Naturespeak A naturalist's view of the world

April 16, 2009

Hey, Hey We’re the Monkeys

Filed under: Uncategorized — wykes @ 9:16 pm

It would be a logical assumption, based on the name alone, to deduce that Fairy Shrimp are extremely delicate in nature. All shrimp (apart from the oxymoronic jumbo type) are little and fairies are gossamer fleeting sprites. Any creature bearing these combined names must have the constitution of frost on a warming day. Right? Not right. In their relative space and time, Fairy Shrimp are titanic and as tough as nails. The very fact that they exist is a testament to this latter fact.

Every spring, when melt and rain water temporarily fills woodland depressions, these vernal pools are instantly populated by a whole fleet of micro-crustaceans. These life forms spring into spontaneous existence as if popping out of the ether itself. When the pools dry up later in the season, the residents vanish as the spots become bone dry. Eastern Fairy Shrimp, crustaceans in a group known as the Branchiopods, are actually among the largest members of this fleet. They are barely over an inch in length, yet are behemoths in relation to the other micro-crustaceans about them.   

True to their name, however, Fairy Shrimp are sporadic (just like Tinkerbell) and you never know whether they’ll put in an appearance from spring to spring. Because they seem to come and go like magic, they are given the Fairy desigantion. There are over 200 species world-wide, but the most common in our neck of the woods is the Eastern variety. I recently encountered some of these facinating spring animals in a vernal pond at Crosswinds Marsh and scooped some up for examination.

I’m really not sure if they were in that pool last year but this year I looked for them and was rewarded for the effort. When free swimming (see title picture) they travel about at an even, but slow, rate of speed and they do so while upside-down. Their slender shape, constantly flapping swimmerets, and bulging red eyes (see here) are their most apparent feature when in this pose. In hand (see below), they appear almost like salmon fry. The pink coloration combined with a definite “tail” and a dark intestinal line running down their back certainly enhances this fishy look.  They are, never-the-less,  crustaceans and so exhibit the segmentation typical of that group. 

The head is made up of two segments where the antennae, eyes and large mandibles originate. The thorax consists of 11 segments each equipped with a pair of multilobed swimmerets and the long segmented “tail” ends in a two pronged appendage (see below). In practice, the swimmerets are responsible for generating a flow of water that brings bacteria, algae, detritus, and protozoans up to the mouth. They eat as they go, so to speak.

You can tell the females from the males since males have larger antennae and the females carry egg cases at the base of their thorax.  Fairy Shrimp are rather fragile as adults, but their eggs are not. The first generation of eggs, those laid over the first month, are thin-shelled. These are produced, laid, and hatched in short order. The second generation, those laid just before the pools dry up, are thick-skinned and drought resistant. After the last drop of water evaporates and the bodies of the adults are rendered into dust, these second generation eggs remain in the soil.

Over a normal cycle of seasons, the eggs will remain dormant for 6-8 months. They hatch out, like magic, when re-immersed in water the following spring. Given a set of abnormal circumstances, these eggs can remain dry and viable for as long as 15 years or more! Now, that’s tough.  Because of this, the eggs – which are actually cysts with fully developed embryos inside – are better considered as sleeping shrimp capsules. Or, better yet, as “instant life crystals” that have the potential to become “Instant Pets.”

As “instant life crystals” Fairy Shrimp eggs are still shipped around the world as Sea Monkey eggs. Yes, you’ve probably seen those ads that used to be on the back of comic books that showed a happy little family of naked pink monkeys swimming happily about their fish bowl kingdom. Some of you may even have ordered the little castle set-up that went with the mail-order set.  All of you were no doubt disappointed when the things that hatched out bore absolutely no resemblance to primates or anything remotely cute. 

Today, you can still order these little miracles from the official Sea-Monkey web site (no, I’m not kidding) but you really don’t need to pay for the experience. Free Sea-Monkeys are currently reigning over a spring pool near you.

2 Comments »

  1. I always wanted to send away for those sea monkeys as a kid, but I always spent the money I had saved up on something else. I am very interested in this as I am going to go and look at some of the pools that occur in the wetland woods behind our house. This gives me a great place to start. Gee, kids would love this type of thing. Maybe some of the neighborhood kids would put down their video games long enough to take a look….

    Comment by ramblingwoods — April 16, 2009 @ 9:31 pm

  2. EXACTLY what I’ve been looking for! Thanks so much!

    Comment by world cup 2010 betting odds — June 15, 2010 @ 2:56 am

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