Preparing a Snake Skeleton

 

 

 

 

The skeleton of this 5.8 m (19 foot) Reticulated Python was assembled by Patrick Couper in the Queensland Museum's Herpetology Section. This skeleton, on permanent display at Australia Zoo, took 4 weeks to prepare. The python was a long-term resident at Australia Zoo, Old Pacific Highway, Beerwah. It died of natural causes, in 1995.

Fauna is protected under wildlife legislation and regulations. Permits are required to collect living or dead specimens. Advice on the legal status of specimens and permits should be sought from the wildlife authority.

The snake was skinned and its gut removed. Most muscle was cut from the backbone. The snake carcass was then cut into manageable pieces, each about 60 cm long. This must be done carefully, to avoid damaging ball and socket joints connecting adjoining vertebrae. Wire was threaded through the vertebral canal of each section, to ensure the vertebrae stayed in order as the remaining meat was removed. The carcass was air-dried.

The dried carcass was placed in a box housing a colony of flesh-eating beetles and their larvae (dermestids). These ate away the remaining meat and reduced the carcass to bare bones. The carcass was checked daily and removed before the ribs fell away from the backbone.

Dermestids like to be dry and warm, and in the dark. The litter created by these insects (shed skins and faeces) can trigger allergies in some people. It is important to avoid inhaling this material, or touching it with bare skin. Gloves and a mask should be worn at all times when dealing with these insects.

Once the skeleton was removed from the dermestids, the ribs were gently pulled away from the backbone They were placed in order on a styrofoam sheet and secured with fine stainless steel pins. It was essential to keep the ribs in order and to know where the ribs attach along the snake's backbone. This is vitally important if comparative material is not available to help with the final positioning of bones.

The skeleton was now ready for bleaching. Foam sheets, to which the ribs were pinned and weighted, were placed in a suitable container. The corresponding section of backbone was also placed with the ribs in the bleaching container. The bleaching solution was poured gently into the container, to avoid dislodging the ribs. Care should be taken to avoid skin and eye contact with the bleaching solution. This process should also be carried out in a well-ventilated area. It is safest to use a weak solution and continue the process over an extended period (up to 24 hours). Strong solutions can damage bones. This skeleton was bleached in a tub of hot water and weak sodium perborate (NaBO₃) was added. When the bones were well-bleached, they were removed. Remaining flesh and cartilage was easily scraped away. The bones were then soaked in clean water for 24 hours to remove traces of bleach.

The ribs were attached to the backbone by small, non-corrosive wires. A small hole (1 mm or less) was drilled through the head of each rib and the corresponding attachment points on each vertebra. A short wire was threaded through these holes, connecting each pair of ribs to its associated vertebra. The ends of each wire were twisted together with a small pair of pliers. It was necessary to ensure that the wires were not over-tightened. Retaining movement is important in the final positioning of the skeleton. The preparation of this skeleton required wiring 636 ribs to the backbone and the drilling of 1278 holes.

When all the ribs were attached to the backbone, each vertebra (except those of the tail) was threaded, in order, onto a strong wire that was slightly longer than the overall length of the snake. The tail vertebrae were threaded, in order, onto a smaller gauge wire as well. Only three vertebrae at a time were threaded on to each wire. Every third vertebra was locked into place with small wooden chocks. Small pieces of bamboo meat skewers were ideal. These were packed tightly around the wire, which had been positioned centrally through the spinal canal.

The tail and body wires were then joined together, leaving enough wire protruding forward from the neck, to allow attachment of the skull later.

A suitable base was required (e.g. a log, fumigated or frozen, to kill wood-boring insects). The skeleton was draped over this in a life-like pose. The skeleton was fixed in place with small lengths of mono-filament line. Alternatively, attachment points can be made with short lengths of wire

The ribs were positioned in a life-like pose. Ribs on the inside of a curve are closer together than those on the outside of the curve. Each rib is held in place with a small drop of instant adhesive. This must be done in a well-ventilated area, or with a protective mask. The attachment points were then strengthened with woodworking glue.

Finally, the skull was attached to the skeleton. The neck wire was cut to fit neatly into the cranial cavity. Then a small loop was made at the end of the wire. The cranial cavity with filled with a clear silicon sealant and the skull placed in its final position on the wire. The skull must be taped in position until the sealant dries. Once the sealant has set, the skull can not be repositioned.

Ideally, the skeleton should be housed in a display case to prevent dust from building up on it.

The above procedure, with minor modification, can be used for the preparation of most skeletons. The pig skeleton in this exhibit was also prepared with dermestids.

Watch the flesh-eating dermestid insects in action.