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Marbled Cellar Spiders with Egg Sac - Holocnemus pluchei - male - female

Marbled Cellar Spiders with Egg Sac - Holocnemus pluchei - Male Female
Rio Vista, Solano County, California, USA
November 8, 2016
It's not unusual to find a single marbled cellar spider carrying her egg sac, but this was the first time I've ever observed two adults with a single egg sac. They were on my front porch, so it was easy for me to check on them periodically for a couple of days until the spiderlings hatched. The adult on the right is still with the spiderlings, but the other one is very close by. I didn't observe any aggressive behavior, so it would appear that both adults were guarding the egg sac. Could the adults be "mommy" and "daddy" longlegs? These spiders don't appear to be as sexually dimorphic as some other species, but the individual on the left does have slightly larger and darker palps. Is that one male? If any spider experts out there are willing to shed some light on this behavior, I would greatly appreciate it. Species ID is based on the dark ventral abdominal stripes, overall pattern, and long legs.


The one on left is an adult male. He appears to be consuming one of the 'eggs' in this image.

The dark spots on sac are the abdominal portion of the spiderlings with head and legs clearly visible in front of them.

The maternal care ends when spiderlings emerge and female discards sac.

Male probably waiting to mate with female soon after sac discarded, or just using her web for now as a place to stay. Likely a completely different male that mated with her originally.

When females are carrying sacs, and a male is present, males sometimes capture prey caught in the females web (and even when females aren't carrying sacs). I can't remember if females carrying sacs capture prey or not. I'm thinking they simply attach the sac in the hub area during prey capture and consumption, and quickly grab the sac at the slightest disturbance.

for all the helpful information. I didn't really have high hopes that there was any kind of fairy tale family dynamic going on here. It just seemed odd to me that the female didn't appear to be doing anything to defend her young.

are often very tolerant of each at least when conspecifics, and conspecifics are often found in close proximity with interconnected webs. May not apply to all Pholcids, but most of the commonly encountered ones.

So in this instance not odd or unusual as it would be with the majority of spiders out there!

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