Peanut brittle?

  

Okay, I know I've shown a few peanut worms recently, but this was a nice view of several different peanut worms (Phascolosoma agassizii) extending their introverts from a crevice and using the short ring of tentacles at the end to feed.  You can also see several arms of a brittle star extending out of the crevice and even lying across one of the peanut worms.

P.S.  If you want to play the "phyla game" again, look around to see what you can find.  Below I'll list the phyla in this image.

1. Peanut worm (Phascolosoma agassizii), Phylum Sipuncula
2. Brittle star, Phylum Echinodermata
3. Barnacle, Phylum Arthropoda
4. Limpet (checkered, in lower left corner), Phylum Mollusca
5. Tube worm (orange tentacles, upper right corner), Phylum Annelida
6. Flatworm (gray/white, same species as last night), Phylum Platyhelminthes

Local diversity

  

Eric noticed a beautiful scene in the low intertidal zone a few days ago.  There are six (!) different phyla (major animal groups) represented in this image, all in an area that was only ~4 cm x 4 cm (or ~1.5" x 1.5").  

Feel free to look around and see what you can find.

In the next image, I've circled or pointed to representatives of each phylum.

 

 

Green arrow = sea anemone (Epiactis handi), Phylum Cnidaria
White circle = barnacle (Chthamalus dalli), Phylum Arthropoda
Blue circles = flatworms (unidentified), Phylum Platyhelminthes
Orange arrow = peanut worm (Themiste pyroides), Phylum Sipuncula
Purple oval = tubeworm tentacles (Phragmatopoma californica), Phylum Annelida
Pink arrow = chiton (Tonicella lokii), Phylum Mollusca

Golden spirals

  

Another in the tubeworm series — this one with beautiful golden stripes and blue tips!  Spirobranchus spinosus photographed in the Carmel area on 26 February 2021.

P.S.  Refer to first post called "Magic blue spiral" on 27 February 2021.

Magic blue spiral

  

We were long overdue on a survey that we needed to get done in Monterey County, so we made a quick day-trip down to the Carmel area this week.  Thankfully, we were able to finish the survey in a few hours, and at the very end of it Eric spotted this beautiful tube worm in a tidepool.  Although time was short, he managed to take this wonderful photo.  Meet Spirobranchus spinosus!  This is a more southern species, but we'll be on the lookout to see if any show up in Bodega Bay in the future.

Isn't the blue color amazing?  The tentacles of this species aren't always blue, and I hope to show some of the color variation in another post.

Spiralling in

 

A beautiful tubeworm, Spirobranchus spinosus, photographed in the low intertidal zone in Monterey County on 31 August 2019.

 

Turquoise

 

I'm not 100% sure what species of worm this is, but isn't the color amazing?  This beautiful turquoise polychaete — possibly Nereis grubei — was crawling over the rocks in the intertidal zone.  It was photographed on Bodega Head on 16 May 2017.

Banded tentacles

 

A beautiful feather duster worm, Parasabella media, in a rocky shore tidepool.  The tentacles (called radioles) are used to capture suspended food particles from the water and in respiration.  Photographed in northern Sonoma County on 24 February 2017.

Rings around the boulders

We were on our way to do field work in the rocky intertidal zone early this morning, when we noticed this:

 

Can you see the orange coloration along the lower part of the wall and forming rings around the boulders?

Here's a closer view (below).  The boulder is about 2.5 feet across (~76 cm).  Any guess about what's causing the orange color?

 

There are orange sponges in this area that could look like this from a distance, but it didn't seem quite right, so we got down for an even closer view:

 

Spirorbid tubeworms!  Wow, neither of us had seen such dense and expansive aggregations before.  

The next photo is helpful because some of the tubeworms are underwater with their bright orange tentacles expanded, and others are out of the water with their tentacles withdrawn so it's easier to see their white tubes (with just a hint of orange at the entrance).

 

Most spirorbid tubeworms are brooders (brooding their larvae) and once released their larvae have very short planktonic durations — swimming in the water column for a very short time before they settle onto a rock (or other suitable surface).  

Perhaps the surge channel we walked by is a good setting for high retention, where many larvae are released and then settle in close proximity to each other instead of being swept away by waves and currents?

If you're interested in seeing microscope views of these fascinating tubeworms, review the post from 6 February 2012.

Suckers for the low zone

This might be tough, but do you want to guess what type of animal this is?  This is a close-up view of one end of the animal:

 

If you think that looks like a sucker, you're right!  It's a magnified view of a caudal sucker (the tail end).

Here's a look at the other end:

 

If you think that looks like a sucker, you're right again!  ;)  It's a magnified view of an oral sucker (the mouth end). 

I'll also tell you that this is a marine invertebrate.  So you need to visualize an animal with suckers at both ends...

Are you ready for the answer?

The next photo will reveal the entire animal after Eric discovered it attached to a rock in the low intertidal zone:

 

If you think that looks like a leech, you're right!  This is Trachelobdella oregonensis.   It was ~30 mm long when outstretched.

The diagram below highlights some of the main features of this species.  Look for (1) overall dark coloration; (2) the pale caudal sucker; (3) the small oral sucker with lighter patterning; and (4) 10 pairs of "pulsatile vesicles" = the bumps along the sides.

 

Modified from The Light and Smith Manual (edited by James Carlton) 

And here's a view of the leech while it was attached to the side of a bowl by its caudal sucker.

 

Although this individual was not attached to a fish, Trachelobdella oregonensis is known to be a parasite on a specific fish host — Cabezon (Scorpanichthys marmoratus).

The Light and Smith Manual states that this species has only been found from the central Oregon coast.  However, I searched the Smithsonian's invertebrate collection, and two California locations are represented: Crescent City and Pacific Grove.  So this record from 26 November 2015 could be a first for the Bodega Bay area.  [Yes, we found this leech on Thanksgiving (after our holiday meal) — there are so many interesting things to discover in the low intertidal zone that we couldn't resist a short field trip during one of the better low tides of the year!]

One more quick fact: Of ~700 species of leeches worldwide, only ~100 of those are marine.