Blue Christmas?

  

Well, the waves were on the larger side today (10-12 foot west swell), but we picked a safe spot and went out for a little holiday tidepooling in the mid intertidal zone late in the day.  One of my favorite observations was this beautiful blue shrimp!  I'm not sure which species this is, but I couldn't resist sharing the photo.  [You can click on the image for a larger version.]

Feasting on crab

  

There have been lots of folks fishing for crab off Bodega Head this week.

 

 

 

Once caught, it's important to handle your crab carefully.

 

 

 

 

And then it's time to enjoy it!

 

P.S.  Eric and I are sending warm wishes your way for a day with moments of gratitude.  Perhaps it will include a little time outside giving thanks to our wild neighbors?  And many thanks for tuning in to the Natural History of Bodega Head.  I so appreciate your company on this journey to learn about the natural world around us!

Find the shrimp?

  

Can you find the shrimp?

More info tomorrow night!

Bright blue highlights

  

Eric had good luck with spotting interesting shrimp last night (25 November 2022).  Here's another one -- with red/maroon background colors and bright blue spots scattered across the abdominal segments.  We think this is probably a Heptacarpus species, but I'm not sure which one.

And here's an even closer view of those beautiful blue spots!

 

 

Fun to know these handsome shrimp are living along the Sonoma coast!

Blue galaxy

 

 

So cool!  Eric photographed this shrimp in the low intertidal zone tonight (25 November 2022).  We think it might be a species of Heptacarpus, possibly Heptacarpus brevirostris.  (But if you have more experience with shrimp and have a different opinion, please let us know.)

 

I love the blue-green background color and the bright blue spots!  Sometimes Heptacarpus brevirostris is called the Stout Coastal Shrimp, but this one made me think of a galaxy, so tonight I'm calling it the Blue Galaxy Shrimp.  :)

 

Thanks, Eric!

Visiting the cleaners

  

Looking around in the low intertidal zone in Monterey County this week, I peeked over a rock to see these striking striped shrimp.  Beautiful!

I kept scanning and found a handful of these shrimp in a tidepool.  This was my first view (below).  [Don't miss the smaller individual at the bottom.]

 

 

I'm not as familiar with many invertebrates that are more common in Southern California, but Eric helped me identify these as Red Rock Shrimp (Lysmata californica).  Typically they are found south of Point Conception, but there are recent records of them from San Luis Obispo, Monterey, Santa Cruz, and Pillar Point (between 2015-2021).  And there is an older record from Coos Bay, OR, from 1983 after a significant El Niño event.

These are fairly large shrimp — the largest individual I saw was ~7 cm (~3 inches) long.  They have a grayish translucent background color and bold red striping.  Another notable feature is the extremely long antennae.

 

 

An intriguing aspect of Red Rock Shrimp — they're cleaner shrimp!  Which means that they are often found in large aggregations and are known to have a mutualistic relationship with various fish and invertebrates that involves "cleaning" — the shrimp remove parasites and other material from their "clients" including moray eels, Garibaldi, and spiny lobster.

 

 

 

Most of the other species in this genus of cleaner shrimp (Lysmata spp.) are tropical.  I'm not sure how common Red Rock Shrimp are north of Point Conception right now, but if you happen to see one north of Santa Barbara it would be worth reporting your observation.  

Two more images for the record:

 

 

 

 

 

I felt fortunate to catch a glimpse of these beautiful shrimp and couldn't help wondering which animals might be stopping by next to visit the cleaners.

Nibbling

  

I was helping Emma and Fern scout some potential research sites this afternoon (9 July 2022) and we started to notice some Western Tussock Moth caterpillars (Orgyia vetusta) in the high intertidal zone.  Eventually we discovered that the caterpillars were coming from the top of the bluff where they had been feeding on lupines.  At one point Fern looked down to see the scene shown above — a Lined Shore Crab (Pachygrapsus crassipes) feeding on one of the caterpillars!  I haven't seen this before, so it seemed worth documenting.

Earlier in the day I had noticed a few of these caterpillars, but in this case what caught my eye is that the caterpillars were eating seaweed!  Here's a Western Tussock Moth caterpillar nibbling on Ulva intestinalis:

 

 

P.S.  With thanks to Fern and Emma for sharing their observations today!

Dashing

  

Juvenile Hairy Rock Crab (Romaleon jordani, formerly Cancer jordani) with a fun color pattern.  Thanks to Eric for spotting it!

Christmas decoration

  

 

Since many folks are decorating at this time of year, we thought you might enjoy seeing this local decorator crab.  Meet the Cryptic Kelp Crab (Pugettia richii)!  They're known as decorator crabs because they add pieces of seaweed to their rostrum (nose) and carapace (back) for camouflage.  In the photo above, the narrow red-brown seaweed and the green leafy seaweed are attached to the back of the crab.

 

If you look closely on the backs of the crabs, you can even see the specialized hooks for holding seaweed.  Below, look for the clusters of narrow curved hooks near the base of the seaweed.  The crab pushed the seaweed under these hooks to hold it in place.  The better to hide from fish and octopus!

 

 

 

Happy Holidays to all!

Spring cleaning

If you've looked closely at a porcelain crab, you've probably noticed that it has a large pair of claws and three pairs of striped walking legs.  The photo below shows the Chocolate Porcelain Crab (Petrolisthes manimaculis).  They're found under cobbles and boulders in the rocky intertidal zone. 

  

It's easy to overlook that porcelain crabs also have a 5^th pair of limbs that are greatly reduced in size relative to the walking legs.  Porcelain crabs along with some other types of crabs (such as hermit crabs, mole crabs, and pelagic red crabs) belong to a taxonomic group called the Anomura.  Unlike Cancer crabs, kelp crabs, and other “true crabs,” anomuran crabs never use their last (or 5^th) pair of limbs for walking.  In the drawing below, the 5^th pair of limbs are marked with red arrows:    

 

Modified from Fleischer, J., M. Grell, J.T. Hoeg, and J. Olesen. 1992. Morphology of grooming limbs in species of Petrolisthes and Pachycheles (Crustacea: Decapoda: Anomura: Porcellanidae): a scanning electron microscopy study. Marine Biology 113: 425-435.

These appendages are small enough that they are easy to miss.  The close-up photo below shows this 5^th pair of limbs marked with black arrows:

 

Given the small size of these appendages, one might wonder if they are vestigial structures that no longer serve a useful function?

Well, it turns out that in porcelain crabs, these appendages are actually important for grooming.  The slender grooming limbs can be folded up like a jackknife when not in use, but they are remarkably long and flexible when extended.  As you can see in Siena’s drawing below, the grooming limbs end in a claw.  They are also covered with several types of bristles (or setae).

 

Drawing by Siena Watson.  Modified from Fleischer et al. 1992.

The grooming limbs are used both to clean the gills within internal chambers and to clean the external surface of the crab of detritus, debris, parasites, and other attached organisms.  The bristles act as cleaning brushes, whereas the toothed claw is well equipped to remove objects that are more firmly attached.  Some of the bristles on the claw are sensory structures that appear to allow the crab to both feel and taste the objects that are encountered during grooming.

Eric captured some nice video of the grooming limb of a porcelain crab in action.  Porcelain crabs are suspension feeders.  Near the beginning of the video you will see the crab sweeping its specialized fans through the water to capture food.  Then the crab starts using one of its grooming limbs (white arrow at ~15 seconds) to vigorously scrub around its back, eyestalks, and long red antenna!  It is amazing to see the flexibility and dexterity of the limb as it diligently cleans and grooms.

Porcelain crab grooming from Jackie Sones on Vimeo.

[Apologies for not posting more this week.  I'm recovering from surgery on Monday, and my ability to stay upright is more limited than I had hoped.  I'm feeling better now though, and I hope to resume more frequent postings in the near future.  For now, Eric offered to help put together the information for a really fun post.  Many thanks to Eric and Siena!]

 

Pelagic Red Crab zoea!

Okay, here we go — the answer to last night's mystery photo.  As a reminder, here's the image:

 

We received several correct guesses.  This is the zoea (free-swimming larval stage) of a Pelagic Red Crab (Pleuroncodes planipes)!  The photo below shows the entire zoea:

 

We haven't been able to find many pictures of Pelagic Red Crab larvae, so we thought it would be fun to share a few.  Eric also recorded some video (see below)!

Here's the basic sequence of events:

After finding live Pelagic Red Crabs on 24 January 2017, I was measuring them and counting the number of males and females.  I discovered that several of the females were carrying eggs.  Similar to lobsters, they brood their eggs attached to the underside of the abdomen (see below):

 

We wondered if the embryos would develop in Northern California waters.  Based on a previous study that found they did well at 12°C, it seemed like they should develop and hatch in ~22 days.

Right on schedule, the embryos hatched today (after a minimum of 22 days)!  This is what we saw when we came into the lab this morning — an adult female surrounded by hundreds of larvae, each ~2 mm long:

 

And here's a close-up of some of the larvae in the jar:

 

Carl Boyd described the larval stages of Pelagic Red Crabs in 1960.  This drawing shows the first zoea:

 

Modified from Boyd, C.M.  1960.  The larval stages of Pleuroncodes planipes Stimpson (Crustacea, Decapoda, Galatheidae).  Biological Bulletin 118: 17-30.

And here's a close-up of a zoea in a similar position (shown in dorsal view, from above):

 

As mentioned, Eric took advantage of a rare opportunity to film some live Pelagic Red Crab larvae.  You'll see the very active newly-hatched zoeae zipping around.  (Among the swimming sequences and close-ups, watch for the rapidly beating heart.)  Note: If you receive this via e-mail and can't see the video file below, click on the title of the post above to go directly to the web site.

pelagic_red_crab_zoea_sanford from Jackie Sones on Vimeo.

 

I can't help showing a couple more pictures — two extreme close-ups.  Check out the beautiful telson (last abdominal segment or "tail")...

 

...and the wonderful second antenna (the outermost antenna, adjacent to the eye):

 

We feel very fortunate to have observed and photographed these fascinating larvae.  We hope you enjoy them, too!

Little fighter

We were doing a beach survey...I passed an old, eroded kelp holdfast...but Eric picked it up and looked more carefully.  His sharp eyes noticed something with spots, and when viewed up-close, he recognized it as a tiny crab, only ~4-5 mm across:

 

There were thin white rings surrounding each dark spot and smaller orange speckles scattered across the carapace:

 

Eventually I noticed the dark tips on the claws — an important clue to the identification of this crab!

 

Seeing the dark claws made us realize this was probably a juvenile black-clawed crab (Lophopanopeus sp.).

And then we learned about another important feature to look for when identifying this group of crabs: hairs on the different segments of the walking legs:

 

Unfortunately, I don't have experience evaluating this character, and I might need better pictures, so we'll have to request help from crab experts to see if we can figure out which species of black-clawed crab this is.

P.S.  The scientific name was intriguing to me.  I tried to interpret the meaning behind it.  "Lopho" means tufted or crested, and "panopeus" could refer to a character in Greek mythology known to be a fighter. This is guesswork, but perhaps "Lopho" refers to the hairs mentioned above, and perhaps "panopeus" refers to the strength and behavior of these crabs?  For crabs of the same weight, the crushing force of the claw of a black-clawed crab is known to be more than 5x greater than a shore crab (Hemigrapsus nudus) and 2x greater than a rock crab (Cancer productus)!  Watch your fingers!