[Chaos-l] Tentacles (last one for tonight)

[Jon Stewart-Taylor]

A dictionary definition of "tentacle":

    tentacle (plural tentacles)
	• An elongated, boneless, flexible organ or limb of some animals,  
such as the octopus and squid.

 From the Wiki article (http://en.wikipedia.org/wiki/Tentacle):

> A tentacle or bothrium (plural: bothria) is one of usually two or  
> more elongated flexible organs present in animals, especially  
> invertebrates. The term may also refer to the hairs of the leaves of  
> some insectivorous plants. Usually, tentacles are used for feeding,  
> feeling and grasping. Anatomically, they work like other muscular  
> hydrostats.

Like many, i expect, i thought tentacles were used for locomotion but  
apparently they're not.  On the other hand, that lovely phrase  
"muscular hydrostat" (learn something new every day) is linked (http://en.wikipedia.org/wiki/Muscular_hydrostat 
):

>  A muscular hydrostat is a biological structure found in animals. It  
> is used to manipulate items (including food) or to move its host  
> about and consists mainly of muscles with no skeletal support. It  
> performs its hydraulic movement without fluid in a separate  
> compartment[.]

So, is an elephant's trunk a tentacle?  It's certainly used for  
feeding, feeling, and grasping.  In any case, it is a muscular  
hydrostat (so are tongues, by the way), though it's not used for  
locomotion (neither are tongues, in normal cases).

I'll leave you with a link to an article on robot analogs of muscular  
hydrostats:

    http://blog.makezine.com/2010/04/20/tentacle-robot/

'Night.

J.
-- 
Jon Stewart-Taylor:  joncst at earthlink.net
Chapel Hill Astronomy: http://www.rtpnet.org/chaos
Cape Fear Astronomy: http://www.capefearastro.org/