Tuesday, January 29, 2008

Sea stars

I have always thought there is only one kind of sea stars and they all have five arms. I mean, come one, isn't that what cartoon and clip art sea stars usually look like?

Well, most of the sea stars I see are six-armed. So I was quite excited to find a five-armed sea star when I took a walk on the Monkey Mia beach one morning.

You can find a five-armed, six-armed, seven-armed, eight-armed, up to fourteen-armed sea star, depending on the species. That's what Graham J Edgar's book 'Australian Marine Life' (2000) says. Interesting.

And you must have heard about the ability of sea stars to regenerate a lost arm. Well, some websites say that if you ever try to kill a sea star, you don't want to chop them up into pieces and chuck them back into the water. These might regenerate to make more sea stars.

So what can you do to get rid of them? You can poison them with copper sulphate and sodium bisulphate! You can inject them one by one.

In general, sea stars can regenerate a lost arm. But that's no big deal. There is a group of sea stars that can do better - Linckia starfish, which was named after JH Linckia, a 18th century naturalist.

The Linckia starfish can regenerate a new starfish from a single arm. So you will first see a funny looking starfish with one big arm and four little arms before the little ones grow bigger. That means they can forget about sex and still make a new sea star.

Some people actually keep Blue Linckia starfish as a pet! A website sells them for 12 to 28 US dollars depending on size. Keeping a sea star as a pet - maybe I would like to try that one day.

Note: If you are interested, check out these websites:
http://www.reef.crc.org.au/publications/explore/feat45.html#t5-2 http://www.susanscott.net/OceanWatch2001/may25-01.html http://oceanlink.island.net/ask/echino.html#anchor21187

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