Comments on: Sea Urchin video (Guest post from a kid)

By: Glen Able

Glen Able — Wed, 06 Jun 2012 19:15:00 +0000

Thanks, it’s good to know the general idea, although I have trouble visualising in detail how the very curved plate of a tiny urchin becomes part of a bigger less curvy plate (perhaps it thickens?)

I wish those lazy urchin scientists would make me a timelapse.

By: MichaelO

MichaelO — Wed, 06 Jun 2012 17:18:00 +0000

This video was actually pretty good. It had a lot of facts.The pictures were pretty.
Genevieve O’Connell – Hawaii

By: Ashley Reid

Ashley Reid — Wed, 06 Jun 2012 14:45:00 +0000

What a neat video! Thanks for posting this!

By: Lyle Hopwood

Lyle Hopwood — Wed, 06 Jun 2012 14:13:00 +0000

They are analogous to five-armed starfish with the arms sewn together. The area between the “arms” is actually called the “sutural line”. There’s flexible collagen at this line and as the urchin eats, the collagen expands slightly, then the calcite grows into the expanded collagen forming a larger bony plate. Then the urchin eats again, etc.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1690893/pdf/11839189.pdf(PDF)

By: wandermarket

wandermarket — Wed, 06 Jun 2012 13:37:00 +0000

Cool video…thanks for sharing…

By: Glen Able

Glen Able — Wed, 06 Jun 2012 13:24:00 +0000

Nice. But what I can’t figure out about sea urchins is how they grow.

Insects, for example, grow in stages by shedding their old exoskeleton, puffing themselves up a bit and then hardening up again. Other things like snails continually add new shell at the opening, and grow in a spiral. But how do urchins make their hard shell bigger, while managing to stay roughly spherical?

By: Sinead Dowding

Sinead Dowding — Wed, 06 Jun 2012 13:07:00 +0000

My mum used to collect them.It was the coolest

By: Kieran Manners

Kieran Manners — Wed, 06 Jun 2012 12:03:00 +0000

Have you ever seen a Sea-Urchins shell, Sasha?