I am not sure how they survive, but eating their babies would not be sustainable sustenance.
In Movile Cave, Romania, a unique ecosystem exists in total darkness, relying on chemosynthesis rather than photosynthesis. Bacteria there feed on methane and sulfur rising from the Earth’s crust, forming the base of the food chain for over 48 species found nowhere else on Earth, including several types of blind spiders.
Adaptation: These specific spiders have distinct gut microbiomes compared to their relatives above ground, which allows them to process the sulfur-heavy diet that would be toxic to other species.
Diet: Stable isotope analysis revealed that the arachnids in this cave were not eating insects from the outside world but were integrated into the cave’s unique, sulfur-based food web.
Cute.