Ready to settle down

  

Okay, back to these little snails that I posted on 27 January 2024!

This would have been a challenging one to identify unless you've spent some time looking at vermetid gastropods, or tube snails.  These are newly hatched Petaloconchus montereyensis!

And if you haven't heard of tube snails — yes, that's right, these are snails that don't crawl (at least as adults) and instead live in a calcareous tube that's cemented in place.  

This species of tube snail is a brooder — the adults lay egg capsules inside their tubes and the juveniles hatch and crawl away.  They only crawl for a brief time before attaching to the substrate — e.g., a rock surface or the tube of an adult.  (They tend to be gregarious.)

One of these snails settled after only two days.  In the video below you can see the tiny juvenile (only ~2 mm across) with the new tube that it produced.  And if you look very carefully you can see the coiled shell that it started out with at the very base of the tube!  So cool!  

As adults these snails are attached to the substrate, so they feed in a different way than many common marine snails.  Instead of grazing on algae on the rocks or in tidepools, Petaloconchus feeds by casting a mucous net into the water, letting organic material get caught in the net, then pulling the net back into its mouth.  The snail uses its radula (like a tongue with rows of sharp teeth) to retrieve the net.  Eric captured some video of that feeding motion, too, so he included it in this clip.  This is pretty spectacular footage of tube snails, so be sure to check it out!

The video sequence goes something like this:

• First 20 seconds — juveniles crawling on their own
• At ~22 seconds — juveniles exploring the outside of adult tube snails
  
• At ~48 seconds — close-ups of the newly settled juvenile with a coiled tube!
• At ~1:05 minutes — miscellaneous shots of adult tube snails with nice views of their radulas in action
  

Thanks for the terrific video, Eric!

Orange-rimmed

 

Scaled Tube Snail (Thylacodes squamigerus, formerly Serpulorbis squamigerus)

Although I first introduced tube snails (vermetid gastropods) several years ago, the individual shown above is a different species that I haven't yet shown on the blog.

Scaled Tube Snails are a more southern species — they're rare in Northern California.  I photographed the snail in the picture above in the rocky intertidal zone on 21 February 2016.  It was relatively small, so we're wondering if it's a younger animal, perhaps recently arrived with the warm water during the last couple of years.

Here's a different individual that I photographed on 9 April 2012:

 

Note the pretty orange band at the opening of the tube and the lack of an operculum (trap door).  The other species of tube snail in this area, Petaloconchus, is much smaller in size, lacks the scaly texture on its tube (see first photo above), and has an operculum. 

For an introduction to this fascinating groups of snails, review the post from 11 June 2012, and the video on 17 March 2015.