Gold!

  

Well, I think Eric took home today's prize for the prettiest intertidal zone photo.  He found a beautiful cluster of kamptozoans (Barentsia conferta) living at the base of some coralline algae.  It's an amazing field photo of some tiny animals — each of the crowns (with the tentacles) in the photo above is only ~1 mm or less across. 

To learn a little more about kamptozoans, you can review these posts: "Tiny crowns" on 22 May 2020 and "Nodding heads" on 8 July 2012.

Nicely done, Eric!

Tiny crowns

Perhaps you didn't realize when you woke up today that you'd be seeing one of the best kamptozoan videos of all time!  ;)

Eric and I had to do some long-term surveys earlier this month and after finishing one of the surveys, Eric spotted this amazing clump of kamptozoans, also known as entoprocts.  Kamptozoans are an unusual group of animals (they're in their own phylum, so not really like any other invertebrates), and because they're so small, they're not often seen.

This colony of Barentsia conferta was growing in a tidepool at the base of some red algae and coralline algae:

 

You're seeing lots of individual zooids, each with a crown of tentacles attached to a calyx (the cup-like portion) on a stalk, that are connected together at the base.  [This species was first described by Kerstin Wasson in 1997.  She gave this kamptozoan the apt species name "conferta," which means "densely packed."]

 

Kamptozoans are sometimes called "nodding heads" because of the interesting motion within a colony.  And that's the best part of tonight's post.  Eric finally (it's been a long-time goal of his) captured some excellent video showing the zooids' mysterious nodding behavior (sometimes I think it looks a little more like knocking — it can happen pretty quickly, and they seem to influence each other).

Here's the video clip.  And I'm not kidding — this is probably one of the best kamptozoan videos available.  Enjoy!  [For a larger view, click on the "Enter full screen" icon in the lower right corner.  If you can't see the video player below, click on the title of this post to go directly to the web site.] 

Careening among the corals

Recently, while Eric was looking at the soft corals, he noticed some interesting animals living among them.  In the photo below, the tentacles of the soft corals are withdrawn, so the polyps look like small orange lumps.  Note the tall, thin, animals standing upright among the corals:

 

The tiny stalked animals are kamptozoans — a unique phylum formerly known as entoprocts, and commonly referred to as "nodding heads."  We think this is Barentsia parva.  It's the first time we've encountered this species. 

It's hard to tell from the microscope photos, but these animals are very small — only ~2 mm high.  (You can see why people don't encounter them very often!)

Here's an individual zooid (below).  Look for the following features:

- The stolon — the "runner" at the bottom from which the rest of the colonial animal arises (in this case, it looks golden and it's covered with debris)

- The calyx — the broad cup-like section at the top, with the feeding tentacles along the rim

- Rods — the long, narrow sections making up the stalk between the calyx and the stolon

- Nodes — the swollen sections at the base of the rod and sometimes in the middle of the rod

 

This illustration of Barentsia parva will also help orient you to their basic anatomy:

 

Modified from Wasson, K.  1997.  Systematic revision of colonial kamptozoans (entoprocts) of the Pacific coast of North America.  Zoological Journal of the Linnean Society 121: 1-63.

I mentioned that kamptozoans are commonly referred to as "nodding heads."  Luckily, Eric captured some of the "nodding" behavior that gives them this name.

In the video below, watch for the distinctive movements of individual zooids as they bend rather abruptly into their neighbors.  

Note that sometimes the feeding tentacles are extended upward; other times, they are withdrawn.  There's a sequence in the video between 29-35 seconds that shows particles moving in the water — the flow is being generated by beating cilia on the feeding tentacles.  If you look very closely, you might even see tiny particles that have been captured moving down the tentacles (from the tip down towards the mouth).  [If you can't see the video below, click on the title of the post above to go to the web page.]

barentsia parva sanford from Jackie Sones on Vimeo.

We hope you enjoyed this introduction to a seldom seen species.

P.S.  To compare Barentsia parva with a different kamptozoan, Barentsia conferta, review the post called "Nodding heads" from 8 July 2012.

Nodding heads

This is a colony of kamptozoans, also called entoprocts.  Kamptozoa means "bending animal."  They are commonly known as "nodding heads."  They're very small, only a few millimeters high, so most people haven't had a chance to get to know these delightful animals.

Entoprocts are in their own phylum.  They have a lovely crown of ciliated tentacles surrounding the mouth.  The cilia draw water up through the tentacles which aids in capturing food particles.  In the photo below you can see the cilia reflecting light.

 

All but one species of entoproct are marine.  On Bodega Head, we've encountered them on the rocky outer coast, but they're hard to find!  Eric discovered this colony growing in the low intertidal zone at the base of a red alga.

An individual in an entoproct colony is a called a zooid.  The three basic parts of a zooid include (1) the crown of tentacles, (2) the calyx (cup-like, holding most of the body organs), and (3) the slender stalk.

Here are two more views of a zooid, one from the side and another from above.

 

 

Entoprocts reproduce both sexually and asexually.  They can bud new individuals along creeping stolons (or runners) — see below.

 

In the photo above, note that each zooid has a swollen node at the base.  We think this character helps identify this species as Barentsia conferta.  (The species name, conferta, means densely packed.)

Here's another view of a small portion of a colony.  Note the blurred movement of one zooid at center left.

 

Entoprocts are called nodding heads because of their very curious and distinctive way of moving.  Libbie Hyman (1951) described it as "odd flicking, bowing movements."  Suddenly, one individual will bend over quite dramatically.  This movement then cascades through the surrounding individuals.  It's somewhat like bumper cars. 

A still photo doesn't capture this behavior, so for your viewing enjoyment and an introduction to nodding heads, check out this short video clip we made!  (Best viewed at small size for now.)

entoprocts from Jackie Sones on Vimeo.