Open Access

Petr Dolejš, Kateřina Vaňousová

• The zoological collection of the National Museum, Prague (NMP) contains spirit (juvenile) as well as dry (mostly adult) specimens of horseshoe crabs (Xiphosura). Living horseshoe crabs are of immunological importance due to clotting agents present in their hemolymph. Here we summarize basic data about the mechanism of the immune system of these marine animals and its use in practice – the Limulus Amebocyte Lysate test – including the laboratory assays and handling with the animals. In the NMP collection, 82 specimens (16 dry and 66 spirit) of all four currently recognised living species of horseshoe crabs are present. They were collected in Indonesia, USA and Vietnam in 1872–1998; Limulus polyphemus from the USA is the most numerous species in the NMP. The collection contains no type specimens but three historical mounted ontogenetic series are present. The largest part of the horseshoe crab collection is 55 spirit specimens from the collection of Václav Frič (1839–1916) whose preparations were intended mostly for educational purposes.