What is the death trigger?

[Domanating]

I've been pondering on this because of what happened here recently. 3 days ago I had 3 live M.Religiosa (females, obviously). One of them was pretty beaten up. She aged very quickly. Her wings got brown stains. Her antennae were rotting and the legs breaking apart very early.

The two others by comparison were doing incredibly well. The were always thin and elegant, laid several small ooths once in a while. They had an abnormally healthy hunger and thirst for their age. For my astonishment, they both still had their legs intact and working. They were incredibly active for their age.

And yet, 3 days ago the healthiest looking one dies in less than 2 hours after the start of the death symptoms. Two days later the other apparently healthy one dies in 4 hours. The Mantis with rotting antennae that I was expecting to die in late November, surpassed all others in longevity and is still going strong (I hope). That surprised me more than it should.

The 2nd mantis death was horribly gruesome and it's something I've never seen before. No such thing as the typical spasms. She bled to death.

It started when I went to check on her and she had a weird vivid green thing on the back of her neck. It seemed like dry blood and it was easily removed with a pair of tweezers. I saw no apparent wound on her neck but the weird contractions of her abdomen confirmed that the death switch was on. I then decided to keep a close eye on her.

I wasn't prepared for the blood shower that happened afterwards. Now I'm not sure if she bitten herself or not. i did not see any clear bite wounds but there was blood pouring from her fore arm articulations. Then blood started oozing behind her head and behind her mouth parts. It was a very vivid green liquid and I couldn't see any indications of wounds!

I'm not a guy that gets easily scared but that creeped the heck out of me... Apart from the blood part her death was very quiet compared to most that suffer massive spasms.

I drifted a bit too much from my point I think. It's like there's a an on/off switch that nearly instantly tells the mantis to die. Some deaths do have very obvious reasons, like gangrene, infections causing a slow, deteriorating death. But in these ocasions, those answers don't fit very well

 

[Ranitomeya]

With most invertebrates that have a final molt, their life span is generally limited by how long their exoskeleton and joints can stay intact as well as how well their body is capable of sealing off any damage done to their exoskeleton and joints. The insect exoskeleton is a layer of non-living proteins that break down over time and unless they continue to molt, so you can expect them to eventually start falling apart. Longer-lived insects that have a final molt tend to have much sturdier exoskeletons and joints, but they too begin losing limbs and appendages in the end.

While it's possible that something switches on or off, it's also likely that their exoskeletons begin to break down as they begin to lose the ability to seal off and repair damage with age. Losing the structural integrity of their exoskeleton and succumbing to disease is something to be expected as an invertebrate ages and their ability to fight disease and repair damage that would allow disease to enter their system diminishes.

 

[Domanating]

That does apply to visible health deterioration such as loss of appetite, vomiting, gangrene, the black death, infections and others over time. But I don't think any of these issues can be so catastrophic that progress from completely healthy and reacting normally to dead in a couple of hours.

 

[Ranitomeya]

Mantids are relatively soft creatures and if fed well, there's quite a bit of internal pressure--they'd essentially be like water balloons with hardened plates. If there was a sudden and catastrophic loss of integrity of the joints, you can expect them to suddenly start bleeding from the joints like you described. You may not have seen a wound, but that does not mean there weren't tiny fissures or cracks in the membranes of the joints. I'd imagine that all the stretching and shrinking of the joints over the course of their adult life coupled with the gradual loss of flexibility of the membranes due to damage of the proteins can eventually cause this.

 

[Domanating]

Kind of a big coincidence to have a lot of joints failing at almost the same time...

I filmed part of the bleeding if you want to take a look. I sometimes put a camera rolling for hours, filming their deaths to get a better understanding of the phases they go through. Unfortunately only the start of the... event if you will, was filmed. Because the camera was low on battery and I didn't notice it turning off, and that was a real bummer.

 

[Ranitomeya]

It isn't too unbelievable that joints composed of the same material, produced at the same time, and that have undergone the same stresses over the same course of time would fail around the same time.
The "death trigger" may very well just be the body shutting down and failing to repair itself.

 

[DETHCHEEZ]

Wow...

I've been been raising mantids on & off for a good 12 years

&

Can say I've never had one rot or just fall apart

Or

Have seen anything like what you described

&

Hope I never do

Any chance that it could have been some sort of parasite

 

[[email protected]]

That is awful! I'm sorry that happened.

 

[Domanating]

Wow...

I've been been raising mantids on & off for a good 12 years

&

Can say I've never had one rot or just fall apart

Or

Have seen anything like what you described

&

Hope I never do

Any chance that it could have been some sort of parasite

You never had one mantis falling apart? That's hardly believable, m8. It's way too common for a mantis or any kind of old insect to to have darken legs that stiffen and break off. Maybe "falling apart" might be an exaggerated term for it but for an animal that loses parts of their legs and antennae I think it's accurate .

About the blood part that's a first to me aswell. I don't think it was parasite. First because there is no parasite here that could harm a mantis that I know of. If there is, I never kept one affected by any. The only typical insect parasites found here that I know of are parasitic wasps and these usually prey on aphids and caterpillars.

Mantids with parasites will show clear signs that something's wrong. Their behaviour usually changes. Mine seemed perfectly normal.

Ranitomeya's theory, although a bit unprobable, makes sense.

However I came up with another propable cause for the "death switch": Organ rupture. It's not an uncommon ocurrence to any animal and it's more likely at old age.

A rupture in the digestive tract can poison the entire body of the mantis quickly and kill it in a reasonably short period of time.