Micro Macro

  

During a beach walk yesterday (17 August 2024), Eric and I came across quite a few Giant Kelp (Macrocystis pyrifera) juveniles, including this very young individual (above) with a very small holdfast and one single blade. 

Most of these juvenile kelps were a little bit larger, but still early in their development.  Here's an example:

 

 

Below, two images show a closer view of the holdfast and the developing blades.  You can see the blades starting to split and the floats just starting to develop (as small swellings at the base of the blades):

 

 

 

 

 

I appreciated coming across these Giant Kelp juveniles and learning more about how they develop.

P.S.  I'm including one more photo just for fun.  The floats are little larger in this individual, and I hadn't noticed at the time, but you can see my reflection in the floats.  A self-portrait in kelp!

 

 

 

P.P.S.  Regarding the title of this post — In casual conversation, we sometimes shorten the scientific name of Giant Kelp, Macrocystis, to "Macro."  And because I am highlighting small individuals in this post, I thought it would be fun to play on those two names = Micro (small) Macro (Macrocystis).

Kelp toes

  

Tiny little kelp toes -- close-up of a Bull Kelp (Nereocystis luetkeana) holdfast attached to a rock.  Washed ashore in Bodega Bay on 27 July 2024.

A local network?

  

Net-of-Cords Kelp (Dictyoneurum californicum) 

Note the interesting reticulated or network-like patterning.  The blade was in the process of splitting into two through the center.

Dictyoneurum has a distinctive holdfast -- strap-shaped, with haptera (branching root-like structures) on both sides.

 

 

[This kelp had washed ashore, so I placed it on a rock to take a photo, but this kelp lives much lower in the intertidal zone.]

Holding fast?

 

 

We were doing surveys during the low tide this morning (27 April 2024) when Eric spotted this unusual interaction.  The holdfast of a small Sea Palm (Postelsia palmaeformis) had grown over and appeared to be attached to a chiton, Nuttallina californica!

 

Chitons are mobile grazers, moving over the surface of the rock and feeding on algae.  Perhaps they take breaks and stay in place for a while, which allowed the kelp to attach to it?

 

We didn't actually pull on the chiton to see if the haptera (root-like outgrowths) were definitely attached to the chiton, but it sure looks like it:

 

 

 

We'll be back in this area and can check on the kelp and chiton again to see how things turn out.

A bigger anchor

 

 

I was leading a walk about seaweeds today and we encountered a few of these Bull Kelp (Nereocystis luetkeana) holdfasts attached to small rocks.  The rocks likely served as anchors when the kelp was small, but once they grew larger these rocks just weren't heavy enough to keep the kelp in place.

 

 

 

Fun to see the little kelp "feet," but maybe next time the microscopic stage of the kelp will find a larger rock.  You know the famous quote, "You're gonna need a bigger boat anchor."  ;)

A chance meeting

  

Eric spotted this Bull Kelp (Nereocystis luetkeana) holdfast washed up on the beach recently.  The holdfast was still attached to a sizable piece of rock.  And it was interesting to see both Giant Barnacles (Balanus nubilus) — the large white barnacles in the center of the image — and pelagic gooseneck barnacles (Lepas sp.) — the small grayish clusters of barnacles along the left edge of the image.  

Giant Barnacles can be found in the low intertidal zone and subtidally, but pelagic barnacles are generally found offshore in the open ocean.  I'm not sure how often these two species of barnacles are found growing in the same place.  And seeing Lepas on this holdfast means the kelp and the rock it was attached to have been floating around offshore for a while before washing ashore.

Orange you glad?

About 5 years ago, I posted some photos of this distinctive nemertean, so some of you might remember Verrill's Ribbon Worm (Micrura verrilli).  We've only encountered this species a few times, so we were happy to see it again.

Today (4 May 2018) Eric noticed it inside a Giant Kelp (Macrocystis pyrifera) holdfast washed up on the beach.  I only had time to take a quick snapshot, but I thought it would be a worthwhile record to document.

For the older post and a little more information (and some nice photos), see "A colorful tip" from 16 March 2013.

Adrift and brooding

While looking at some kelp holdfasts a few days ago, Eric's sharp eyes noticed a dark red blob with some smaller blobs along the edges:

 

A Proliferating Anemone (Epiactis prolifera)!  We were excited about finding this species because although Proliferating Anemones used to be common in the intertidal zone on Bodega Head, they disappeared around 2011 (perhaps associated with a harmful algal bloom at that time).  It's been years since we've seen one on Bodega Head.

Proliferating Anemones are external brooders — the adults brood juveniles along a groove near the base of the column (where the anemones attach to the substrate, e.g., a rock or algae).  Because they don't have a planktonic stage (the juveniles simply crawl away from the adult), it might take a long time for this species to recolonize Bodega Head.  Their best chance might be via rafting on kelp.

Here's a close-up of the adult anemone shown above with two larger juveniles on its right side (the anemones expanded once submerged under water):

 

 

And below is another view of even smaller juveniles nestled in the "brood groove."  The larger tentacles of the adult are visible at the top left corner of the photo.

 

Juvenile anemones will spend ~4 months being brooded by the parent.  One study I read estimated that Epiactis might persist for ~100 days on a kelp raft.  If the kelp washes up in appropriate habitat (e.g., in the rocky intertidal zone), the anemones might have an opportunity to move off of the kelp and onto the rocks.  (Yes, anemones can move!)

On 14 October 2016, we encountered quite a few kelp holdfasts washed ashore, perhaps transported from southern locations, as discussed in last night's post.  Many of the kelps were covered with small pelagic barnacles (Lepas sp.), indicating they had been adrift for at least a little while.  Not only did Eric spot the brooding individual shown above, but he found two other smaller Proliferating Anemones — one pink and one green:

 

 

While on the boat trip on 9 October, I photographed a raft of drifting Bull Kelp:

 

Perhaps there were some Epiactis on this raft?  If so, I hope some of them make their way to Bodega Head.  It would be nice to have this anemone around again.

 

Colorful discs

Last night I mentioned we've been finding some kelp washed up on the beach.  Recently, one Bull Kelp specimen still had a relatively large holdfast at the bottom of the stipe, shown at the right in the photo below.  (A smaller kelp, Laminaria setchellii, was also attached to the Bull Kelp holdfast.)

 

Eric and I have been doing surveys of holdfasts for several years, so we took a closer look at this one.

Almost immediately, Eric noticed some very nice Daisy Brittle Stars (Ophiopholus kennerlyi) on and inside the holdfast.

Here are two close-up examples:

 

 

We kept looking, and it turns out there were more than 35 individual brittle stars on this holdfast (and we probably missed some).  We were especially fascinated by the diversity of color patterns on their central discs. 

So we took pictures of many of the individuals, and then Eric did something pretty special, just for you!

You can click on the photo below to see a slightly larger version (and to truly appreciate these spectacular brittle stars!).

 

In some ways, it's hard to believe this variety is seen in a single species.  Daisy Brittle Stars are known for amazing variation in the colors and patterns of their central discs (and their arms).

Moment (1962) seems to have been one of the first scientists to document this phenomenon in a related North Atlantic species, Ophiopholus aculeata:

"...out of hundreds of individuals collected at low tide in about an inch of water in a single cove on the coast of Maine it is not possible to find two exactly alike."

Here are examples of the patterns in Moment's brittle stars:

 

From Moment, G.B.  1962.  Reflexive selection: A possible answer to an old puzzle.  Science 136: 262-263.

Moment (1962) proposed a possible reason for the variation.  He called it "reflexive selection."  The basic idea is that variable color patterns make it harder for a visual predator (e.g., a fish) to develop a search image for one particular color variant...so predators impose selection for variation per se.  This process can generate something known as "massive color polymorphism" where just about every individual is unique.  According to Owen and Whiteley (1986), "The massive diversity thwarts the learning processes of the predators..."

Eric's fascinating collage is a wonderful demonstration of this individual variation.  Of the twenty shown, do you have a favorite color pattern...or, do you just like the diversity?

A shade of purple

 

Well, I couldn't help it.  This is another Moonglow Anemone (Anthopleura artemisia) from a Bull Kelp holdfast.  Although the color of this species is known to be variable, I hadn't seen one quite like this before and I just had to share it with you.  

How would you describe the color of the tentacles?  I'd call it a shade of purple.  And after searching around in my head, I eventually landed on aubergine.  What do you think?  Did you come up with a different color?

In some light, the oral disc of the anemone had beautiful blue reflections:

 

But in the end, it was the tentacles that really drew me in.  What an amazing color!

 

 

 

A mouthful for a Moonglow

 

This is just a fun record of an interesting prey item for a very pretty sea anemone.  Eric and I have continued our surveys of Bull Kelp holdfasts.  Recently, we found this beautiful Moonglow Anemone (Anthopleura artemisia) in a holdfast.  When we looked at it underwater, Eric noticed that it was holding on to some unusual food items!

 

It's important to remember that these holdfasts can be drifting around offshore for a while, so they can be substrate for pelagic species.

This Moonglow Anemone was eating cyprids (the final larval stage) of pelagic gooseneck barnacles (Lepas spp.).  It's probably an unusual food item for a Moonglow Anemone, as more often these anemones live on the bottom in intertidal or subtidal habitats where they're not likely to encounter pelagic barnacles.

Below is a closeup of the barnacle cyprids.  (If you'd like to see better pictures and learn more about this type of cyprid, review the post from 2 July 2012.)

 

And here's one more picture:  A closeup of the anemone's tentacles.  I'm guessing every tentacle has a different pattern!

 

The lion feeds tonight

 

Are you familiar with this animal?  The species name is "leonina," referring to a "lion" and the mane-like appearance of its oral hood and the peripheral tentacles.

Here's the entire animal viewed from below:

 

You can see that the oral hood is very large relative to the rest of the body.  Also visible is a long slender foot, and rounded, leaf-like cerata extending out to either side of the foot.

This is Melibe leonina, sometimes called the Lion Nudibranch or Hooded Nudibranch.

This nudibranch has some very unusual features.  Along with the impressive oral hood used to capture prey (such as small crustaceans), look for the interesting rhinophoral processes (flap-like or ear-like) and the small, grooved rhinophores at their tips — see images below.

 

 

Melibe inhabits kelp forests (especially Giant Kelp, Macrocystis pyrifera) and eelgrass beds (Zostera marina).  They are occasionally found in Bodega Harbor.

We were somewhat surprised to find two small Melibe in a Bull Kelp (Nereocystis luetkeana) holdfast washed up on Salmon Creek Beach on 13 August 2014.  

Here's a picture of the Bull Kelp holdfast.  I photographed it because there was also a small Five-ribbed Kelp (Costaria costata) attached to it, and I still have yet to find Five-ribbed Kelp growing on Bodega Head.

 

When we looked closely at the holdfast, Eric noticed an unusual brown blob.  This is what Melibe looked like on the holdfast, out of the water.  It's just below the tip of Eric's forceps:

 

 

It makes sense, but it made me smile to see this description from a paper written in 1923: 

"The body-substance of Melibe leonina appears as a mass of brown jelly, when the animal is alive or freshly caught..."  

Kudos to Eric for realizing this bit of "brown jelly" in the holdfast was worth looking at.  Who knew it would turn out to be a lion!

P.S.  The quote above is from Agersborgh, H.P. von Wold Kjerschow. 1923. The morphology of the nudibranchiate mollusk Melibe (syn. Chioraera) leonina (Gould). Q. J. Microsc. Sci. 67: 507-592.

eyePods?

Here's another discovery from the kelp holdfast last weekend.  Can you tell what's attached to the branches of the holdfast in the center of the photo below?

 

Because they would have dried up on the beach, we removed a few to take a closer look and to try to identify them.  Here's a small cluster in Eric's hand:

 

If you think you're seeing eyes, you are!  These are small fish eggs that were attached to the kelp.  Many of the tiny fish embryos appeared to be in the later stages of development — every now and then they would wriggle around inside of their clear, rounded capsules or pods.

Many details were visible under the microscope:

 

We're not sure what type of fish these are.  They appeared to be very long, with a dark checkerboard pattern running along the back.  

 

If you have experience identifying local fish eggs or fish embryos and have thoughts about what species of fish this might be, we'd be very interested in hearing about it!