A Pack o’ Peanut Worms

photo: E. Loury

These little goobers are called peanut worms, or sipunculids.  Sipunculids are in their own phylum Sipuncula (that’s a pretty high level of taxonomic classification), so while their unsegmented bodies make them look like other marine worms (phylum Annelida), they are not directly related.

Sipunculids are pretty fascinating to watch because they can invert their long proboscis to bunch up (like the little peanut-look-alike on the far left), or extend it by essentially turning inside out.  These specimens were just some of the great diversity of critters I found poking around in a kelp holdfast.  Now the question remains: would you like those salted or unsalted?

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4 Responses to A Pack o’ Peanut Worms

  1. Danna Staaf says:

    Dawww, so cute! Just to provide altogether too much taxonomic information, because their affinities fascinate me: the fact that sipunculids are not segmented is what initially caused scientists to separate them from the segmented annelids. At some point, though, people thought they might just be a sub-group of annelids that had lost segmentation. The most recent thinking that I know about is that they’re probably more closely related to molluscs than to annelids (although molluscs and annelids are themselves closely related) but still definitely their own phylum.

    Yay worms!

  2. erinloury says:

    Thanks for the taxonomic tidbits, Danna! I was so thrilled to see your name printed in MULTIPLE locations while leafing through Light’s Manual recently while trying to pull together food web info for my thesis. :)

  3. Danna Staaf says:

    Aww, thanks! Huzzah for inverts!

  4. Danna Staaf says:

    Gahhh, my information was outdated! I just talked to Jim Watanabe and he reminded me that actually sipunculids are back in with the annelids these days. In fact, I think they’re considered to be a weird kind of polychaete (a subset of annelids). Yikes.

    It is weird though because they have no hint of segmentation, ever.

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