Biodiversity comes in all shapes and sizes

MSU's blog | Created 10 years ago

When you think of a biodiversity survey, you might imagine a group of scientists going off to remote places, climbing mountains, scaling cliffs, or diving to deep coral reefs.  You may imagine a checklist that contains sighting of large mammals and birds, or of rare lizards and frogs…

But sometimes you miss what’s right in front of you. Or what you might be walking on right now! As part of our conservation systematics work in the Pilbara region, we will be making sure we look for the less noticeable inhabitants of our planet too. In the terrestrial realm, this might include digging and sorting through leaf litter to find tiny pseudoscorpions, or even sifting through sand to find tiny snails.  And it is these micro-gastropods that we are talking about today.

In preparation for an upcoming field trip, we wanted to train new staff in how to collect these animals, and test some new photographic gear we have ready for the trip. Because these animals can be so small (less than 1 mm) we have a special camera attached to a microscope to make sure we can record what they look like alive.

The collection technique involves a very high tech piece of equipment known as a rubbish bin (!!). We put a sand, gravel or algal sample into the bin, add lots of water, and swirl it around. Like the whirlpool you used to make in a swimming pool with your friends, small things get pulled into the middle and are held up in the water, and heavier things fall to the bottom. So after we swirl our sample vigorously, we let the sand drop away and quickly pour out the water into a sieve. The animals (which we can’t see yet) get caught on the sieve, and we wash that into a bag to sort through later under a microscope.

We tested out techniques at Cottesloe Beach recently, and found some little beauties! Here is an example of one of the snails we found with a microscope. Although it looks big here, it is around 1mm in length.

Because of their small size, and in this case, a simple shell, molecular data can help us identify these animals with much more certainty than through morphology alone. But being small brings its own challenges for molecular work – it is difficult to take only a small part of tiny animals for extracting DNA. Sometimes we take just a small tissue sample, or use the entire specimen. Luckily, this snail will also leave its shell behind after extraction, as a record of what it used to look like.