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Observations on the rhizocephalan barnacle Sylon hippolytes M. Sars parasitic on the prawn Spirontocaris lilljeborgi (Danielssen)

1981; Elsevier BV; Volume: 50; Issue: 2-3 Linguagem: Inglês

10.1016/0022-0981(81)90052-6

1879-1697

Jørgen Lützen,

Marine Biology and Ecology Research

A total of 72 prawns, mostly large females of Spirontocaris lilljeborgi (Danielssen), parasitized by the rhizocephalan Sylon hippolytes M. Sars, have been studied. The majority were collected in the Oslofjord, southern Norway (120–200 m). The formation of the root system and nucleus of the parasite have been examined by sectioning and dissection. The smallest internas found in the pereion of the host grow around the hepatopancreas and gonad and later penetrate into the pleon along the intestine and ventral nerve cord. The growth of the nucleus takes place in a tumour under the nerve cord, and when ≈ 3 mm in diameter, the externa breaks through the skin of the pleon at an ecdysis, at which the prawn changes to the breeding dress. It is postulated that male cyprids inject spermatogonia into non-ovigerous externas and that the male germ cells multiply and mature in the ovary at the expense of some of the ova. There is only one oviposition, at which ≈ 20000–200000 eggs are laid more or less simultaneously. Following the emission of the cyprid larvae, the externa degenerates and ultimately falls off, leaving a scar on the pleon. The remaining root system probably does not regenerate a new externa. The effects of parasitism on the host and the cause of frequently occurring multiple infections are discussed.