How to select all textarea boxes within a given div in JQuery? (To disable/require all)

How to select all textarea boxes within a given div in JQuery? (To
disable/require all)

I have a project that shows a DIV within a form when a checkbox is
selected, and within that DIV is a a script that could infinitely add text
areas.
What I want is if a a bajillion of these text areas are created, I want to
disable all of them from being submitted with the form, as well as make
them not required if the over arching checkbox is deselected.
Edit: The reason I am specific about the textareas within a given DIV is
because I have text areas elsewhere on the form!
So, how would I select all of the text boxes within a given DIV? Or, by
name? (all of them on a given class (since they're all a part of the
needb1_3[]array)). I've found some code/threads/answers to select input
boxes, radios, checkboxes, but never text areas.
Thanks for any help in advance.
jsfiddle: http://jsfiddle.net/fmdx/rNqwc/1/
HTML:
<div>
<input id="needb1-3customcheck" type="checkbox"
class="schedb1checkboxes[]" data- select="#needb1-3custom">Need
Custom?
</div>
<div id="needb1-3custom" style="display:none; padding-left:40px;">
<div id="customb1_3" style="padding-left:40px;">
<textarea id="needb1_3_1" placeholder="Six Foot Utility..."
name="needb1_3[]" required>
</textarea>
</div><!-- Ending Custom Div -->
<div style="padding-left:40px;"><a id="add_b1_3" href="#"><span>Add
Exception</span></a></div>
</div>
JQuery:
var b1_3customcounter = 1;
$(function () {
$('a#add_b1_3').click(function () {
b1_3customcounter += 1;
$('#customb1_3').append(
'<div><textarea id="need_b1_3_' + b1_3customcounter + '"
placeholder="Six Foot Utility..." name="needb1_3[]' + '"
required></textarea><a class="remove" href="#">Remove</a></div>');
event.preventDefault();
});
});
$(document).on('click', '.remove', function(){
var $this = $(this);
$(this).closest('div').remove();
event.preventDefault();
});
$('#needb1-3customcheck').click(function(){
var collapse_content_selector = $(this).attr('data-select');
$(collapse_content_selector).toggle(function(){
if($(this).css('display')=='none'){
//Do this while the section is hidden
$('#needb1_3_1').prop('required', false);
}else{
//Do this while the section is visible
$('#needb1_3_1').prop('required', true);
}
});
});