ants that developed that buoyancy exoskeleton substance.

Lion Fish

Originally from the Indo-Pacific swath of ocean, the beautiful and venomous lion fish were dumped off the coast of the eastern United States a few years back, as well as somewhere in the Mediterranean. The problem here is that 1) they are wildly voracious, and devastate local fish populations; and 2) they reproduce quickly and face no predation in the Atlantic nor the Caribbean, where they have arrived.

They destroy reefs by eating all the fish that keep the algae on the coral in check, and once the algae-eating fish are gone, the corals tend to get choked out.

In Honduras, an effort to teach sharks to eat them has met with mixed results. On the other side of the planet, both sharks and groupers prey on lion fish, but in the Caribbean and the Atlantic, the sharks and groupers there never had them to prey on throughout theur evolutionary history, and while neither seem to be bothered by their poisonous dorsal spines, they also don't seem too interested in eating them.

The last line of predator defense against the lion fish's total take-over of the reefs of the Caribbean and Carolina's, is, eh, us. Humans.

There is a concerted effort to raise awareness of the destruction wrought by this invader by way of eating them. By popularizing the said-to-be-delicious meat of the lion fish, some order is hoped to be returned to devastated reef systems. It's open season on lion fish. 

I can't stress that enough: IF YOU GO DIVING OFF THE SOUTH EASTERN US, OR IN THE CARIBBEAN, KILL AS MANY OF THESE AS YOU SEE. It's as easy as that.

Postscript: Clearing Urchin Barrens

Similar in the sense that unchecked population growth is devastating, but different in the sense that they're not invasive, sea urchins can leave eerie landscapes where kelp forests used to thrive:

A before an after picture of urchin barrens and a kelp forest. The time it takes to go from the top picture to the bottom picture is not long: less than a month, actually.

I was reminded of this topic for a postscript because of the tact that some marine scientists took to help bring the kelp forest back in one place off the coast down here in LA. The normal urchin predators had been few and far between in the urban coastal scene south of Santa Barbara, so a couple of guys went out with hammers and smashed open every single urchin they could find. It was a massacre. 

Since they're not fast swimmers like lion fish, it was a little more straightforward. In five days there was a noticeable difference; within ten days holdfasts were supporting growing kelp; within three weeks it was a healthy, if young, kelp forest; and by day 28 the urchin barren was a distant memory.

It helps that kelp can grow two to three feet a day.

Sometimes it feels like a terrible ideology can be an invasive specie, and eradication seems both wildly necessary and practically impossible. At least with an invisible and indifferent invader, time is on our side, but the future seems like it will depend on how we deal with a terrible ideology.