Friday, August 17, 2012


Ctenoimbricata (ten-oh-im-bri-kah-tuh) was an early echinoderm that looked a lot like a trilobite. It lived in the Cambrian, and the only two known specimens were found in Spain. It was described by researchers at the Natural History Museum of London and the University of Birmingham in 2012.

Ctenoimbricata was teardrop shaped, with many flat, triangular feeding appendages in the front. Like modern marine detritivores, it may have used its feeding appendages to put sand into its mouth, sort out the food from the sand, and spit out the excess sand. I think it probably would have eaten a small marine worm if it happened to catch one, like today's deep sea sea cucumbers do. 

Ctenoimbricata crawling on the sea floor

Ctenoimbricata was only 20 millimeters long, so it needed to have defenses. These were in the form of spines all over its body, similar to modern sea urchins. It was also probably slow, like modern echinoderms, and used tube feet to move around. It had hundreds, or maybe even thousands, of these tube feet, which are tiny, clear, gooey sticks, often with a suction cup-like device on the bottom used for moving around. 


Ctenoimbricata is a very important discovery because it is the oldest fossil that is definitely an echinoderm. The fossil was scanned and reconstructed, and the scientists found out it was bilaterally symmetrical, unlike other echinoderms, which have radial symmetry. This adds to the evidence that echinoderms and chordates may be related. 

Fossil of Ctenoimbricata

Thanks to Dr. Alien for first telling me about Ctenoimbricata!



  1. How do you pronounce that, Art? You ought to include a pronunciation guide with each entry. Keep up the good work!

    1. I fixed that for you. I'm pretty sure that's the way to pronounce it.

  2. many thanks for this post! it really explains well why Ctenoimbricata is so important!
    Samuel Zamora