“A Perfect Invader” Is Taking Over The Ocean – 185,000 Eggs At A Time

Enter: the European green crab, Carcinus maenas. They are a staple feature across parts of the Atlantic Ocean and Baltic Sea, but have since spread from their native home to invade large swathes of the planet. Some have labeled them “supervillains” for their capacity to spread, and in Canada, they’re trying to solve the problem by turning them into biodegradable plastic.

European green crabs: a perfect invader

They have a few traits that make them, as conservation biologist Joe Roman put it to The New York Times, “a perfect invader”. They eat everything, they can tolerate all kinds of water temperatures and salinity, and a single crab can produce 185,000 eggs per brood.

Yes, green crabs have many tricks up their claws, but perhaps their ultimate survival superpower is their incredibly nomadic larvae. When that female unleashes her 185,000 eggs on the world, they hatch and release larvae that have the potential to drift for around two months. Alone, a small speck of crustacean can cover only so much ground – but factor in we humans and our ships, and that 60 days becomes a much bigger window of opportunity.

Crabs + ships = world domination

Modern-day cargo vessels pick up and discharge water every time they make port, swallowing up and churning out green crab larvae that Roman said can stretch into the tens of millions. There aren’t many other species that would survive so long under these conditions, but in this way, green crabs have been hitching a free ride and scuttling out into non-native environments to eat whatever happens to be around.

The effect of this invasive crab invasion is seen across all kinds of life, threatening plants, contributing to erosion, and worsening climate change by degrading habitats. They have few natural predators – other than otters, which have done a fine job of chomping away at green crab populations in California – but could we throw a new predator into the fray? How about… ourselves?

The invasivore diet

Roman first proffered the “invasivore diet” in a 2004 article – and as a solution to invasive species, it’s more relevant now than ever. At a time when the harmful practice of octopus farming is becoming a burgeoning industry that addresses the dietary preferences of only a wealthy few, wouldn’t we be better off if we instead turned our focus to finding delicious ways to enjoy the animal protein we have far too much of?

In many cases, “invasions” like the green crab are the result of human activity. We have introduced species to all sorts of environments they weren’t supposed to ever access – sometimes on purpose, like possums and the establishment of a fur trade in New Zealand; and other times by accident, like our hitchhiking green crabs.

These invasive species are only doing what they do best, but if the natural order is to be preserved, it falls to humans to undo the damage done by the introductions we facilitated. Massive projects have eradicated animals from places they ought not to be, like rats on South Georgia Island, but in some places, the solution could also address global food demand.

Crabs aren’t alone as a species of interest to the invasivore diet. The invasive European weed garlic mustard has become a peppery addition to salad dressings, and sushi chefs have turned their craft to incorporate the highly invasive lionfish that’s thought to have spread across the world due to people dumping aquarium pets in the ocean.

Roman’s website Eat The Invaders hopes to continue to inspire this culinarily creative fix to invasive species, with a memorable mantra to boot: “Fighting invasive species, one bite at a time.”