Friday, February 8, 2013

I *crab heart* you!

Valentine's Day is coming up, which means it's time for another crustacean-themed card for your sweetie! I was thinking about crab hearts a while back (when discussing pain in crustaceans) and realized they're just as beautiful as the fake hearts we see everywhere around this time of year!

 The blue really catches the eyes, but check out that fun shape!
(drawing from here)

Inspired by the ol' crab circulatory system, I decided to keep this year's Valentine's Day card simple and sweet:

To make your own, simply download the pdf here, print it out, fold in half, then write something sweet or snappy inside! Your loved ones will love it!

You may be asking yourself: what are those little holes in the crab heart drawing? Those are the ostia (singular = ostium) through which hemolymph, or crab blood, is pumped. When the heart is in its relaxed state, the pores open and pull hemolymph in. The hemolymph gets oxygen, then the heart pumps it back out to all the crab innards and extremities to deliver that oh-so-important O2. You see, crabs have an open circulatory system, as opposed to people: blood just goes everywhere and isn't limited to blood vessels like mammals (which is why it was so easy for me to take hemolymph samples, but you wouldn't want to count on me drawing your blood). In my mind, a card with a crab heart representing an open circulatory system is WAY better than one of those "Keep an open heart" necklaces Jane Seymour's been peddling! And you can quote me on that!

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