ARISE's Team Sampling has its ambitious goal of building a reference database of multicellular organisms in the Netherlands. Every week new samples arrive at Naturalis, or already existing specimens are processed, in order to build this enormous database. This week we worked with some marine samples, which are very diverse in diversity, size and techniques necessary to sample them. There are beautiful species among the samples like the Atlantic dwarf squid (Sepiola atlantica) and the green sea urchin (Psammechinus miliaris). However, there are also some stubborn species, like this top snail (Steromphala cineraria) which we had to crack open with a vice.
The marine samples are collected by an expert in the field who is a specialist in marine organisms, especially invertebrates. In the marine environent specimens can be collected in various ways, these include turning rocks in the intertidal zone, snorkeling or even diving. It is not as easy as it may sound, as most of the marine environment consists of large mixed communities. Large oysters have large algae on them, algae have tiny snails on them, tiny snail houses can be occupied by hermit crabs and carry a sea anemone. If you have one specimen it is almost never alone, it hosts a variety of species.
The small stuff
Besides this, you need a very good eye and know what you are searching for. Many species have a specific host, such as the numerous tiny sea slugs we have in the Netherlands. Most of them have a very specific algae, or hydroid as a specific host and you can only find these species by finding its host. Imagine that you are diving, the floor is muddy, and you have to search for a tiny hydroid that’s a few centimeters tall, which is the host of an even smaller sea slug just a few millimeters long. It is that challenging!
Getting to the tissue of an animal can be very challenging like the top-snail which we had to crack open. Many species have evolved in a way to protect themself. In the case of the snail, it creates a thick shell. Imagine species that live attached to rocks and it is nearly impossible to get them off without the sharpest knife, or bivalves that have the thickest muscles to keep their valves closed so that even a hammer won't break them.
Fresh or classic?
Many of these species can also be found in the large natural history collection at Naturalis, however using collection specimens has challenges of its own. A large share of the collection is stored in dry collections. In this case there is no live tissue anymore, which will affect its use for molecular data. The part of the collection that is stored with a preservation on ethanol can be very old, historically important, or even very fragile, therefore it is not always usable for molecular work. Not to mention that it is always the question if we have every species presented with a collecting location within the Netherlands. Many have the opinion that fresh collected material is always better, but during ARISE, pilots will take place in order to identify how much use we can make from the collections.
Text: Hannco Bakker Pictures: Maryse Diekman & Hannco Bakker