The conqueror’s biotic army

still from Oil Blue, Directed by Elli Rintala. Finland.
still from Oil Blue, Directed by Elli Rintala. Finland.
The alien ctenophore Mnemiopsis leidyi (Comb Jelly)
Mnemiopsis leidyi (Comb Jelly)

Oil tanker ballast water has carried the beautiful invasive comb jelly to a myriad of seas, where is successfully settled. There is an argument that conquering peoples (or ideologies) are accompanied by a successful invasion of accompanying non-human animal allies, who help settle the land in new ways that upended the unprepared native inhabitants. Of course, this often backfires (as do conquerors).

see the ISSG global invasive species database

see also the book, “Ecological Imperialism: The Biological Expansion of Europe” Alfred W Crosby

Chinese Mitten Crabs

Chinese mitten crab. Image courtesy of the New Zealand Ministry of Fisheries.
Chinese mitten crab. Image courtesy of the New Zealand Ministry of Fisheries.

From the Non-Native Species site:

The Chinese mitten crab is a native of East Asia, introduced into Europe in the 1930s. It is thought to have been transported to Britain in ships’ ballast water (juvenile crabs and larvae) or perhaps by adult crabs clinging to ships’ hulls. The species has six larval development stages and it is understood that for complete development the larvae need to migrate to the open sea. Dispersion of the species is assisted by the pelagic larvae and mobile adults. Adults live in freshwater migrating to river estuaries and coastal regions to breed.

From the site, Marine Aliens:

The Chinese mitten crab has increased markedly in the last 10 years in the UK. This invasive species can cause serious structural degradation and pose a significant threat to native communities in estuarine systems. As a consequence, it has been placed on the IUCN 100 of the World’s worst invasive alien species list. The largest UK population of mitten crabs is located in the Thames region, including the Medway and Blackwater estuaries. This species has also been reported from the Humber and Tyne. Click here for video footage of the Chinese mitten crab.

Chinese Mitten Crabs(大闸蟹).

A Chinese delicacy, especially when their gonads are enlarged, “They are considered as the best yummies of the .” It appears they live in freshwater but migrate to the sea in the fall to mate – a time in which the femailes are “very plump.” (

Spicy Salt Hairy Crabs
Spicy Salt Hairy Crabs

If you can’t beat them, eat them.

from The Guardian, March 2009:

“Eating the enemy – Alien species are being put on the menu in what campaigners say is the perfect green solution to save the UK’s native animals”

What can be done about invasive alien species? Governments and conservationists try to eradicate them, sometimes at enormous expense, but one group of people has another idea: just eat them.

Ben Carter, a north Yorkshire zoologist working in fisheries management, is making a very good living trapping the environmentally-damaging American crayfish, selling up to 20,000 a week as a gourmet delicacy to some of the country’s top chefs…

The American crayfish (Pacifastacus leniusculus) is currently a big problem in the south of England, but has reached as far north as Yorkshire and is threatening the protected native white-clawed crayfish (Austropotamobius pallipes)…

Britain is full of other non-native species, and most of them are edible. The Pacific (Crassostrea gigas) and New Zealand flat (Tiostrea lutaria) oysters, introduced here during the last century, are both now thriving along sections of the English, Irish and Welsh coasts.

Feral populations

The tiny Muntjac deer (Muntiacus reevesi), first introduced here from China to amuse the Duke of Bedford at Woburn Park in the early 20th century, has led to feral populations becoming widespread across England and Wales following escapes and deliberate release. Aficionados swear it makes lovely venison.

The ruddy duck (Oxyura jamaicensis) – very popular roasted in America – was introduced into British wildfowl collections in the 1950s. It is now widely distributed in the UK, and also threatens the survival of Spain’s white-headed duck (Oxyura leucocephala)…

Elsewhere, Britain’s waterways are threatened by an invasion of the Chinese mitten crab (Eriocheir sinensis), which could be the next environmental nuisance to take off as food…

Britain’s 5 million grey squirrels (Sciurus carolinensis) have become all but friendless in the UK for endangering the red squirrel, and … created a demand for squirrel meat – the ultimate organic free-range game.

Alongside the grey squirrel, wild boar (Sus scrofa) may not seem such a problem – or opportunity – but feral breeding populations have recently re-established themselves following illegal release or escapes of farmed stock.

the tourist as an invasive species

Photo: Ancia Ontour
German Tourists. Photo: Ancia Ontour

Here are some common traits belonging to invasive species . A tourist fulfills most of the criteria on the checklist.

  • The ability to reproduce both asexually as well as sexually (garbage and cultural leavings as a byproduct)
  • Fast growth
  • Rapid reproduction (not restricted to babies)
  • High dispersal ability (planes trains tour-buses cruise ships)
  • Phenotypic plasticity (the ability to alter one’s growth form to suit current conditions) (dress native, get all the right travel gear, dip in and out of cultures)
Tourists in Alaska
Tourists in Alaska
  • Tolerance of a wide range of environmental conditions (generalist) (again, specialized gear)
  • Ability to live off of a wide range of food types (generalist) (when in Rome…)
  • Association with humans (anthro-fetishism and the McDonald’s phenomenon)
  • Other successful invasions (war and peace)

(from wikipedia)

Tourists buying postcards at Yellowstone National Park, 1946. Photo - Alfred Eisenstaedt
Tourists buying postcards at Yellowstone National Park, 1946. Photo - Alfred Eisenstaedt

GB Non-Native species list

From the GB Non-Native Species Secretariat:

The term ‘non-native species’ is used throughout this website and is the equivalent of ‘alien’species’ as used by the Convention on Biological Diversity (CBD). Invasive non-native species (the equivalent of invasive alien species or IAS) are broadly defined as species whose introduction and/or spread threaten biological diversity. Non-native species covered by this website include all fauna and flora with the exception of genetically modified organisms (GMOs), bacteria and viruses. Non-native species also refers to species native to Great Britain but outside of their normal range.

Here’s a list of fact files available on the GB NNS site:

Species include a plethora of water weeds, algaes, mollusks, (mostly transported in  water ballast), and  escapees from the agribusiness, pet and fur trades.