4 research outputs found
Characteristic Sizes of Life in the Oceans, from Bacteria to Whales*
The size of an individual organism is a key trait to characterize its physiology and feeding ecology. Size-based scaling laws may have a limited size range of validity or undergo a transition from one scaling exponent to another at some characteristic size. We collate and review data on size-based scaling laws for resource acquisition, mobility, sensory range, and progeny size for all pelagic
marine life, from bacteria to whales. Further, we review and develop simple theoretical arguments for observed scaling laws and the characteristic sizes of a change or breakdown of power laws. We divide life in the ocean into
seven major realms based on trophic strategy, physiology, and life history strategy. Such a categorization represents a move away from a taxonomically oriented description toward a trait-based description of life in the oceans.
Finally, we discuss life forms that transgress the simple size-based rules and identify unanswered questions
The 2019 motile active matter roadmap
Activity and autonomous motion are fundamental in living and engineering
systems. This has stimulated the new field of active matter in recent years,
which focuses on the physical aspects of propulsion mechanisms, and on
motility-induced emergent collective behavior of a larger number of identical
agents. The scale of agents ranges from nanomotors and microswimmers, to cells,
fish, birds, and people. Inspired by biological microswimmers, various designs
of autonomous synthetic nano- and micromachines have been proposed. Such
machines provide the basis for multifunctional, highly responsive, intelligent
(artificial) active materials, which exhibit emergent behavior and the ability
to perform tasks in response to external stimuli. A major challenge for
understanding and designing active matter is their inherent nonequilibrium
nature due to persistent energy consumption, which invalidates equilibrium
concepts such as free energy, detailed balance, and time-reversal symmetry.
Unraveling, predicting, and controlling the behavior of active matter is a
truly interdisciplinary endeavor at the interface of biology, chemistry,
ecology, engineering, mathematics, and physics. The vast complexity of
phenomena and mechanisms involved in the self-organization and dynamics of
motile active matter comprises a major challenge. Hence, to advance, and
eventually reach a comprehensive understanding, this important research area
requires a concerted, synergetic approach of the various disciplines