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Biology/Natural History: Rhizocephalan barnacles such as this species are bizarrely distorted parasitic barnacles. It was not even known that they were barnacles until the cypris larva in their life cycle was discovered. The eggs of Rhizocephalans usually hatch as a nauplius larva which metamorphoses into a cypris larva. Members of order Akentrogonida, however, such as Sylon hippolyte, apparently pass the nauplius stage in the egg and hatch as a cypris. The female cyprid settles onto a recently molted host or attaches to the host gill. She attaches to the host using a glue gland on her antennae. She then metamorphoses, losing her legs and eyes. She extrudes her tissue through the antenna or through her mouth through the host carapace into the host internal tissue. At that point she may be called a "kentrogon" if she is in order Kentrogonida. The injected barnacle grows into a ramifying rootlike structure called an "interna". The interna begins growing by sending out rootlike projections through the body of the host. These projections absorb nutrients from the host, and typically destroy the gonads (a parasitic castrator). The interna may grow very large and may actually become heavier than the host tissue. When she matures, a part of her body called the "externa" erupts through the exoskeleton of the host, usually on the ventral side of the abdomen near the gonads. The externa has a cavity for eggs and a place for males to attach. Male cyprids settle into the externa and metamorphose into a wormlike structure.
Female shrimp which have this parasite species do not bear eggs, so the parasite is probably a parasitic castrator as are many Rhizocephalans.