Those who know me know that I watch a lot of Asian films: some very high quality ones, and some very cheap ones, the latter often featuring zombies and killer seafood. It turns out, though, that truth is again stranger than fiction.
Let’s start with the zombies – or should I say, ‘zombees‘? The US has been plagued with an outbreak of a parasitic fly (Apocephalus borealis) that lays eggs in foraging honeybees: these eggs hatch into larvae, which then eat the bee from the inside. By the time the bee is showing signs of infection (flying around at night, and generally behaving like a bee version of a B movie zombie), there’s little left of the bee but the shell, from which the fly larvae emerge as pupae, to mature into flies and start the cycle again.
An interesting aspect to this whole horror show is that it’s the honey bees that are the invading species, while the flies are natives. The bees were imported by settlers, while the flies, until recently, were only known to parasitise bumblebees and some wasps. Even given the short life span of the flies, a mere couple of hundred years have sufficed to allow the flies to adapt to new prey.
Then there’s the killer shrimp. Okay, it’s not a killer of humans, but it’s a pretty effective killer of other shelled sea creatures, due to a punch that could beat any martial artist clear across the room.
I’ve been fascinated by the peacock mantis shrimp (Odontodactylus scyllarus) ever since I saw Rosemary Mosco’s nature comic Animals With Misleading Names. It’s one of the group known as ‘smashers’ (yes, that’s the technical term: the other group of the suborder Unipeltata are known as ‘spearers’), which refers to their method of attacking prey. But it’s not just brute force that makes them special, it’s the speed with which they can apply this force. These little suckers can punch with a speed of 23 metres per second (that’s about 82 km/hr, or about 51 miles per hour) from a standing start, accelerating at about 102,000 (yes, all those zeros) metres per second squared: about the acceleration of a speeding bullet.
They achieve this using their own version of a weapon that’s been used throughout recent human history: the catapult, or onager. The smashing arm is structured something like an anglepoise lamp, with a muscle spring at the angle. They hold back this smashing arm with a hook, and slowly (relatively speaking) wind back this spring: when they release the hook, the arm hits the prey like Maxwell’s silver hammer.
But the blow itself doesn’t do all the damage. Because of the high speed of the impact, a small bubble of vaporised water forms and then bursts against the shell of the victim, often with a tiny flash of light. This is a process known as cavitation, which is strong enough to pit holes in the (stainless steel) propellers of water turbines or powerboats, so a small crab doesn’t have much chance.
Here’s high speed footage (at 5,000 frames per second) of the peacock mantis shrimp striking: high speed film, because it’s the only way you’ll ever be able to see it happen. If you’re able to see the moment of impact, you might catch the little white bubble that appears and implodes: this is the cavitation bubble that helps to make the punch so devastating.
Then there’s their eyes: mantis shrimps have the ability to see far into the infrared and ultraviolet, to see polarised light, both linear and circular, and to see in 3D, making their visual world far richer than ours. This means that when you put on 3D glasses to watch a movie, you’re turning yourself into a mantis shrimp, although without the smashing claws.
It’s worth having a read of this Wikipedia article about mantis shrimps, because these animals have more fascinating characteristics than I can fit in a short blog post, and I’m in danger of turning into E. L. Wisty (a Peter Cook character), and boring people with a lot of interesting facts.
[Featured image: Peacock mantis shrimp. Image by silke baron, licensed under Creative Commons 2.0.]