A Corpse Carrying Insect - Animal of the Week

Welcome to a new episode of Animal of the Week. Last animal of the week was the Pompei worm for our Worm Week special, but today we're moving on from worms to insects with this week's animal, Acanthaspis petax. This insect is a species of assassin bug, a huge family of over 7000 species called Rhodovidae. Acanthaspis petax is of a particular interest within this huge family due to its bizarre behaviour of corpse camouflage, which I will explain in detail in the adaptation section. Many other species of assassin bug also partake in this behaviour, however because not every single one of the 7000 possesses this behaviour, I thought it best not to generalise and so picked a specific species that displays this amazing behaviour the best. Acanthaspis petax require savannah habitat and so inhabit the region of East Africa surrounding Lake Victoria in the countries of Uganda, Kenya and Tanzania. They have also reportedly been seen in Western Asia, so the Middle East region, as some areas like the Levant do have environments close to that of the savannah. However reports of these specific assassin bugs in these other regions can't be entirely relied upon as it would be rather strange to have two separate populations so far apart from each other. In my opinion it's more likely that the reported sightings of these bugs in West Asia could be one of the other 7000 species of assassin bug that are very similar to them, and remember many of those 7000 also use corpse camouflage like acanthaspis petax. Another reason I'm sceptical is because one of the places that these insects like to live is the abandoned mounds of fungus growing termites. Now fungus growing termites live in Africa and they do also live in Asia, however primarily in Southern Asian countries like India and not in West Asia. Again this is perhaps conjecture but the relative unreliability of the sightings coupled with the vast distance between the two populations and the lack of one of the main dwellings of the insect in West Asia makes me personally sceptical. However I could very well be wrong as I do not live in West Asia and have no first-hand evidence. What lends credence to them actually living in West Asia as well is that there are more concrete sightings and studies of them in Malaysia which shows that there can easily be two separate populations vast distances apart, so in the end who knows. If you're wondering what these insects eat, well just take a look at their back and you can tell. Now it must be said that only the juveniles known as nymphs take part in this corpse camouflage but as the diet of the insect does not change much over their lifetime, what's on the back of the nymphs is also what the adults eat. Primarily they eat ants, however we'll dabble in flies, termites, grasshoppers and beetles. These insects are of course assassin bugs and there is a very real reason for that name because they are primarily ambush hunters and are very deadly at it. They possess a long and very sharp proboscis. The proboscis acts like a needle and injects the prey with digestive enzymes and paralyzing saliva. The prey then dissolves inside of its own exoskeleton and the liquidy remains are sucked right out. The precision and effectiveness of this method of hunting really makes you see why they are called assassin bugs. The way they breed is typical for many insects. They have the ability to stridulate which can be used for defensive purposes however it is also known to be used to attract mates in many insect species so perhaps it is not unreasonable to guess they might use it for the same thing. It would certainly come in handy for these insects as they are notoriously slow, individualistic and hard to find. The male and females need to copulate to reproduce and once finished the females will lay eggs. The eggs hatch and will develop into the nymph stage which is the stage at which they use corpse camouflage as they are vulnerable to predators and also inexperienced hunters so they require plenty of camo for ambush hunting. We know that the corpses are definitely used for camouflage but we are still unsure how it fully works because you would think putting a load of dead bodies on your back would make you more visible. There are currently many different theories. One is that they use the ants in the same way that naval ships used to use dazzle paint. The ants simply disrupt the shape of the insect in order to confuse the perspective and outline of it, putting off any predators and confusing any prey as they can't quite make out what they're looking at. Another prominent theory is that they are trying to make themselves look like a swarm of ants which can ward off predators. Evidence in support of this theory is the fact that despite preying on many different things they usually only use the ants for camouflage. However they also only use things that are not animals to add to the look such as leaves and sand so maybe this isn't as strong evidence as first thought and an ambush predator trying to seem like a swarm of obvious and dangerous ants seems counterintuitive. However this is thinking from a predatory standpoint and if we consider camouflage to be primarily for protection it makes more sense. This is because their main predators saltacid spiders don't prey upon ants so it could perhaps be a very targeted camouflage to put off their main predator. The final theory is that it is not a visual camouflage but an olfactory, masking the smell of the insect. The sand they use could be an attempt to dampen their smell. The way in which they actually attach stuff to themselves is almost like a spider's web. They have hairs on their back that secrete a sticky thread that allows stuff to stick to them. Clearly many things threaten them due to their extensive camouflage however adults are a lot safer despite not using any. This is because adults are nocturnal unlike the nymphs and so use the cover of night as protection. They have a lot of behavioral adaptations to threats as well such as playing dead and the nymphs are even able to jettison their luggage and escape leaving the ball of dead ants as a distraction. Human wise we don't really know what we are doing to them as there is a lack of overall population study. Hopefully they will be okay however they already like to live in dry hot conditions and when these areas get even drier and hotter they may not survive. Thank you for watching this video I really hope you enjoyed it and learned something new. 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