From 2011 to 2015, the Collection Care team improved the storage of many of the Natural Sciences wet collections at Auckland Museum. Some particularly memorable specimens were encountered along the way.

What is a Wet Collection?

When it comes to natural history museum specimens, you have a few options for preserving a specimen. You can choose to preserve the exterior of the object, as is the case with taxidermy. You can dry out the entire specimen, as is common with many botanical collections. Or you can preserve the animal (or plant) in liquid – a Wet Collection.

By preserving a collection item in liquid, you ensure that the entire specimen is retained, giving researchers access to anatomical structures that would be otherwise lost. However, this technique only works if the concentration of the preservative is high enough to prevent deterioration.

How do you prevent deterioration?

There are two steps to the process: fixation and preservation. Fixation binds the proteins so that the specimen doesn't rot. Specimens are stored in 10% formalin (a saturated mixture of 37% formaldehyde gas in water) until all live tissues are "fixed". Preservation is the solution that the specimen goes into after it has been fixed – most commonly alcohol (usually 70% ethanol to 30% water) or a lower concentration of formalin solution (usually 5%, depending on specimen size).

As formalin is highly toxic for people, we prefer to use ethanol. But if exposed to air, ethanol will slowly evaporate out of the solution, leaving behind only water. This allows the natural processes of decay to kick in, which is the last thing that you want in a museum collection. Therefore, the most important aspect of caring for a wet collection is to ensure that it remains wet by maintaining the right chemical concentration to preserve the sample.

What was the project?

In 2011 we designed and purchased an insert to go in the top of a standardised range of wet collection jars. This insert creates an airtight seal, preventing any evaporation. The jar lid is then placed over the insert, securing everything safely inside.

This was a fantastic long term solution. However, it also meant we had to open the lid of every single jar in the Natural Sciences wet collections - entomology, botany, land vertebrates and marine - which includes more than 10,000 jars. If a jar was one of our standard sizes (125ml, 250ml, 500ml, 1000ml or 2000ml), it was a fairly simple job of replacing the preserving liquid, installing an insert, then popping the lid back on.

However, if the jar was a non-standard size, we had to remove all of the specimen(s) and put them into a new, standard-sized jar. While this may sound simple, there were a few particularly interesting objects that made re-jarring one of the most challenging aspects of this project. One example was the frogs from the land vertebrates collection. Their cold, weirdly rubbery, chicken-flesh texture could be felt through the nitrile gloves.

What else did we find?

Over several years, the collection managers in the Collection Care team worked their way through these collection stores, encountering many surprising creatures along the way. Some of our favourite finds included shellfish with really long "tongues", lizards with tails that would fall off at the slightest jolt, a 10-litre bucket of snakes, cave weta with their beautifully delicate feelers, and the jars of vials containing microscopic insects too tiny to see.

Wet Collection challenges

Everyone involved in this rather long project definitely enjoyed their weekly adventures in Natural Sciences!

You can see specimens from the Wet Collection in the Weird and Wonderful gallery.