Types of collection specimens of an entire animal:
For reference collections, mammals can be prepared as a variety of specimens. The condition of the specimen may determine possible ways to preserve it; 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 most usual types of specimens (based on Nagorsen and Peterson, 1980) are: 1) entire fluid-preserved animals (for studying anatomy and histology; fluid preservation may change the fur colour) 2) study skins with accompanying skulls / partial skeletons (some bones remain in the skin), for studying pelage colour, hair quality and moulting patterns, 3) 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, 4) entire skeletons, for instance for studying anatomy, geographic variation or for age determination (entire skeletons are poorly represented in collections, so Nagorsen and Peterson (1980) recommend preparation of at least one male and one female skeleton per species.
Preservation of specimens in the field
For preserving taxonomic material such as museum study specimens, different preservation methods should be considered. In the field, there may be limited access to materials and equipment necessary, so preliminary preservation with more simple methods may be necessary before final preparation as a permanent collection specimen. Examples: procedures for preliminary preservation of a whole animal Short-term strorage without preservation (of freshly dead animals needed for mounting or skin preparation) In a cold to moderate climate without refrigeration small animals may be stored in the shade for 4-5 hours. After this period, in warmer climate sooner, the viscera will begin to decompose (Hangay, Dinkley 1985) Formalin preservation:
After weighing and measuring the animal and attaching an adequate label (see labelling), very small specimens (up to 100 g) can be fixed whole by submerging them in 10 % buffered formalin (tissue - formalin solution ratio of at least 1 : 12). 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. If hypodermic needles are not available, the body cavity can be opened ventrally by making a slit instead, allowing the formalin to enter. Keeping the mouth open with a piece of wood or cotton may later allow examination of teeth. Then the whole body can be immersed in formalin, in the posture in which it is supposed to stay permanently because it will harden. The ratio of formalin to carcass must be at least 12 to 1 to assure a good fixation. Tissues can be left in buffered neutralized formalin for several months, but formalin hardens specimens; therefore, after fixation, longterm storage in alcohol may be better. After preservation the carcass should therefore be washed in water and transferred into ethanol for permanent storage, see below: longterm liquid preservation (Nagorsen, Peterson, 1980; Munson, 2000; Rabinowitz et al., 2000). Equipment necessary: formalin, buffer, water, scalpel and / or hypodermic syringes, material for permanent labels, containers (not metal containers unless they are acid-proof lined, because corrosion of the metal would discolour the specimen) (Nagorsen, Peterson 1980).Formalin, however, has some disadvantages; for instance it discolours the fur, after a longish immersion, softens the bones (one of us: C. Groves) and prevents further examination for microbiology. Preservation in alcohol:
After weighing, a whole animal can be preserved in a container of alcohol (70-90%). Removal of the intestine prior to storage of the animal in alcohol...