Holothuroidea: relationships and skeleton evolution
I'm also interested in the evolution of convergent body plans. Echinoderms are defined by their unique skeleton, an intricate mesh of calcium carbonate (CaCO₃). Compared to other echinoderms, whose plated skeletons still form a rigid overall body shape, sea cucumbers took a radically different path: they evolved a worm-shaped body with a fully internal skeleton made of tiny ossicles and a ring of plates near the anterior end, the calcareous ring.
In partnership with my long-time collaborator, Prof. Luciana Martins (MN/UFRJ), I use advanced imaging techniques, including scanning electron microscopy (SEM) and X-ray micro-computed tomography (micro-CT), to study the holothuroid skeleton and its relationship to internal organs.
We described the 3D architecture of the calcareous ring in 10 dendrochirotid species and inferred a phylogeny based on calcareous ring characters. Our results suggest that the complex calcareous ring found in phyllophorids is a derived trait. Incorporating DNA and fossil data, however, will be essential to see the full picture. All 3D reconstructions are freely available online.
Deep-sea echinoderms from sunken wood in the Monterey Canyon, California
In 2011, a Monterey Bay Aquarium Research Institute expedition deployed 28 wood bundles at 3,100 meters depth in Monterey Canyon to investigate wood-fall communities. The bundles were recovered two years later. We are using morphological examination and genome skimming to identify and describe the five echinoderm species collected. I'm conducting this work with recent Stockton graduate Dylan Meier, Dr. Luciana Martins (MN/UFRJ) and Dr. Cristiana Castello Branco (MN/UFRJ).
Range expansion or invasion? Assessing the Status of the echinoid Pseudoboletia on the Brazilian Coast.
Since 2012, specimens of the sea urchin Pseudoboletia have regularly appeared in Brazilian waters, particularly within marine protected areas, but their identity remains uncertain due to a lack of diagnostic morphology and Atlantic molecular data. We found five new occurrences in southeastern Brazil (2019–2021) and are analyzing temporal and geographic patterns.
Preliminary results from COI sequences show Brazilian, Trindade Island, and Gulf of Guinea specimens belong to the same species.
I’m conducting this work with Drs. Luciana Martins (MN/UFRJ), Marcos Tavares (MZUSP) and Guilherme Henrique Pereira-Filho (UNIFESP).
Souto et al. (in prep)
Biodiversity Discovery
Discovering new species is one of the most exciting achievements in science. Every undescribed species holds unique evolutionary history, ecological relationships, and potential value waiting to be understood. Documenting biodiversity, from careful morphological study to molecular tools like DNA barcoding, is essential. Species are going extinct at an alarming rate, and without describing and classifying them, we lose critical information needed to improve conservation strategies, ecosystem management, biotechnology, and human well-being.
