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Stomach Oil




The chemical make up of stomach oil varies from Species to species and from individual, but almost always contains both wax Ester s and Triglyceride s. Other compounds found in stomach oil include Glycerol Ether s, Pristane and Squalene . Stomach oil has low viscocity and will solidify into a hard wax if allowed to cool.

It was once thought that stomach oil was a secretion of the proventriculus, but it is now known to be a residue of the diet created by Digestion of the prey items such as Krill , Squid , Copepod s and Fish . It is thought to serve several functions for Procellariiformes, primarily as an energy store; its Calorific value is around 9600 calories per gram, which is only slightly lower than the value for Diesel oil. For this reason a great deal more energy can be stored in oil form as opposed to as undigested prey. This can be a real advantge for species that range over huge distances to provide food to take back to hungry chicks, or as a store for lean times when ranging across the sea looking for patchy areas of prey.

Another important role in some species is as a weapon. Surface nesting petrels and albatross can eject the oil out of their mouths (not nostrils, as has been suggested sometimes) towards attacking predators or conspecific rivals. The effect of this oil can be deadly; the oil can mat the feathers of an attacker leading to the loss of flight or the water repellancy.


REFERENCES

  • Roby, Daniel D, Taylor, Jan R E, Place, Allen R (1997) "Significance of stomach oil for reproduction in seabirds: An interspecies cross-fostering experiment." ''The Auk'' 114 (4) 725-736. {Link without Title}

  • Warham, J. (1976) "The Incidence, Function and ecological significance of petrel stomach oils." ''Proceedings of the New Zealand Ecological Society'' 24 84-93