Fluid pressure provides support: blue crab

1 of 1 Atlantic Blue Crab / Wendy Kavene.. / License

The body of the blue crab functions during exoskeletal molt using hydrostatic pressure.

Biomimicry Taxonomy

	Maintain physical integrity >
	Manage structural forces >
	Compression

Biomimetic Application Ideas

Hydrostatic skeletal support, hydrostatic "forms" for concrete.

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[Collapse all sections] Summary

"The aquatic blue crab Callinectes sapidus maintains mobility by switching to a hydrostatic skeleton ¹⁰ — a fluid-based skeleton that is common in soft-bodied invertebrates ¹¹. Hydrostatic skeletons are arranged so that the force of muscle contraction is transmitted by an essentially incompressible aqueous fluid ^11–13. Muscle contraction increases the pressure in the fluid, causing the deformations or stiffening required for support, movement and locomotion." (Taylor and Kier 2006:1005)

"Like vertebrates, crustaceans usually move their limbs using muscles attached to a hard skeleton--albeit one on the outside of the body rather than the inside. But when a crab sheds its skeleton to grow a bigger shell, the muscles are left without any rigid surface to pull against. How do they do it? William Kier and Jennifer Taylor of UNC-Chapel Hill investigated, and found that, during molting, crabs use hydrostatic pressure to create a stiff structure against which muscles can pull. Fluid pressure in the claw goes up as the muscles contract; if you remove a claw during molting, it deflates like a flat tire. Once the shell has hardened, however, pressure does not change during muscle use. Soft-shelled crabs are the first animals known to use both a skeleton and hydrostatic pressure for support." (Jones 2003:17)

About the inspiring organism

bluepoint
Callinectes sapidus M. J. Rathbun, 1896
[blue crab]

IUCN Red List Status: Unknown

Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Hydrostatic skeletal support, hydrostatic "forms" for concrete.

Industrial Sector(s) interested in this strategy: Construction, packaging, transportation, manufacturing

Experts

The Kier Lab
William Kier
University of North Carolina Chapel Hill

References

Taylor, J. R. A.; Kier, W. M. 2006. A pneumo-hydrostatic skeleton in land crabs. Nature. 440(7087): 1005.

Jones N. 2003. Soft-shelled crabs get all pumped up. New Scientist. 179(2404): 17.

Fluid pressure provides support: blue crab

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