The Oxygen Uptake and Metabolism of Balanus Balanus Spermatozoa

The spermatozoa of the Crustacea are often atypical, bizarre, and non-flagellated; those of the few species of cirripedes so far investigated are filamentous bodies in which a much elongated nucleus lies lateral to the fibrillar bundle over much of the length of the latter (unpublished work). When ripe spermatozoa of Balanus balanus (L.) Da Costa are teased out of a seminal vesicle into sea water, their movement is usually negligible and certainly in marked contrast to that of many other invertebrate spermatozoa. B. balanus is a hermaphrodite, yet cross-fertilization is obligatory ; the spermatozoa are transferred to the functional female in a copulatory act, after which the operculum tends to remain closed, the animal assuming a quiescent state with little cirral activity. The semen is shed in the form of a white sticky mass which at first has relatively little tendency to disperse in sea water; the semen thus tends to remain within the mantle cavity. Under natural conditions the details of fertilization are difficult to observe but it would seem that the eggs are only brought into the mantle cavity as the result of some stimulus associated with copulation.