Trypanorhyncha

Within the class Cestoda, besides the Cyclophyllidea, most other orders are fish parasites. Many primitive cestodes such as the Diphyllidea and Tetraphyllidea are marine group of tapeworms and are common parasites in the spiral valve of elasmobranchs. Of these, the order Trypanorhyncha Diesing, 1863 is among the most species‐rich. More than 260 valid species have been described, and new species are added every year. They infest the stomach and intestine of sharks and rays (Elasmobranchii) as final hosts. Therefore, they have a cosmopolitan distribution and, in accordance to the species‐richness of their final hosts, they belong to the most abundant fish parasites in tropical waters. The larval stages live in various organs of teleost fish and also in marine invertebrates, such as crustaceans, cephalopods, and bivalves. Some larvae have been recorded even from sea turtles, sea snakes, and also from the living fossil Latimeria chalummnae.

Trypanorhynchs have complex, indirect life cycles...