Visiting Scientist Feature: Dr. Alexander Ziegler

Last week, we welcomed a new visitor to the museum!

Hailing from the University of Bonn in Germany, Dr. Alexander Ziegler studies sea urchins as well as other marine invertebrates. In particular, his research focuses on the internal anatomy of sea urchins.

Dr. Ziegler at his workstation in one of our research labs.

Traditionally, researchers focus on the external morphology (such as the shell and spines) of sea urchins in order to tell different species or larger groups apart.

However, with new technological advancements, it is possible for researchers such as Dr. Ziegler to examine the internal anatomical structures without dissecting the specimen.

Using three-dimensional (3D) imaging systems, researchers are able to generate 3D data of the specimen under study – allowing them to examine the internal anatomy without ‘destroying’ the specimen by cutting it up.

There are multiple methods of doing this, and one of them is via magnetic resonance imaging (MRI) – the same type of technology used to scan humans commonly found in hospitals.

Example of a MRI scan: horizontal section through an unstained sea urchin specimen showing calcified structures such as test and spines (black) versus internal organs such as digestive tract and musculature (dark grey). Photo: Dr. Alexander Ziegler.

Other ways include dyeing the specimens with heavy metals (such as tungsten), in order to generate images of the soft internal anatomy by using a technique called micro-computed tomography (µCT). Dr. Ziegler calls this the “non-destructive but invasive method” as while the specimen is still intact (i.e., not dissected), it is nonetheless invasive as the internal organs have been dyed.

Example of a µCT scan: longitudinal section through a tungsten-stained sea urchin specimen showing external and internal organs. Photo: Dr. Alexander Ziegler.

A comprehensive overview of these imaging techniques is provided in a recently published open access article (click here to read).

Before arriving here, Dr. Ziegler spent six weeks along the coast of New Zealand collecting sea urchin specimens. He decided to make a stopover in Singapore before going back to Germany after Prof. David Lane—one of our honorary research affiliates—recommended that he take a look at specimens in our Zoological Reference Collection (ZRC).

During his 4-day visit here, Dr. Ziegler examined and identified various sea urchin specimens in the ZRC, including those collected from the Comprehensive Marine Biodiversity Survey (CMBS) project, and the SJADES deep-sea expedition.

He also borrowed specimens to bring them back to Germany for 3D imaging.

Although Dr. Ziegler’s visit here has come to an end, his work still continues. He is working with Prof. Lane on a scientific article featuring sea urchin diversity in Singapore, compiling an updated list of the species that can be found locally. This research is primarily based on specimens found in the ZRC.

Dr. Ziegler and Prof. Lane (right) in one of our research labs.

We wish them all the best in their research!