Do spiders have a heart?

Haven’t you read “Charlotte’s Web”?  Of course a spider has a heart!  They look after piglets and ensure that they become “some pig”!  Biologically, a spider does have a heart but not really as we know it!  The spider heart is much simpler than the human one.  It is a tube that is positioned at the back of the abdomen.  There it is, below.

Image Credit Wikimedia

Openings on either side of the heart, called ostia, allow blood in to the heart and pump it back out.  The spider has a valve system and that means it can take up any position it wants without the blood going the wrong way!  It can go upside down, sideways – any way it wants without the ‘red stuff’ gushing out!