Carrier's constraint

Carrier's constraint

Carrier's constraint is the observation that air-breathing vertebrates which have two lungs and flex their bodies sideways during locomotion find it very difficult to move and breathe at the same time, because:
*the sideways flexing expands one lung and compresses the other.
*this shunts stale air from lung to lung instead of expelling it completely to make room for fresh air. [cite journal
title=The evolution of locomotor stamina in tetrapods: circumventing a mechanical constraint
volume =

Consequences of Carrier's constraint

Most lizards move in short bursts, with long pauses for breath.

Around the Late Triassic period, animals with Carrier's constraint were preyed on by bipedal species that evolved a more efficient stride

Ways of avoiding Carrier's constraint

Partial solutions

Sea snakes have only one lung.

Monitor lizards increase their stamina by using bones and muscles in the throat and floor of the mouth to "gulp" air. [cite web | url= | title=Monitor Marathons | date=2003 | last=Summers | first=A]

Crocodilians have three modes of locomotion: crawling for short distances (this sprawling gait is subject to Carrier's Constraint); "high walk" for longer distances (the erect limb posture minimizes sideways flexing); "gallop" in emergencies (avoids Carrier's Constraint but they can only gallop for a few seconds).

Complete solutions

Birds have erect limbs and rigid bodies, and therefore do not flex sideways when moving. In addition many of them have a mechanism which pumps both lungs simultaneously when the birds rock their hips.

Most mammals have erect limbs and flexible bodies, which makes their bodies flex vertically when moving fast. This aids breathing as it expands and compresses both lungs simultaneously.


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Constraint — is an element factor or a subsystem that works as a bottleneck. It restricts an entity, project, or system (such as a manufacturing or decision making process) from achieving its potential (or higher level of output) with reference to its goal.… …   Wikipedia

  • U.S. Carrier Group tactics — Naval tactics have played a crucial role in modern battles and wars. The presence of land, changing water depths, weather, detection and electronic warfare, the speed at which actual combat occurs and other factors especially air power render… …   Wikipedia

  • Physiology of dinosaurs — Note: In this article dinosaur means non avian dinosaur, since most experts regard birds as an advanced group of dinosaurs. The physiology of dinosaurs has historically been a controversial subject, particularly thermoregulation. Recently, many… …   Wikipedia

  • Archosaur — Taxobox name = Archosaurs fossil range = Early Triassic Recent image width = 250px image caption = Living archosaurs are crocodilians and birds. regnum = Animalia phylum = Chordata classis = Sauropsida subclassis = Diapsida infraclassis =… …   Wikipedia

  • Evolution of mammals — Restoration of Thrinaxodon, a member of the cynodont group, which includes the ancestors of mammals Further information: Evolutionary history of life The evolution of mammals within the synapsid lineage (sometimes called mammal like reptiles )… …   Wikipedia

  • Mammal — For other uses, see Mammal (disambiguation). Mammals Temporal range: Late Triassic – Recent, 220–0 Ma …   Wikipedia

  • Varanus salvadorii — at the Cincinnati Zoo Scientific classification Kingdom: Animali …   Wikipedia

  • Terrestrial locomotion — [ horse an erect stanced unguligrade quadruped with a galloping gait. An animation of photos by Eadweard Muybridge] Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises… …   Wikipedia

  • china — /chuy neuh/, n. 1. a translucent ceramic material, biscuit fired at a high temperature, its glaze fired at a low temperature. 2. any porcelain ware. 3. plates, cups, saucers, etc., collectively. 4. figurines made of porcelain or ceramic material …   Universalium

  • China — /chuy neuh/, n. 1. People s Republic of, a country in E Asia. 1,221,591,778; 3,691,502 sq. mi. (9,560,990 sq. km). Cap.: Beijing. 2. Republic of. Also called Nationalist China. a republic consisting mainly of the island of Taiwan off the SE coast …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”