Those Little Crabs

One of the neatest things to do at the beach is turn over a rock and look for those little crabs. It is so much fun that even adults cannot resist the temptation to flip over a rock or two.

So what are these things? Are they baby crabs that will grow large or are they just little crabs that never get very big. Contrary to what many believe, these are not the young of larger ocean crabs, but are simply small sized species. Under most rocks on Puget Sound shores you can find tiny shore crabs ranging in size from smaller than a fingertip to about the size of a half-dollar.

These small crabs are called purple shore crabs and they can be found on beaches from Alaska to the north to California to the south. They are often found under rocks because they feel safe there. They can range in color from greenish yellows to deep purples. They are certainly fun to watch but be careful; those little claws can pinch your finger.

What do these critters eat? They primarily eat sea lettuce and other green algae. Sometimes, they also eat small dead animals. Scientists classify these crabs as scavengers and, like any scavenger, these crabs are essential in maintaining a stable habitat and a clean beach.

In Puget Sound, females carrying eggs are found from January to mid-July; especially in April. A single female may carry from 400 to 36,000 eggs. Wow, 36,000 eggs – that is a lot of eggs!

If you visit a beach and look for these crabs, be careful not to harm them. Be very careful when you turn over a large rock that you do not crush the crabs. Also, if the rock is large, it is probably better not to try to put it back because you might hurt one of the crabs. Remember that while it is fun to investigate these little creatures, they play an important role in the health of Puget Sound.

I Wonder ...

• These crabs are called scavengers. I wonder what a scavenger is and if there are other animals or birds around Puget Sound that are also classified as scavengers.
• I have also heard of a crab called a hermit crab. I wonder if the hermit crab and the purple shore crab are actually the same creature.
• These crabs seem to be able to walk around on the beach. I wonder how they can breath under the water and also walk around on the beach were they are not under water.

M. Tiller