Tuesday, December 7, 2021

How to become invisible

If you're a resident shrimp in a tidepool filled with hungry sculpins, you might find it advantageous to be invisible.  So how do you become invisible?

Step 1: Become a color that matches things in the background of the tidepool, e.g., pink like coralline algae:

 
 
Step 2: Add highlights spots and bands of different colors that show up in the background.  For example, white stripes that match the white tips of the coralline algae, and some darker reds that match the shadows:
 
 
 
Step 3: Make some of your body parts look like algae.  For example, you could make your head appendages, or the sides of your abdomen, or the tip of your tail look like the branches of coralline algae.  And you could hold your abdomen and tail in an upright position:
 
 

Step 4: Adapt your behavior to make it hard for a fish to spot you.  For example, stay very still, and only become more active at night.  (Shhhh...no shrimp here!)
 
 

Meet the incredible shrimp, Lebbeus lagunae!  Eric spotted this amazing shrimp while we were tidepooling during the exceptional low tide on 5 December 2021.  It was hard to believe what we were seeing at first.  It's a fantastic example of crypsis avoiding detection by predators via use of colors and patterns and shapes that help to blend in with the background. 

The geographic distribution of this species is typically described as Baja California, Mexico to Monterey, California.  However, we are looking into a possible record from Mendocino County (thanks to Jim!). So this shrimp could be a primarily southern species that is rare here, or it might just be rarely seen here given that it's almost invisible and more active at night.


 
 
Many thanks to Eric for his excellent observation skills!  Now you can imagine these shrimp hiding among the coralline algae in the local tidepools.

2 comments:

  1. This guy is amazing. I never would have believed he was a shrimp if you hadn't illustrated it so beautifully.
    Now I'm wondering how often they get detected by predators? Are they long-lived?

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  2. Hi, Alice!

    I don't know how much is known about the life history of Lebbeus lagunae. Their camouflage likely protects them against predation (and probably makes it more likely that they'll be able to reproduce), but if I had to guess, I would say that it's not likely they are very long-lived, at least in general. However, your question prompted me to wonder -- do they live longer relative to other species of shrimp of the same size with less effective camouflage? Good question!

    :) Jackie

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