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Tangled active filaments are ubiquitous in nature, from chromosomal DNA and cilia carpets to root networks and worm blobs. How activity and elasticity facilitate collective topological transformations in living tangled matter is not well understood. Here, we report an experimental and theoretical study of California blackworms (Lumbriculus variegatus), which slowly form tangles over minutes but can untangle in milliseconds. Combining ultrasound imaging, theoretical analysis and simulations, we develop and validate a mechanistic model that explains how the kinematics of individual active filaments determines their emergent collective topological dynamics. The model reveals that resonantly alternating helical waves enable both tangle formation and ultrafast untangling. By identifying generic dynamical principles of topological self-transformations, our results can provide guidance for designing new classes of topologically tunable active materials.

Many types of organisms utilize group aggregation as a method for survival. The freshwater oligochaete, California blackworms Lumbriculus variegatus form tightly entangled structures, or worm "blobs", that have adapted to survive in extremely low levels of dissolved oxygen (DO). Individual blackworms adapt to hypoxic environments through respiration via their mucous body wall and posterior ciliated hindgut, which they wave above them. However, the change in collective behavior at different levels of DO is not known. Using a closed-loop respirometer with flow, we discover that the relative tail reaching activity flux in low DO is $\sim$75x higher than in the high DO condition. Additionally, when flow rate is increased to suspend the worm blobs upward, we find that the average exposed surface area of a blob in low DO is $\sim$1.4x higher than in high DO. Furthermore, we observe emergent properties that arise when a worm blob is exposed to extreme DO levels. Here we show that internal stress is generated when worm blobs are exposed to high DO levels, allowing them to be physically lifted off from the bottom of a conical container using a serrated endpiece. Our results demonstrate how both collective behavior and the emergent generation of internal stress in worm blobs change to accommodate differing levels of oxygen, which could be used to model and simulate swarm robots, self-assembly structures, or soft material entanglements.