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?

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 spermcasting to reproduce where sperm is released into the water for hermaphroditic mates to capture.

A total of 37 individual barnacles with fertilised egg masses were collected. These individuals were multiple body lengths apart from one another – well beyond the reach of their neighbours’ penises. Barazandeh performed a paternity test on the egg masses. Nearly all of them contained DNA from another barnacle. Sperm was travelling through the water.

It is a sloppy method of reproduction but it may prompt reworking of population models as barnacles may be able to use ocean currents to cross-fertilise.

Blocked Stomach? Drink Coke
Since 1886, when a pharmacist formulated Coca-Cola, the company has never revealed its recipe. Whatever it is, the combination of chemicals in Coke causes it to behave like gastric acid, which helps digest food.

The dentist’s warning that the soft drink’s acidity is harmful to teeth has a ring of truth. But it is this acidity that enables Coke to help clear stomach blockages.

Phytobezoars are a type of trapped mass in the stomach. They are made up of indigestible plant material such as fibres, skins and seeds. Researchers at the University of Athens reviewed reported cases of Coke used to treat phytobezoars in the past 10 years. Of the 46 patients in the sample, 91.3% of patients treated with Coca-Cola avoided surgery.

“Exactly half saw the drink destroy the blockage completely and a further 19 only needed non-invasive treatments as a result of Coke’s help,” says the study, which was recently published in the Journal of Alimentary Pharmacology and Therapeutics.

Only four patients needed full surgery after attempts to treat their blockages with Coca-Cola. It does not matter whether the Coke is classic, Diet Coke or Coke Zero. All are effective, which means patients can opt for less sugary versions of the beverage.