Australasian Science: Australia's authority on science since 1938

Sloppy Barnacle Sex

By Magdeline Lum

What does a barnacle do when its penis isn’t long enough? And how can Coca-Cola save you from gastric surgery?

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In some species of barnacle, the penis is up to eight times the body length. Scientists have thought that the animals’ long penises seek out a neighbour to eject sperm into an egg bearing cavity. After fertilisation the larvae hatch, feed and swim around before settling down near other barnacles.

However, not all species are so well-endowed and their ability to reach a neighbour becomes limited. It has long been thought that since barnacles are hermaphrodites they must be self-fertilised. New research has shown that a short penis does not mean that sexual reproduction is impossible for barnacles, specifically the Pacific gooseneck barnacle (Pollicipes polymerus).

The gooseneck barnacle has a penis of 19 mm in length, which is almost as long as its body. This is hardly long enough to reach an immediate neighbour, let alone seek a partner further along a distant shore. Biologists had assumed that the hermaphroditic barnacle self-fertilised when a mate could not be found.

That is until PhD student Marian Barazandeh of the University of Alberta decided to investigate. There was little data available supporting the self-fertilisation theory and she found that isolated barnacles did not produce any offspring.

Barazandeh observed barnacles leaking sperm at low tide, and wondered whether they were spermcasting. Many fixed marine organisms use...

The full text of this article can be purchased from Informit.