Saturday, July 19, 2008

Sea stars on South Beach, Fremantle

I went to South Beach, Freo (Fremantle) this arvo. I didn't expect to see much at first, considering it is near WA's largest port. But I got a few nice surprises - one of which being finding three large sea stars (~ 15 cm or more across) on the shore. I was so excited as I haven't seen one for a long time.

Images 1, 2, 3
(1) This is the first one I saw. It was upside down. (I found the broken tip and put it on the body.)
(2) Close-up of the broken tip. I love the colours.
(3) I turned it and took another shot.

Images 4, 5
(4) The exposed end on the broken tip. The orange color reminded me of the yolk of salted egg.
(5) The exposed end on the broken arm. Look at the tiny tube feet!
Seriously, don't they look like some rice biscuit sticks with orange-flavor filling?

Images 6, 7, 8
Close-ups of the upper side of the sea star

Images 9, 10
This is the second sea star I found.

Images 11, 12, 13
Close-ups of its arms

I think this is Archaster angulata - it looks very similar to the photo in Australian Marine Life by Tassie scientist Graham J Edgar, who works for UTAS. And similar to some photos I found on the net, too.

Anyway, the most striking thing about this sea star is that they make out one "on" one during the breeding season! The two known Archaster species sea stars are believed to be the only ones that do it one-"on"-one.

The male simply goes and sits on the female and as soon as the female spawns, the male will release its sperm. (They seem to have better control than many : ) ) Apparently, other sea stars just come together in a big party and spawn together, hoping that there will be some successful fertilization. Having some body contact is nicer I think.


Mosura said...

Were you hungry when you wrote that thing about the rice biscuits? :-)

I have that book and yes, the picture certainly look just like yours.

Tsun-Thai Chai said...

Ha ha!

Not really. Shouldn't be. Because I was surrounded by piles of smelly, decaying seaweeds where I found the sea stars.

Tsun-Thai Chai said...

Oops, I read too fast.

No, I was not hungry when I wrote that. But I really think that they look like some kind of food with it's filling oozing ;p