Parasitologists have estimated that parasites comprise over half of all animal species. That said, many regions and ecosystems remain understudied for parasites, despite free-living groups having been routinely sampled; this is especially true for the marine environment.
Over the last 16 years, we have made much progress on documenting the metazoan parasite biodiversity globally, specifically of tapeworms that, as adults, parasitize the digestive tract of sharks and rays. Among the 18 orders of tapeworms currently recognized, seven orders exclusively parasitize sharks and rays. Although more than 930 species of tapeworms that parasitize sharks and rays as adults have been described, it is clear that this number represents only a small fraction of the vast diversity of shark and ray tapeworms that remains to be described. We have concentrated on the orders Lecanicephalidea and Tetraphyllidea, which collectively comprise a total of ~550 species and exhibit strict specificity for their elasmobranch host.
Within this system, major ongoing research involves the investigation of tapeworm morphology, systematics, biodiversity, coevolution, pathology, and life cycles.
In addition, patterns of host associations and geographic distributions are a central focus. Techniques employed to obtain data to address these questions include, but are not limited to, light and scanning electron microscopy, confocal microscopy, histology, and Sanger and Illumina sequencing.