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Vertebrate Preservation


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Methods of taxonomic preservation of lower chordates, fishes, amphibia, reptiles and mammals

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Vertebrate Preservation

  1. 1. Vertebrate Preservation M.Raj Associate Professor, Department of Zoology
  2. 2. Preservation Lower Chordates Hemichordata  For narcotization, place specimens in containers of sea water and permit them to expand completely.  Then add, drop by drop over a period of an hour or more enough absolute alcohol to make a 10% solution.  Complete relaxation usually takes from 4 to 6 hours. When insensible the specimen may be killed in 5% formalin.  Specimens may be preserved either in 70% ethyl or isopropyl alcohol or 5% formalin.
  3. 3. Preservation Lower Chordates Urochordata  For narcotization expand specimens in a large volume of sea water and then  add a small quantity of chrom- acetic fixative to the surface of the water. This will diffuse into the water and kill specimens within 30 minutes to 24 hours.  Formalin may be tried in place of chrom-acetic fixative.  The water is then siphoned off without disturbing the specimens and large quantities of chrom- acetic fixative or 5% formalin is added for its preservation
  4. 4. Preservation Lower Chordates Cephalochordata  For fully relaxing the specimens are first placed in 9 parts of sea water and 1 part of alcohol until they die.  They were then transferred to 50% alcohol and gradually moved up to 70% alcohol for long term preservation
  5. 5. Preservation Fishes Killing fishes  Leave the fish in high doses of the anaesthetizing solution. anaesthetized fish relax and can be preserved in a more natural state. Fixation  Specimen, is placed in a wide-mouthed glass, filled with the fixative solution.  Fish should be inserted into jars head first to make them easier to remove from the jars in the laboratory.  Care must be taken not to pack too many fish in one jar. The specimen should float freely in the jar to avoid curling or bending.  Before immersing large specimens, fixative should be injected directly into the body cavity to facilitate penetration and preservation of the internal organs.  Optimum fixation times for fish under six inches in length is one to two weeks. For fish over six inches in length preservation time ranges from two to four weeks
  6. 6. Preservation Fishes Washing  Following fixation, the specimens are thoroughly rinsed and put into 50 % isopropyl alcohol. The decanted formalin can be reused. The specimen can be rinsed by putting the jar under running water. Alternately, the jar is filled with water. After several hours, the water is decanted and fresh water is added. This is repeated for several days until no formalin odor can be detected. If during rinsing, the specimen shows signs of deterioration, it is transferred directly to 50% isopropyl alcohol for final preservation. Preservation  10% formalin - slightly acidic and will de-calcify and soften bony structures. The addition of a buffering agent helps to slow down this process.  Alcohols, such as ethanol and iso-propanol, are also commonly used to fix and preserve fish specimens, especially if skeletal structures such as otoliths are to be examined.  Freeze in dry ice or liquid nitrogen. This is one of the best methods to preserve the colors and tissues of the specimen.
  7. 7. Preservation Amphibia  Fixative – Formalin  Washing – in alcohol to soak out the formalin before transfer. The alcohol should be changed after 24 hours  Preservation- The following solutions are quite satisfactory for preservation; - 5% formalin; - 70% ethyl alcohol or - 40 to 50% isopropyl alcohol.
  8. 8. Preservation Reptiles- Snakes and Lizards Killing  Drowned in warm water, but this is a slow process  Injecting them with 10% Nembutal solution/ ether/ chloroform Fixation - Fixation requires from 48 hours to 1 week.  Small lizards - Formalin injected in the body cavity or through a cut made on the left ventral side of the body.  Larger lizards - should also be injected in each leg segment and just underneath the skin at the base of the tail.  Snakes - injected with 10% formalin every inch along the length of the cavity, or else they are cut on the left ventral surface of the body. These cuts should measure 1 and 2 inches in length, should penetrate into the body cavity and should be about 1 inch apart. Preservation  Small and medium size reptiles - 6% formalin; large specimens - 10% formalin.
  9. 9. Preservation Reptiles – Turtles and Crocodiles Turtles  The specimens are killed by the same method as that of snakes and lizards.  For preserving small specimens, when the specimen is dead the head, tail, and limbs are pulled out of the shell so that they are exposed.  Slits are made between the neck and forelimbs and between the tail and hind limbs. Formalin is injected into the head, neck and limbs.  The specimen is placed directly in a jar with 10% formalin. After several days the solution may be replaced by 6 to 8% formalin solution.  Big sized specimens may be kept as dried or wet dry specimens. Crocodilians  Small specimens should be positioned, fixed and
  10. 10. Preservation Birds  Study skins: The most traditional preparation is a study skin, in which almost all of the body inside the skin is removed and replaced with cotton so that the final result resembles a bird lying on its back with its wings folded. This stereotypic posture was developed to enable many skins to be kept together in cabinets to protect them from insect and light damage.  Complete skeleton: If a complete skeleton is desired a flat skin may be prepared: all bones, muscle, digestive and other soft tissue is carefully removed and the feathers and skin are stretched flat and dried.  ROM: A more recent preparation method pioneered by the Royal Ontario Museum removes all bones for a complete skeleton while also producing a round skin without bill or legs called a ROM.  Shmoo: If one set of wing and leg bones remain with the skin the preparation is called a shmoo in North America.
  11. 11. Preservation Mammals  Entire fluid-preserved animals (for studying anatomy and histology)  Study skins with accompanying skulls / partial skeletons (some bones remain in the skin), for studying pelage colour, hair quality and moulting patterns.  Mounted skins with accompanying partial or entire skeleton (some bones may remain in the skin, dependant on the method of preservation) or freeze-dried specimens,  Entire skeletons, for studying anatomy, geographic variation or for age determination. At least one male and one female skeleton per species is recommended.
  12. 12. Preservation Mammals Field techniques  In field the specimen is preserved in 10 % buffered formalin (tissue - formalin solution ratio of at least 1:12) or 70-90% alcohol.  For preservation in formalin the body cavity can be filled with formalin solution by injection until it is turgid and firm  Some formalin may also be injected under the skin, into the body cavity, larger muscles and organs.  Removal of the intestine prior to storage of the animal in alcohol is recommended
  13. 13. Preservation Mammals Long term storage in fluid - After fixation in formalin, transfer into alcohol is the most desired alternative. For permanent liquid storage of specimens in alcohol, the following procedure is followed.  After fixation in 10% buffered formalin solution the specimen is to be washed by keeping it in slowly flowing water for 24 hours for removal of formalin remnants.  Next, the specimen is kept in distilled water for about 30 minutes. Exchanging the water twice produces the best results.  With the formalin completely removed, the specimen can be transferred into 50 % alcohol for 30 minutes, then into 70% alcohol for some time.  For long term storage in a collection, a final transfer into 80% alcohol is recommended.
  14. 14. Preservation Mammals Skins and mounts  The condition of the specimen will determine whether or not skin or mounted specimen can be prepared.  If for instance decomposition of the skin has loosened the hair of a carcass so much that it can easily be pulled out or removed by rubbing (“slipping” fur), it will be very difficult or impossible to produce a study skin or mounted specimen.  The standard method of preservation for mammals is that of the round mount for small mammals and the tanned pelt for larger specimens.  The taxidermy mount i.e., life like pose is not used in museum collections, since each specimen requires much more space for storage.  Very small mammals such as shrews can be preserved in liquid and dried.
  15. 15. Preservation Mammals Preparation of skins in the field  After removing the skin from the animal, as much flesh as possible should be removed, but without damaging the skin with hair roots.  Then the skin can be dried in the sun, or if necessary, high over a fire, either hung on a line or stretched between pegs.  Salting the skin will speed the drying process and temporarily preserve the skin. Areas that still have flesh or fat should be salted thoroughly.  Powdered borax can be put on the skin to further preserve it - alternatively cold ashes from a fire can be used.  When the skin is nearly dry, it should be folded with the hairy sides together
  16. 16. Preservation Mammals Laboratory preparation of skins earlier dried in the field It consists of  Relaxation of the dry skin by soaking it in lukewarm tap water, usually over night.  Brief washing of the relaxed skin with soap and water.  Rinsing of the skin in a degreasing agent such as varsol or carbon-tetrachloride; if greasy, the skins are allowed to stand in it for half an hour or so.  Drying of the skin in sawdust, using compressed air to assist the drying and to blow the sawdust out of the hair.
  17. 17. Preservation Mammals Preparing skeletons  The first step is to remove as much of the flesh from the bone as manually possible.  The specimens can be further processed using a variety of techniques including: - enzyme solutions /maceration (with and without heat, detergents, ammonia, or bleaches)/burial in sand, soil, or manure/ dermestid beetle colonies  After any of these treatments, further rinsing and some hand cleaning may be necessary.  If cleaned by beetles, the specimens usually are fumigated, frozen, or rinsed in alcohol to kill the insects.  Then the bones may be soaked in ammonia or chlorine bleach solutions to deodorize. The resulting specimens are then dried (with or without heat).  Sometimes large long bones are drilled and the marrow is removed to reduce the potential for migration of fats and oils out of the bone.