The Communal Project series will document my setup of a Moncentropus balfouri communal, starting with the planning and acquisition of both the enclosure and tarantulas and continuing through as they mature. This is the third installment in the series; the first part is “Communal Project Part 1: An Enclosure by Brooklyn Bugs.” and the second part is “Communal Project Part 2: Nine M. Balfouri Slings” .

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How will they adapt to the communal setup?

Now that the nine M. balfouri slings were housed in their new enclosure, it was time to let them settle in and to observe their behaviors. Although I had read plenty of accounts that should have assured me the risk for casualties was minimal, I still worried that that the tiny little slings would somehow turn on each other as they staked out territory and fed. After hearing for years how cannibalistic tarantulas were, it was very difficult for me to subdue the nagging feeling that this wasn’t going to work out.

However, I would soon learn that my fears were completely unfounded.

Within 24 hours, I started to see signs that my new wards would indeed be able to live peaceably. The following details my observations over the first week, including any details I thought were important or interesting.

DAY ONE: The evening they arrived, I decided to offer food right away. For the first meal, I dropped in 10 tiny B. lateralis pinhead roaches. I won’t lie; when I woke up the next morning, I rushed down to check on the communal partially expecting to find signs of spiderling cannibalization. Instead, I discovered that the little ones had been busy the night before, and fine curtains of webbing now covered some of the den entrances and cork bark.

Even cooler, four of the slings were bustling in and out of one burrow opening. Despite having shot off in several directions upon being housed, it seemed that the slings really had started to gravitate to the same den.

I also watched nervously as two slings encountered each other in another corner of the enclosure. At first, I was convinced that the larger of the slings was going to attack and kill the smaller. As they met, he froze, then reached out carefully with his first set of walking legs, almost as spiders do when they sense a prey item nearby. However, the other sling quickly reciprocated by putting out his fist sets of the legs. The two entwined for a bit, much in the same way males and females do when mating, as they continued to feel each other out. Then, about a minute later, they both walked off in different directions.

No attacks.

No bites.

No devoured sling.

I was amazed by the encounter; it appeared that they could differentiate between one of their own species and a prey item. There was no friction whatsoever. After watching many spiders reflexively pounce on anything that moved in their enclosures, I couldn’t help but to feel a bit mind-blown by this development.

As for feeding, I wasn’t sure if any of the roaches were devoured, and there still appeared to be several of them running around the enclosure. The slings either didn’t notice or didn’t care as they continued working on their den. I decided to give it another day to see if I could catch one or more feeding.

DAY TWO: Having seen a few of the roaches I dropped in still roaming around without a care in the world. I worried that some of the slings might not be eating. Remembering that the M. balfouri mothers often kill prey for their young, I killed a large cricket, mashed it up a bit, and dropped it in front of the den entrances. My hope was that I could catch some of this group feeding I had read about.

I popped in to check on the little guys before bed, and was floored by what I saw. Several of the slings were feeding on the cricket at the same time. Even more interesting, there was no fighting or friction between the feasting tarantulas. They very calmly approached the cricket, tore off a chunk of meat, and simply ate their meals.

I also observed that at least FIVE of the slings now occupied the same burrow. They really were purposely gravitating to the same burrow despite having enough space to stake out their own homes. This was true communal behavior I was witnessing, not just a bunch of spiders sharing space because they were forced to.

DAY THREE:  I crept down late at night to see what my communal was up to (darned insomnia), and I discovered that all nine slings were apparently sharing the same den. For a full five minutes, I watched as they moved in, out, and around the single den entrance with at least four of the slings laying down webbing. They weren’t just living together; it appeared that they were cooperating with each other to build their home. AMAZING.

DAY FOUR: Failing to capture the group feeding on film the first time, I dropped another cricket in on the third night hoping that I might be able to get the next meal on video. I awoke early the next morning to discover several of them eating off of the same cricket. Like a buffoon, I sat their ogling this for bit before remembering to record it. By the time I grabbed my phone, a couple of the spiderlings had toddled off. Still, I managed to catch a few of them eating in the video below. Again, there were no spats or fighting to speak of, and the slings obviously recognized the difference between the prey and the other spiders.

DAY SEVEN: It’s official: all of the slings have adopted the center den as their home, and all are living communally in a single den. The amount of webbing in this area has increased with all lending a hand (or their webbing) to the construction. There are now several entrances including the main one, and the slings spend much of their day going in and out of them.

So, I can cross one of my questions off my list.

• Will the slings all gravitate to one burrow?

Yes, they sure will…and cooperate to build it apparently.

Having raised three M. balfouri slings to adulthood that were kept alone, I do have a couple observations:

1. I’ve noticed that these slings are out in the open MUCH more than my specimens kept separately ever were. Although I’d catch mine out and about every so often, they were very skittish and would spend the majority of their time hidden in their burrows. Perhaps my communal subjects will display more of that secretive behavior as they become more mature, but so far they seem to be much bolder than my last specimens. Could this be because they feel more secure when kept communally? I’m not sure.
2. My first batch of slings were very finicky eaters, often going weeks without eating and often refusing prey one week only to indulge the next. They would also be intimidated by normal sized prey items, and I’d have to feed them crickets that were smaller than what I would usually feed slings that size. As a result, they grew slowly often taking several months between molts. These new slings, however, have been eating like machines. I drop a cricket in and they are on it in minutes. Now I’m wondering if these slings will eat more and grow faster in the communal setting.

With these latest developments, I would have to revise my list of question I wanted to answer.

• Will the slings all gravitate to one burrow? An enthusiastic YES for this.
• Do they really eat together and without friction? (I want to catch more feedings)
• Is their any difference in behavior in M. balfouri slings kept communally as apposed to kept individually (I raised three from slings previously)
• Will their ability to get along change as they mature?
• Do M. balfouri slings kept communally eat more and grow fast than those kept alone?

As I move ahead, I’ll look to answer these questions and will post updates whenever I observe, photograph, or film something of interest!

Next up…M. Balfouri Communal Project Part 4: How Many M. Balfouri Slings Does It Take to Eat a Large Roach?