Leaving the lair

  

Okay, have you been wondering about the Turquoise Dragon and her developing larvae?  (See posts on 24 July 2023 and 29 July 2023.)

The larvae hatched on 2 August 2023 and Eric caught some of them crawling and swimming away in the video clip below.

The epitoke (reproductive stage of the worm) brooded the embryos/larvae for at least 12 days.  It's likely that the larvae will spend some time swimming in the plankton and growing (adding more body segments) before settling to the bottom and metamorphosing into juvenile worms.

[If you can't see the video player in your e-mail, click on the title of this post above to directly to the NBHB website.]

Thanks to Eric for sharing this great video clip!

Turquoise dragon!

 

Last week, Eric’s summer class collected plankton tows in Bodega Bay and examined them under the microscope.  One of the students (Pachia) spotted this very striking polychaete worm that was turquoise in color and carrying a mass of bright orange eggs!    

 

The worm was quite small (only ~2.5 mm long).  Those are millimeter marks on the ruler below:  

 

 

 

This worm is known as an epitoke, a type of reproductive individual that occurs in some species of polychaetes.  Epitokes swim up from the bottom to the surface where mass spawning events occur.  In most cases, both male and female epitokes free-spawn their gametes into the water where fertilization occurs.   

 

However, the species shown here is unusual in that females do not free-spawn, but instead hold onto an egg mass and protect their fertilized embryos for some time while they develop.  Although we aren’t able to identify the species, this worm is likely a member a member of a particular group of polychaetes (Family Syllidae, Subfamily Autolytinae). 

Luckily, Eric was able to capture some video of this beautiful worm, whose appearance reminds us of a tiny turquoise dragon.  [If you can't see the video player in your e-mail, click on the title of the post to go directly to the NHBH website to watch the video.]

 

With many thanks to Pachia for spotting this wonderful worm, to Bruno and Richard for helping with the identification, and to Eric for putting together the story with photos and video.

The things she carries

Check it out!  When sorting through some low intertidal samples looking for ribbon worms, Maddy spotted this tiny polychaete worm.  It was only ~2 mm long, and it was brooding embryos along its back!

For orientation, look for the red eyes at the anterior end.

Before this, we hadn't known that some marine worms use this life history strategy.  (It reminded me of the frogs that brood embryos on their backs.)  The embryos undergo direct development, i.e., they'll continue to develop on their mother's back until they're tiny juvenile worms.

Meet Salvatoria sp.!

 

Many thanks to Maddy for spotting this fascinating worm, to Eric for taking photos, and to Leslie for help with the identification.

At home in the hydrocoral

The Hydrocoral Chronicles continue!

While looking for Polydora on the surface of the hydrocoral Stylantheca papillosa, Eric noticed a small raised blister (~3 mm long) with an opening at one end.  The antennae of a tiny worm were barely visible in the darkened doorway.  [I think the little blister is reminiscent of a pink igloo!  :) ]

 

We were curious about this worm, and eventually found a reference to a little-known syllid polychaete, Proceraea penetrans, first discovered living on the subtidal hydrocoral Stylaster californicus in southern California (Wright and Woodwick 1977).

In response to the worm, the hydrocoral creates a "blister" that serves as a home for the worm.  Eric was able to coax this worm out of its home for a closer look and it turns out that it was indeed Proceraea penetrans!  Many thanks to Leslie Harris for confirming this identification.

This appears to be the first record of Proceraea penetrans living on the intertidal hydrocoral Stylantheca papillosa, and also the first record of this species north of the Channel Islands. 

Note that Proceraea penetrans is tiny (see photos below).  [Its small size is likely one of the reasons it has been observed so rarely.]  We don't believe any photographs of a live specimen have been published before.  With this post, you get to see photos and a video!

The entire individual was only ~5 mm long:

 

Here's a magnified view of the anterior end, with 2 pairs of red eyes:

 

Another fascinating aspect of Proceraea penetrans is its life history.  Some polychaete worms, including this species, produce reproductive individuals called epitokes.  Epitokes are specialized for swimming to the surface of the ocean, often in response to lunar cues, where they release eggs or sperm with other epitokes during mass spawning events. 

To facilitate this journey, epitokes often have enlarged eyes and modified setae (bristles) on their appendages that aid in swimming.  In some species the entire adult worm transforms into an epitoke.  But in other species, including Proceraea penetrans, the adult worm produces epitokes asexually, as genetically-identical buds attached at its posterior end (see photos below).

When the lunar cues are right, the mature epitoke separates from the posterior end and takes a one-way journey to the surface to spawn while the adult worm (formally called an atoke) remains safe and sound on the bottom.  Proceraea penetrans produces just a single epitoke at a time. 

Below, here are two views of the epitoke.  In the first, note the adult worm (the atoke) in the lead, and the epitoke developing at the posterior end of the atoke.  Look for one set of eyes at the head end of the atoke (bottom of photo), and a second set of eyes at the head end of the epitoke (top of photo).

 

It looks odd to see eyes in what appears to be the mid-section of the worm.  Remember that the portion in front is the benthic adult and the second set of eyes belongs to the reproductive epitoke that will separate and swim to the surface to spawn.

 

Eric was lucky to capture a short video clip (probably the first ever of this species).  Note that the epitoke is longer than the atoke — watch how long it takes for the epitoke to pass through the view!

Proceraea penetrans from Jackie Sones on Vimeo.

Amazingly, some closely-related syllid polychaetes in the same family (Autolytinae) as Proceraea produce a chain of multiple epitokes at one time.  The photo below of Myrianida pachycera from the Indo-Pacific (and introduced to Southern California) is a particularly beautiful species and a striking example of this phenomenon.  Thanks to Leslie Harris for sharing her wonderful photo.