A zoological specimen is an animal or part of an animal preserved for scientific use. Various uses are : to verify the identity of a (species), to allow study, increase public knowledge of zoology. Zoological specimens are extremely diverse. Examples are bird and mammal study skins, mounted specimens, skeletal material, casts, pinned insects, dried material, animals preserved in spirit and microscope slides. natural history museums are repositories of zoological specimens
Contents |
Birds and mammal specimens are conserved as dry study skins. The skin is removed from the specimen, treated with absorbents and filled with cotton or polyester batting (in the past plant fibres or sawdust). Projecting thin wooden supports inside the bird specimens allow handling.Preparators use owire to support the legs and tail of mammals.Labels are attached to a leg of the specimen with thread. Study skins may be dried with heat or chemicals.
Osteological collections consist of cleaned, complete and partial skeletons, crania of Vertebrates , mainly birds and mammals. They are used in studies of comparative anatomy and to identify bones from archaeological sites. Human bones are used in medical and forensic studies.
In museum collections it is common for the dry material to greatly exceed the amount of material that is preserved in alcohol.The shells minus their soft parts are kept in card trays within drawers or in glass tubes, often as lots (a lot is a collection of a single species taken from a single locality on a single occasion). Shell collections sometimes suffer from Byne's disease which also affects birds eggs.The study of dry mollusc shells is called conchology as distinct from malacology (wet specimens).
Most insect specimens are pinned.The specimen is transfixed by a specially manufactured stainless steel pins called an entomological pin while it is hydrated.As the insect dries the integument grips the pin holding the specimen.The pins enable handling and also bear the data and determination labels. Once dried the specimens are kept in Unit trays.These are open-top boxes with a have a plastazote (foam) bottom. They fit inside glass-topped drawers. European museums use larger card boxes which are glass-topped and stored in metal cabinets. Soft-bodied insects are kept in alcohol (wet collections) or as microscope slide preparations.
"Wet" specimen collections are stored in 70% ethanol (EtOH) with various additives after fixing with 10% formalin. Modern specimens are stored in screw-top glass jars with polypropylene lids if they are small or stored in stainless steel tanks if they are large. Specimens are also stored in 10% formalin.
Minimum data associated with zoological specimens is the place and date of collection, attached to the specimen by a label. Additional information is the name of the collector and the habitat. Tissue from specimens may be saved for genetic studies (molecular data, DNA). Depending on the animal group other data may be included, for instance in bird collections the bird’s, breeding condition, weight, colours of its eyes, bills and legs and nature of the stomach contents.
A single specimen may be a composite of preparations sharing a unique number. An example would be a verebrate with an alcohol-preserved skin and viscera, a cleared and stained head, the post-cranial dried skeleton, histological, glass slides of various organs, and frozen tissue samples. This specimen could also be a voucher for a publication, or photographs and audiotape.
A voucher is a representative specimen of the animal used in a study, such as a specimen collected as part of an ecological survey or a specimen which was the source of DNA for a molecular study.Voucher specimens confirm the identity of the species referred to in the study. They are a backup against misidentification, changing species concepts which mislead results. Type specimens are a special type of voucher specimen used in taxonomy.
Museum zoological specimens may have historic significance for instance the specimens collected by Johann Baptist von Spix and Carl Friedrich Philipp von Martius during their Brazil Expedition (1817–1820) are in Munich Zoology Museum.
Museums make extensive use of models.When these are accurate they are considered to be specimens in their own right. Examples are the glass coelenterates of Leopold and Rudolf Blaschka