Sea squirts

[Mark Siddall]

In article <2p12pf$afh at sbi.sbi.com> bet at std.sbi.com (Bennett Todd) writes:
>In article <CoB537.LoC at cix.compulink.co.uk>,
>Ian Tresman - IBM Helpwa <helpware at cix.compulink.co.uk> wrote:
>>Can you help? I've been challenged to find the answer to this question:
>>What happens after the sea squirt digests its own brain? I'm French and
>>don't even know what a SEA SQUIRT is... S'il vous plait, aidez-moi! 
>
>Dunno. The only reference I've heard to a Sea Squirt is the following
>paragraph, and I don't know where it came from:
>
> ``The juvenile sea squirt wanders through the sea searching for a suitable
>   rock or hunk of coral to cling to and make its home for life. For this
>   task it has a rudimentary nervous system. When it finds its spot and
>   takes root, it doesn't need its brain anymore so it eats it. It's rather
>   like getting tenure.''

I believe sea-squirts are, in general, tunicates aka ascidians, which
are chordates (though not vertebrates of course).  They are called
"sea squirts" on account of their expelling water from their syphons when
handled.  They have two syphons, one for IN, one for OUT.
Other common names are "sea-potatoe" and "sea-peach" for two that 
are found on the Canadian Atlantic.

tunicates = subphylum Urochordata (prev. Tunicata)

Although the well developed dorsal nerve cord of larval tunicates is
lost during metamorphosis to a cessile adult, I have no knowledge regarding
it being "eaten" as-such.

Mark

-- 
Mark Siddall             The greatest obstacle to discovery is not ignorance,
Department of Zoology       - it is the _illusion_ of knowledge.
University of Toronto                             D. J. Boorstein
mes at zoo.toronto.edu