Epiperipatus barbadensis (Barbados Brown Velvet Worm) Care Guide

As is true for all my care guides, this is not intended to be taken as the only way to keep these fascinating animals.
This has been one of the most requested guides for me to write. After years of working with these animals and having nearly losing my entire colony twice, I am confident enough to share what I've learned and has helped me succeed. 
Epiperipatus barbadensis - Barbados Brown Velvet Worm - is a medium sized member of the phylum Onychophora. Onycophora may look like worms with nubs, but they are actually considered part of the (debated) clade Panarthropoda. If you're into taxonomy at all, you would know that in order to classify something as an Arthropod it must have 3 specific characteristics. The requirements are that the animal molts/sheds its skin as it grows, it must have jointed legs, and lastly it must have a segmented body. 
If you take a quick look at a velvet worm, you wouldn't think it has any need to shed. You'd be wrong. Velvet worms do in fact shed as they grow. They may not have a hard exoskeleton, but their velvet looking appearence is due to their skin being comprised of chitin (like exoskeletons), extremely tiny scales, and little papillae (bumps like those on your tongue). 
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"Well it doesn't have a segmented body...or does it?"

Velvet worms are in fact segmented! It isn't as obvious as seeing the body segments of an ant or spider since their segments are visible from just looking at them. Their body is made of rings with pair legs that come off of them, and they also have a 3 segmented head comprised of the antenna, mandibles, and oral papillae.

"Ok, but they definitely don't have any joints in their legs." 

You're correct! Their chubby stubby legs - called lobopods - are fluid filled nubs with 2 tiny claws on the end. They gain a new pair of legs every time they shed and grow. The lack of joints in their legs is why they are classified as Panarthropods and not Arthropods. 
Something I get asked quite often about them is if they are hard to care for. Sad to say these amazing creatures seem to prove difficult even for some experienced keepers. I tend to keep my colony around 75°F-82°F (~24°C-~27.5°C) with humidity between 80-90%. I have experimented with humidity as low as 65%, but the lower the humidity is, the more they will hide. The easiest way I have found to maintain such a high level of humidity is to setup your animals in a bioactive vivarium. Now when people hear bioactive nowadays, most seem to think that just involves having live plants, springtails, and isopods in the enclosure. While those are some components that are included into a bioactive enclosure, what really makes it bioactive is a healthy establishment of fungi and bacteria. This is something the majority of keepers never even consider. Think of setting up a fish tank. You add your substrate, plants/coral/live rock, fill with water, add bacteria, and let it cycle for a couple weeks until the tank has established enough beneficial bacteria to keep the water clean. Ideally you want to do the same for your velvet worms. 
The way I set mine up was to first put a couple inches of vermiculite on the bottom of the enclosure and covered it with a screen to create a drainage layer. Even though these animals enjoy high humidity, they are not designed to be sitting on super damp substrate. 
Next comes substrate. I use a mixture of coco coir, soil, and some live moss. There is also a layer of leaf litter which acts as both hiding spots and it helps create areas of different micro climates within the vivarium. As far as substrate depth, as deep as your plants will require is fine. Adult E. barbadensis do not burrow, but I have observed the babies digging down a small way into the substrate. Live plants are great in a vivarium because they provide oxygen, can aide in humidity, and provide hiding spots. These animals are photophobic (hide when they see light), so the more shady spots for them to retreat to, the more comfortable they will feel. If your vivarium is setup to have enough shade, you may even get to see them walking around during the day.
Alright onto the fun part - feeding time.
Feeding these animals is pretty easy. Most live inverts seem to be fair game (within proportion to their size). Even prekilled invertebrates are readily accepted. My favorite prekilled feeder to use are dubia (Blaptica dubia) roaches. I kill the roach and cut it in half. Even though they cant chew through the tough exoskeleton, they readily eat the innards. They will even feed communally. If you're very lucky you will get the opportunity to watch them do what made them so famous - shoot goo! 
Onycophora have specialized papillae on their head just in front of the first pair of legs. These papillae are each connected to their own slime glands which they contract in order to spray their slime not only as a defense, but to glue their prey in place. The slime has a similar reaction to moisture the same way cyanoacrylate (CA glue/super glue)  does, it hardens to make it even more difficult to escape. After glueing down their meal, they use mandibles equipped with sharp teeth to slice open the prey. They pump their saliva into the wound as they chew, the enzymes digesting the innards quickly so the velvet worm can slurp it up. Any remaining exoskeleton should be removed to prevent mold from growing.
As long as everything is setup properly and the animals are old enough, breeding takes no effort at all. After mating, females will start to grow embryos in succession in the uterus. Imagine looking at a conveyor belt with boxes on it. As the boxes move down the line something gets added to each until they get to the end. The first box down the line is full and ready to be shipped. The next box is almost there but not quite full. The box after that has less in it and needs more time to fill, and on and on it goes. This is how the embryos form, with the female birthing 1 live baby at a time. Babies can be observed staying near their mother until they get a certain size. Epiperipatus barbadensis hasn't been studied by scientists all that much, but going off other peripatopsids, you can expect the female to give birth to anywhere from 6-20+ babies in a year.
Earlier I mentioned setting them up in a vivarium and usually that means add isopods and springtails. There are 2 issues with that. Velvet worms are very soft bodied and not all that fast. They can only shoot so much slime before needing to recover also, so hungry isopods can easily overtake and eat your velvets. Now springtails are an iffy situation. Myself and other experienced keepers have witnessed springtails actively chewing on some of our worms, some keepers lost entire colonies due to this. Different keepers tried different species and all the same results. Something I did take note of and made sure to pay attention to was which worms were being attacked by springtails. Never did I witness any juvenile or baby being attacked by springtails. It is always larger adults that seem to be the target. 
Anyone who's kept springtails knows their primary diet is fungi and bacteria. Due to the enviornment velvet worms need to survive and their soft skin, this makes them very susceptable to fungal infections. Like I said before, it was always older animals being attacked. One thing that holds true among every living thing is older animals have weaker immune systems leaving them more prone to getting infections. It's my belief that the springtails are eating the fungus off the worms, but not just stopping once the fungus is all gone. Even without springtails to eat away at them, fungal infections quickly spread from animal to animal and cause spontaneous abortion while killing the velvet worm. A small bit of mold in an enclosure is an immediate risk to the health of your colony. I wholeheartedly belive being on top of the overall health of the enclosure is the key to keeping a healthy long term colony.
Now that you have a better understanding on what it's like to care for these animals, I hope potential keepers will make sure to have everything correctly setup before deciding to take on the rewarding challenge of breeding Epiperipatus barbadensis.