Not every predator goes for a quick and simple kill. Parasites slowly steal sustenance from other organisms - and some take an approach fit for a horror movie. Let's take a look at...
1. Parasitic BarnaclesWhen you think of a barnacle, you would probably picture a shelled creature affixed to a rock or bit of wood. The European shore crab Carcinus maenas might have a different perspective since Sacculina carcini repurpose them as a combined food bank and nursery.
When a female larvae lands on a crab, it burrows into the unfortunate crustacean. Small rootlets allow the larvae to steal nutrients as it hijacks the crab. The parasite then matures and grows an egg sac under the belly of the crab, which male parasites swim into and fertilise.
The barnacle doesn't just steal nutrients and a lift; it sterilizes the host and even tricks the hapless crabs into caring for its eggs. Not all hosts are female, but the barnacle has another ability - it can change the body of a male host, widening the abdomen and giving them female characteristics. It also affects the endocrine system of the male crabs, giving them nurturing instincts!
After maturing, the female parasite will break back out of the host, leaving her anterior (head and upper body) section outside of the victim whilst remaining lodged in the bee. The rarer male parasites will leave the host entirely, flying off in search of an exposed female with which to mate. The female never leaves the host, and simply produces larvae that wait for a new victim. The host bees seem able to function fairly normally, but with stunted development and reduced sexual characteristics.
The protozoan Toxoplasma gondii makes a home in the bowels of a cat, producing oocysts (egg-like structures) that are expelled from the animal and must make their way into a new feline. They do this by infecting an intermediate host (such as a rat) that consumes something contaminated by the oocysts. Once inside the intermediate host, the protozoan replicates and walls itself inside tough cysts for protection until the rat gets eaten.
The protozoan isn't content to wait for the rat to make a mistake. While not directly harmful, the microorganism interferes with the neurotransmitters found rat brains, removing any fear of cats and even attracting them to the scent of feline urine. This tends to end with a dead rat, a satisfied cat and a new home for the protozoan.
4. Mind-Bending CordycepsImagine you are a foraging ant - you've found some food and brought it back to the colony, though you did see a few dead ants on your trip. A week later you start feeling twitchy, eventually losing your grip on a branch. You climb up the stem of a shrub and anchor yourself beneath a leaf with a bite, only to find that you can't let go. Shortly afterwards, you are devoured by the fungus infesting your body, and a small mushroom emerges from your back to spread spores across the forest floor.
Found throughout the world, the Cordyceps and Ophiocordyceps families of fungus specialize in parasitizing insects and other arthropods, growing mycelium through the body of the unfortunate host before bursting out of the head or back in a fruiting body. Some varieties, such as Ophiocordyceps unilateralis, are capable of manipulating the behavior of their hosts, getting them to die in locations that will ensure a good dispersal of spores. The fungus is so dangerous that some ants have started to adapt, avoiding the forest floor where the spores are thickest, cleaning each other's carapaces and throwing infected ants away from the colony.
Cordyceps and Ophiocordyceps fungi are used in folk medicine. You have to wonder about the wisdom of ingesting a parasitic fungus with limited mind-control powers...
The parasitic wasp Dinocampus coccinellae seeks out an adult female ladybird and implants an egg in the host's vulnerable underbelly. The wasp larva feasts on the ladybird's body fat for about a month before paralyzing the beetle (scientists think this is due to an RNA virus also injected by the wasp - it seems like nature is a big fan of Resident Evil) and tunneling out, forming a cocoon underneath the host.
The beetle's ordeal isn't over yet - the now "zombified" ladybird is forced to act as an unwilling decoy, with the bright coloring and sporadic twitching deterring any of the usual predators that would try to eat the cocooned grub. Despite the damage dealt by the parasite, around a quarter of the unfortunate ladybirds survive the process and recover.
The round galls found on oak trees are caused by gall wasps, who inject eggs and chemicals that cause oaks to grow around the invading object. The larvae consume the insides of the gall and then burrow free. The larvae may also be parasitized by other wasps, who plunge their ovipositor into the gall and inject eggs into the helpless grub. Perhaps the most dramatic example is the crypt-keeper wasp Euderus set, found in the south-east of the USA.
The crypt-keeper seeks out the galls of another wasp (Bassettia pallida) and injects their own egg. The fresh crypt-keeper burrows into and controls the pallida larvae, forcing it to burrow through the gall and providing an escape for the physically weaker crypt-keeper. The hole is too small for the pallida to get through, meaning it gets stuck and held in place while the crypt-keeper eats up through the body. It exits by bursting out of the head, using the grub like an organic escape tunnel!
- Parasitic Barnacles
- Bee Backpacks
- Rats, Cats and Protozoans
- Mind-Bending Cordyceps
- Ladybird-Zombifying Wasps
- Crypt-Keepers and Oak Galls
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| Both rats and cats are part of the Toxoplasma gondii life cycle... () |
1. Parasitic BarnaclesWhen you think of a barnacle, you would probably picture a shelled creature affixed to a rock or bit of wood. The European shore crab Carcinus maenas might have a different perspective since Sacculina carcini repurpose them as a combined food bank and nursery.
When a female larvae lands on a crab, it burrows into the unfortunate crustacean. Small rootlets allow the larvae to steal nutrients as it hijacks the crab. The parasite then matures and grows an egg sac under the belly of the crab, which male parasites swim into and fertilise.
The barnacle doesn't just steal nutrients and a lift; it sterilizes the host and even tricks the hapless crabs into caring for its eggs. Not all hosts are female, but the barnacle has another ability - it can change the body of a male host, widening the abdomen and giving them female characteristics. It also affects the endocrine system of the male crabs, giving them nurturing instincts!
2. Bee Backpacks
Like a miniature chimera, some female mining bees sprout a second head from their back - a tiny parasitic insect known as Stylops melittae. The larvae wait on flowers for a bee, grabbing on and hitching a ride back to the nest. The larvae then find a vulnerable bee and burrow inside their exoskeleton, helping themselves to nutrients filtered from the haemolymph (insect blood) of their host.After maturing, the female parasite will break back out of the host, leaving her anterior (head and upper body) section outside of the victim whilst remaining lodged in the bee. The rarer male parasites will leave the host entirely, flying off in search of an exposed female with which to mate. The female never leaves the host, and simply produces larvae that wait for a new victim. The host bees seem able to function fairly normally, but with stunted development and reduced sexual characteristics.
3. Rats, Cats and Protozoans
The humble rat is justifiably afraid of cats. They typically seek to avoid all contact, and the mere scent of cat urine is enough for them to scurry in the other direction... usually.The protozoan Toxoplasma gondii makes a home in the bowels of a cat, producing oocysts (egg-like structures) that are expelled from the animal and must make their way into a new feline. They do this by infecting an intermediate host (such as a rat) that consumes something contaminated by the oocysts. Once inside the intermediate host, the protozoan replicates and walls itself inside tough cysts for protection until the rat gets eaten.
The protozoan isn't content to wait for the rat to make a mistake. While not directly harmful, the microorganism interferes with the neurotransmitters found rat brains, removing any fear of cats and even attracting them to the scent of feline urine. This tends to end with a dead rat, a satisfied cat and a new home for the protozoan.
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| Cordyceps fungi can twist the brains of their hosts before killing them... (Docujeju) |
4. Mind-Bending CordycepsImagine you are a foraging ant - you've found some food and brought it back to the colony, though you did see a few dead ants on your trip. A week later you start feeling twitchy, eventually losing your grip on a branch. You climb up the stem of a shrub and anchor yourself beneath a leaf with a bite, only to find that you can't let go. Shortly afterwards, you are devoured by the fungus infesting your body, and a small mushroom emerges from your back to spread spores across the forest floor.
Found throughout the world, the Cordyceps and Ophiocordyceps families of fungus specialize in parasitizing insects and other arthropods, growing mycelium through the body of the unfortunate host before bursting out of the head or back in a fruiting body. Some varieties, such as Ophiocordyceps unilateralis, are capable of manipulating the behavior of their hosts, getting them to die in locations that will ensure a good dispersal of spores. The fungus is so dangerous that some ants have started to adapt, avoiding the forest floor where the spores are thickest, cleaning each other's carapaces and throwing infected ants away from the colony.
Cordyceps and Ophiocordyceps fungi are used in folk medicine. You have to wonder about the wisdom of ingesting a parasitic fungus with limited mind-control powers...
5. Ladybird-Zombifying Wasps
Ladybirds (or ladybugs) scuttle around eating aphids and pleasing gardeners and kids alike with a bright red shell. It turns out they have another "admirer" though - and it's one that would fit in a body-horror movie.The parasitic wasp Dinocampus coccinellae seeks out an adult female ladybird and implants an egg in the host's vulnerable underbelly. The wasp larva feasts on the ladybird's body fat for about a month before paralyzing the beetle (scientists think this is due to an RNA virus also injected by the wasp - it seems like nature is a big fan of Resident Evil) and tunneling out, forming a cocoon underneath the host.
The beetle's ordeal isn't over yet - the now "zombified" ladybird is forced to act as an unwilling decoy, with the bright coloring and sporadic twitching deterring any of the usual predators that would try to eat the cocooned grub. Despite the damage dealt by the parasite, around a quarter of the unfortunate ladybirds survive the process and recover.
6. Crypt-Keepers and Oak Galls
A locked room mystery with corpses stuffed inside each other like a grisly Russian doll, no obvious way for an intruder to enter and no signs of a struggle. Doesn't sound like an oak gall, does it?The round galls found on oak trees are caused by gall wasps, who inject eggs and chemicals that cause oaks to grow around the invading object. The larvae consume the insides of the gall and then burrow free. The larvae may also be parasitized by other wasps, who plunge their ovipositor into the gall and inject eggs into the helpless grub. Perhaps the most dramatic example is the crypt-keeper wasp Euderus set, found in the south-east of the USA.
The crypt-keeper seeks out the galls of another wasp (Bassettia pallida) and injects their own egg. The fresh crypt-keeper burrows into and controls the pallida larvae, forcing it to burrow through the gall and providing an escape for the physically weaker crypt-keeper. The hole is too small for the pallida to get through, meaning it gets stuck and held in place while the crypt-keeper eats up through the body. It exits by bursting out of the head, using the grub like an organic escape tunnel!
Thanks for reading - for more curious creatures, try...