Cells Temporarily Self-repair Ruptures

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Biological Strategy

Fig tree

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Manage Tension

When a living system is under tension, it means there is a force pulling on it, like a person pulling on a rope tied to a horse. When applied to a living system, unless the system is completely rigid, the result is that it gets stretched. If stretching exceeds the strength of the living system’s material, it can damage it. Living systems manage tension using materials that are flexible and stretchable enough to survive most tension that occurs in their environment. The ocean’s intertidal zone offers a good example. The waves and incoming and outgoing tides put tension on soft-bodied organisms. Mussels resist tension with flexible threads that hold them onto rocks; in contrast, large algae have stretchy fronds.

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Prevent Fracture/Rupture

High force impact or stress can cause materials that comprise living systems to separate into two or more pieces (called fracturing) or to break or burst suddenly (called rupturing). For example, a scallop prevents structural failure from fracture because its shell is comprised of two materials of varying stiffness. When a crack moves from the scallop’s stiff material to the less stiff one, the latter reduces the force at the tip of the crack, thereby stopping it from spreading farther.

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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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Cells in the bark of ficus trees temporarily repair ruptures by secreting latex into the wound site which cures upon exposure to air.

After a break or tear in its bark, ficus trees secrete pre-made latex at the site of the wound. When exposed to air, this complex emulsion coagulates into an elastic that serves several defensive functions including halting any further tearing (i.e., increasing tensile strength) and sealing the wound from infection until cell growth can permanently mend the injury. Thirty minutes after the damage is sustained by the ficus, latex has already coagulated enough at the damage site for about 55% of the materials original, un-wounded tensile strength to be restored. This added strength is maintained for hours or days until cellular growth can restore the materials complete strength (latex protects from further tearing but does not provide stiffness). Even before 30 minutes after the injury, when latex is still largely uncoagulated, it serves to support the mechanical properties of the damaged material perhaps acting like a sticky, glue-like substance.

Image: Wouter Hagens /

Last Updated August 23, 2016

References

Journal article

Restoration of tensile strength in bark samples of Ficus benjamina due to coagulation of latex during fast self-healing of fissures

Annals of Botany | 30/12/2011 | G. Bauer, T. Speck

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