the adult. Porcelain crabs have two or three larval stages, in which the rostrum and the posterior spine on the carapace are "enormously long". Hermit crabs pass through around four larval stages. The post-larva is known as the glaucothoe, after a genus named by Henri Milne-Edwards in 1830. The glaucothoe is long in Pagurus longicarpus, but glaucothoe larvae up to are known, and were once thought to represent animals which had failed to develop correctly. Like the preceding stages, the glaucothoe is symmetrical, and although the glaucothoe begins as a free-swimming form, it often acquires a gastropod shell to live in; the coconut crab, Birgus latro, always carries a shell when the immature animal comes ashore, but this is discarded later. Although they are classified as crabs, the larvae of Dromiacea are similar to those of the Anomura, which led many scientists to place dromiacean crabs in the Anomura, rather than with the other crabs. Apart from the Dromiacea, all crabs share a similar and distinctive larval form. The crab zoea has a slender, curved abdomen and a forked telson, but its most striking features are the long rostral and dorsal spines, sometimes augmented by further, lateral spines. These spines can be many times longer than the body of the larva. Crab prezoea larvae have been found fossilised in the stomach contents of the Early Cretaceous bony fish Tharrhias. Maxillopoda Copepoda Copepods have six naupliar stages, followed by a stage called the copepodid, which has the same number of body segments and appendages in all copepods. The copepodid larva has two pairs of unsegmented swimming appendages, and an unsegmented "hind-body" comprising the thorax and the abdomen. There are typically five copepodid stages, but parasitic copepods may stop after a single copepodid stage. Once the gonads develop, there are no further moults. Parasitic copepods Chalimus (plural chalimi) is a stage of development of a copepod parasite of fish, such as the salmon louse (Lepeophtheirus salmonis). Chalimus Burmeister, 1834 is also a synonym for Lepeophtheirus Nordmann, 1832. Facetotecta The single genus in the Facetotecta, Hansenocaris, is only known from its larvae. They were first described by Christian Andreas Victor Hensen in 1887, and named "y-nauplia" by Hans Jacob Hansen, assuming them to be the larvae of barnacles. The adults are presumed to be parasites of other animals. See also Ichthyoplankton Marine larval ecology References Crustaceans Larvae