The sophisticated sex lives of sea squirts

Aug 26, 2008
Styela plicata larvae. Image courtesy of Bronwyn Galletly

(PhysOrg.com) -- It may not be pretty, but the humble sea squirt could well be the envy of many: the marine organism never has to worry about contraceptives or IVF.

A UQ study, which is today published in prestigious US journal Proceedings of the National Academy of Sciences, has revealed that sea squirts have a natural ability to control their reproductive cycle, becoming more or less fertile as required.

Lead researcher and PhD student with UQ's School of Integrative Biology, Angela Crean, said the marine organisms could tailor their reproductive cells depending on the level of competition in the sea.

“When there are lots of competing males trying to fertilise the eggs of females, males produce larger, more competitive sperm that live for longer,” Ms Crean said.

“Similarly, when females detect that there are too many males competing for her eggs (too many sperm can kill the eggs of some organisms) the females ‘play hard to get' producing smaller eggs that are harder for searching sperm to find.

“These changes make sense if you're stuck to a rock like sea-squirts are.

“If you can't run away from a highly competitive environment, you must therefore make your gametes more competitive in order to get a higher chance of successfully reproducing.”

The fact that sea squirts don't move made it possible for the majority of the investigation to be conducted in the Moreton Bay field environment.

In a Big Brother-style approach, the primary experiment involved placing a large number of sea squirts in a confined space for an extended period.

“We manipulated adult densities in the field by placing either one (low density) or 15 (high density) sea squirts in a cage for one month,” Ms Crean said.

“This research tells us a little as to how sex evolved in the first place.

“Specifically, it gives us some insight into why sperm are so tiny and males make millions of them whereas female eggs are much larger and are produced in fewer numbers.

“Because these organisms reproduce by the ancestral mode of reproduction, it gives us an indication as to how competition between males led to all sorts of reproductive strategies including the one used by humans: internal fertilisation.”

This research forms part of Ms Crean's PhD, which she hopes to complete by the end of 2009.

Provided by University of Queensland

Explore further: Diabetes drug found in freshwater is a potential cause of intersex fish

Related Stories

DOJ, FBI acknowledge flawed testimony from unit

1 hour ago

The Justice Department and FBI have formally acknowledged that nearly every examiner in the FBI Laboratory's microscopic hair comparison unit gave flawed testimony in almost all trials in which they offered evidence against ...

Dawn glimpses Ceres' north pole

1 hour ago

After spending more than a month in orbit on the dark side of dwarf planet Ceres, NASA's Dawn spacecraft has captured several views of the sunlit north pole of this intriguing world. These images were taken ...

Mountain of electrical waste reaches new peak

1 hour ago

A record amount of electrical and electronic waste hit the rubbish tips in 2014, with the biggest per-capita tallies in countries that pride themselves on environmental consciousness, a report said Sunday.

Recommended for you

York's anti-malarial plant given Chinese approval

14 hours ago

A new hybrid plant used in anti-malarial drug production, developed by scientists at the University of York's Centre for Novel Agricultural Products (CNAP), is now registered as a new variety in China.

The appeal of being anti-GMO

19 hours ago

A team of Belgian philosophers and plant biotechnologists have turned to cognitive science to explain why opposition to genetically modified organisms (GMOs) has become so widespread, despite positive contributions ...

Micro fingers for arranging single cells

19 hours ago

Functional analysis of a cell, which is the fundamental unit of life, is important for gaining new insights into medical and pharmaceutical fields. For efficiently studying cell functions, it is essential ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.