Tube feet

[Playdope]

Hi all,

I'm wondering .... are Echinoderms the only organisms to possess tube feet? If you know of any others, would ya mind sharing.

Thanks,
Jon

 

[Anonymous]

AFAIK, the hydrostatic skeleton thing is unique to echinoderms....why are you asking? Do you have hungry harlequin shrimp?

 

[Playdope]

I specifically need to know whether Echinoderms are the only organisms to have tube feet. I have heard mixed opinions, and it would be nice to know.

 

[Anonymous]

Well, yes, the tube feet are extensions of the hydrostatic skeleton, and Echinodermata is the only phylum to possess them.

I'll have to check my "Invertebrates" book to make sure, and then I can give you a reference to use. Is this for a paper or report or something?

 

[Anonymous]

Echinoderms have no hydrostatic skeleton. This is reserved for organisms such as Cnidaria, Ctenophora, Trematoda, Annelida, etc., who use muscular pressure as a support. Echinodermata use mutable connective tissue and ossicles for structure and support. Tube feet are unique to the phylum Echinodermata. So is the water vascular system that they are a part of.

 

[Anonymous]

Thanks galleon, you're absolutely correct. I mixed up water vascular system and hydrostatic in my head, for some reason. I'll blame it on shots...

I'm still curious why this info is needed...

 

[Anonymous]

Maybe you could answer a stupid question for me, galleon...if the mesoderm in echinoderms forms the exoskeleton, what exactly does the ectoderm become?

 

[Anonymous]

There are other similar systems in nature, such as the suckers on the feet of octopus.

 

[Anonymous]

Maybe you could answer a stupid question for me, galleon...if the mesoderm in echinoderms forms the exoskeleton, what exactly does the ectoderm become?

Hey Matt, The calcified ossicles of echinoderms are considered a true endoskeleton (in fact, the Crinoids have true vertebrae). The ectoderm covers the mesoderm and the ossicles, as a skin-like layer. Most contemporary urchins even have spines (which are modified ossicles) at least mostly covered in ectoderm. So, if you have an urchin that looses a spine, its an open flesh wound.