We may think of parasites being small and microscopic, but they’re not all like that… Meet the world’s biggest parasites
The word parasite alone can make your skin crawl. Parasites can be either viruses or organisms, and can be anything from inconvenient pests that don’t normally kill to mind-controlling puppet masters with (often disgusting) life strategies that have evolved to benefit themselves at the cost of others.
What is parasitism?
Parasitism is a relationship in which one partner exploits the resources of the other. Discover the world’s most deadliest parasites
What’s the biggest parasite?
A good place to look for a big parasite is in a big host. The whale tapeworms Polygonoporus spp., for example, can reach 40m in length – longer even than a blue whale, which grows to 33m.
However, in comparison with their hosts, horsehair worms are longer still. The larvae develop in the bodies of grasshoppers, crickets and other insects; the adults, once matured, must disperse into freshwater to breed.
At this stage the worm may manipulate its host, compelling it to jump into water, where the parasite – usually 30-40cm long, though it can grow to over 2m – makes a spectacular exit through the insect’s rear end.
What worms boast in length, however, they tend to lack in volume. Sheer bulk can be found among the brood parasites. A pair of reed warblers, for example, may raise a cuckoo chick that could be four times their own combined weight.
But trumping all of these are the honey fungus Armillaria spp. These form subterranean networks of woody fibres that tap into tree roots and kill them. on their way. In 1992, a specimen of A.solidipes in Washington state, USA, was found to cover 900 ha.
For an idea of its mass, a mere 15 ha specimen of a related species weighed 100 tonnes, so the Washington example may weigh many hundreds of tonnes. The world’s biggest parasite is, therefore, also a contender for the title of the world’s biggest organism.
Discover some more weird, wonderful – and frankly sometimes disgusting -parasites
- Meet the green banded broodsac, a deadly – and frankly – weird zombie parasite that turns a snail’s eyestalks into colourful, pulsating glowsticks
- How a flatworm parasite makes frogs create an extra leg or two
- Ugh there’s a tongue-eating parasite? Afraid so, and it grows as big as a cockroach. Meet Cymothoa exigua
- It’s a slimy, prehistoric parasite with the mouth of an alien. And two fearless photographers are obsessed with finding it
- Cordyceps and Ophicordyceps: the zombie parasitic fungi made famous by The Last Of Us