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| Preservation of animal species |
Preservation can be defined as the use of chemical, physical or other Processes to prevent microbial
and physical damages to biological specimens with a view of retaining their original form and prolonging their storage life.
The procedure for preservation of animal specimens varies greatly from one animal group to another.
In most cases, the animal must first be killed or narcotised in a suitable way so as to leave the tissues in a state ,which is proper for display.
The specimen is then fixed in this condition and finally preserved. This final preservation is normally made either in a solution of ethanol or methanal (formalin).
Techniques in fixing and preserving animal materials
Fixation is a chemical process, which stops autolysis and stabilizes protein components of tissues so that in
subsequent processing the tissue retains as fully possible the form they had in life.
Preservation allows materials to be stored indefinitely by destroying any microbial action, which could degrade the specimen.
The choice of fixation will depend upon the animal material to be fixed and the purpose for which it is being fixed.
Narcotisation :This is also known as relaxation and is an interim technique for animals since many are highly contractile and assume grossly distorted postures if placed straight into fixative.
The main factors to be considered in
Hardening: Some chemical like ethanol is particularly liable to cause tissues to harden on prolonged exposure to high concentration.
Shrinkage :Certain fixatives such as ethanol and mercuric chloride cause tissues to shrink thus distorting the specimen significantly.
Preservation techniques
* A 5-10%v/v aqueous solution of formalin(=40% v tv aqueous formaldehyde neutralized with calcium carbonate to prevent any acidity in the solution resulting in the slow dissolution of calcareous structures.)
*50-70% ethanol : Ethanol is inflammable, highly volatile and tends to cause shrinkage and decolorization in soft bodied animals. Pass them slowly through a graded series of concentrations to minimize this problem.
Dry preservation
This form of preservation is used mainly for vertebrate taxidermy and for arthropods and other invertebrate species. The hard exoskeleton of arthropods are easily preserved in dry state since the skeleton prevents collapse and loss of form upon drying.
Taxidermy : it is a type of dry mounting where the vertebrate is carefully skinned to remove the body and then replace with false body made of polystyrene, foam or cork etc.
Storage : Careful maintenance of specimen after fixation /preservation process is very important. The storage conditions for materials preserved either in wet or dry state.
Labelling : labelling must be comprehensive and contain information on the fixative and preservation processes as well as ecologically and taxonomic details.
Reasons for animal preservation
* it prolongs the storage life of the specimens.*it prevents the attack of micro–organisms like bacteria and fungi that causes spoilage.
* it helps in the preservation of large quantities of specimen needed for laboratory studies.
*extinct animals specimens can be preserved for future study.
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