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1

Sea urchins have long been among my favorite animals. From a purely aesthetic perspective I love them for their spiky exterior that hides a soft squishy interior. I also admire their uncanny and exasperating knack for getting into trouble despite the absence of a brain or centralized nervous system. Have you ever been outsmarted by an animal without a brain? I have. It's rather humbling.

Red sea urchins (Mesocentrotus franciscanus) and purple sea urchins (Strongylocentrotus purpuratus) share a common geographic range along the northeastern Pacific but generally live in different habitats. S. purpuratus is the common urchin in tidepools, while reds are almost always subtidal (although I have seen them in the intertidal on very low minus tides). The two species' habitats do overlap a bit, as the purple urchin can live in subtidal kelp forests alongside the reds. There is a commercial fishery for the gonads of red urchins, which are prized as uni by sushi aficionados. I've tried uni once, and it tasted exactly the way I imagined the gonads of a sea urchin would taste. Not a fan. I'd much rather make a different use of urchin gonads.

The other week I collected some urchins from the field, hoping that they'd have nice full gonads. Gametogenesis in many marine invertebrates, including sea urchins, is governed at least partly by annual light cycles. Provided they have sufficient food, purple urchins have ripe gonads and spawn in the winter, from December through March. Reds spawn in the spring, from March through June. In my experience the best time to induce spawning of purps in the lab is December or January, when the urchins have developed gonads but likely haven't spawned yet. There is no way of knowing the sex of any given urchin or the condition of its gonads, so this exercise is somewhat of a crap shoot even with the best of planning.

Ready to induce spawning!
30 December 2016
© Allison J. Gong

Today I shot up my eight field-collected purps, hoping to get at least one male and one female out of the deal. I got lucky with the timing, as one of the smallest urchins was a female and began spewing out eggs. This little female gave a lot of eggs! She was followed by three males and two more females. So out of my eight purps I ended up with three of each sex, and a spawning rate of 75% ain't bad.

I set up some mating crosses and fertilized all of the eggs. I divided the little female's eggs into two batches and fertilized them with the sperm of two different males (M1 and M2). Each of the other females' eggs was fertilized by M1, who gave huge amounts of sperm. When I checked on the eggs about two hours post-fertilization most of them had gone through the first cleavage division and seemed to be developing normally and on schedule.

2-cell embryos of Strongylocentrotus purpuratus
30 December 2016
© Allison J. Gong

Just for the hell of it I decided to shoot up some of the red urchins we have in the lab. I didn't really think they'd spawn, as it's not the season for them to be gravid. Red urchins are large, heavy animals with long and sharp spines and they are much more difficult to handle. Four of the five that I shot up did nothing, as expected. It took a long time, but just as I was about to give up on them the biggest red began dribbling out a couple thin streams of sperm. I examined the sperm under the microscope and they were very active and healthy. Fortunately I hadn't returned the purps to their tanks, and two of the female were still putting out some eggs. I rinsed the purp eggs into a clean beaker, pipetted up some of the red sperm, and added it to the eggs.

Sea urchin eggs are covered by a thick jelly coat. In the video you can see many of the red urchin sperm embedded in the jelly coat of the egg. Despite the frantic activity of the sperm, fertilization (as evidenced by the rising of the fertilization envelope off the surface of the egg) took much longer than it does when eggs and sperm come from the same species.

Egg of a purple sea urchin (Strongylocentrotus purpuratus) fertilized by sperm from a red urchin (Mesocentrotus franciscanus)
30 December 2016
© Allison J. Gong

Look at that beautiful zygote! Fertilization success in this hybrid cross was low, only about 50%. The eggs that did get fertilized went through the first cleavage division after about two hours later, which is right on time.

Eggs of a purple sea urchin (Strongylocentrotus purpuratus) fertilized by sperm from a red urchin (Mesocentrotus franciscanus)
30 December 2016
© Allison J. Gong

It remains to be seen whether or not the few hybrid embryos I have continue to develop. I have a colleague who has hybridized red and purple urchins successfully in the past, and has raised the offspring to adulthood. I don't have any expectations of great success with this little experiment, but it would be very informative to raise known hybrid urchins. I've seen animals in the field that look like hybrids and there's no reason to assume that hybridization between these two free-spawning species never occurs. The adults can be found living side-by-side subtidally, and there's enough overlap in their reproductive seasons that some individuals of each species could very well spawn at the same time. On the other hand, hybridization that can be forced in the lab doesn't necessarily occur in the field. I dumped a lot of red urchin sperm on those purple urchin eggs, and such high sperm concentration may overcome any mechanisms of reproductive isolation that exist under real-life conditions.

I'll know more when I check on things tomorrow.

1

I am fortunate to live in a place of great natural beauty. While the Pacific Ocean dominates much of the landscape, we are also partially surrounded by mountains. I grew up in the flatness of the San Joaquin Valley, a couple hours' drive from both the sea and the Sierra Nevada but not near enough for either to have any appreciable effect on daily life. When I first moved here from the Sacramento area to start graduate school, I felt claustrophobic because I had been used to looking out in any direction and being able to see for miles around. I've long since grown accustomed to the fact that the only miles-long vistas we get are over the ocean and have come to appreciate the proximity of the mountains.

Here we are ideally situated so that ocean and mountain forest are close enough that both can be explored in a single day. And in fact, I did just that the other day, on Boxing Day. The elephant seal (Mirounga angustirostris) breeding season has started, and I wanted to go up to Año Nuevo State Park to see them. Alas, this idea didn't occur to me soon enough to purchase tickets for the docent-led tour to the elephant seal reserve area, so we didn't get close to the seals. But it was a gorgeously clear day and the scenery was every bit as spectacular as you'd expect from this part of the coast.

Año Nuevo Island lies a short distance to the southwest off Año Nuevo Point and is reachable only by kayak. The island is a marine wildlife refuge closed to the public, uninhabited by any humans except scientists. Elephant seals, northern fur seals (a type of otariid, or eared seal), rhinoceros auklets, western gulls, and Brandt's cormorants all breed on the island. California sea lions don't breed on the island, but several thousand use it as a haul-out site throughout the year. During the elephant seal pupping season white sharks come to the waters around the island to feed on pups as they learn how to swim.

Año Nuevo Island, viewed from Cove Beach at Año Nuevo State Park.
26 December 2016
© Allison J. Gong

It is not common for the air to be so clear. Usually there is fog or haze that obscures the buildings. There used to be a lighthouse on the island; the dilapidated tower was pulled down in the early 2000s to safeguard the wildlife. Some of the other buildings--a 19th century residence and foghorn station--are currently used as research facilities.

View to the west from Cove Beach.
26 December 2016
© Allison J. Gong

Even without a ticket for docent-led tour of the elephant seal reserve area, you can hike to the staging area from where the tours depart. The trail passes a freshwater pond that is home to two endangered California herps: The red-legged frog (Rana draytonii) and the San Francisco garter snake (Thamnophis sirtalis tetrataenia). Years ago I had a colleague in graduate school who studied the elephant seals up at Año Nuevo. I went in the field with him one day and got to wear the special blue research windbreaker. He told me that before being allowed to drive into the reserve area all of the researchers have to take a driving test that involves not running over plastic snakes that are placed in the road. This is to make sure that the endangered snakes won't be inadvertently killed.

Freshwater pond at Año Nuevo State Park.
26 December 2016
© Allison J. Gong

We ate lunch at a lookout point of the tour staging area. Because the air was so clear we could see quite a way down the coast. Highway 1 as it passes under the cliffs immediately north of the Waddell Beach is visible at the far right edge of the photograph.

View towards Waddell Beach from Año Nuevo.
26 December 2016
© Allison J. Gong

After lunch we headed away from the coast and drove up Gazos Creek Road a few miles into the forest. It took all of about 15 minutes to go from beach to redwood forest. How cool is that? Two completely different ecosystems to explore easily within a day. Even the weather was different: sunny and warm at the beach, much cooler and damper among the trees.

Although we were up in the redwoods, this day I was fascinated by all of the moss growing on the trees. We've had a decent amount of rain so far, and the forests are satisfyingly wet and squishy. The creek we followed had washed out a bit of the road in a couple of places, and was closed to all traffic about 5 miles from the highway.

Moss-covered tree along Gazos Creek.
26 December 2016
© Allison J. Gong

We didn't have a lot of time to poke around in the forest, but since we were in the area we stopped at Rancho del Oso on our way home to visit my favorite tree. Rancho del Oso is at the bottom of Big Basin Redwoods State Park. I take my ecology students there for the first field trip of the semester, because there I can introduce them to two of the ecosystems that define the natural history of Santa Cruz.

My favorite tree is a coast live oak (Quercus agrifolia) that lives just off the trail at Rancho del Oso. I love its gnarled branches that grow horizontally at ground level. It is an old, wise tree. Looking through its branches you see into the redwood forest of Big Basin. I normally photograph this tree at a different angle, looking into the forest away from the trail. This day I decided to shoot it from an angle parallel to the trail. I don't think it's quite as dramatic from this angle but there's no denying the magnificence of the tree.

Coast live oak (Quercus agrifolia) at Rancho del Oso.
26 December 2016
© Allison J. Gong

Rancho del Oso is also the downhill terminus of the Skyline-to-the-Sea trail. The entire trail is about 30 miles, and most hikers take two or three days to hike the whole thing. I'm not much of a backpacker but one of the things I'd like to do this spring is the day hike from Big Basin down to Rancho del Oso. Doesn't that sound like great fun?

1

When the most recent epidemic of seastar wasting syndrome (SSWS) began back in 2013, the forcipulate stars were the first to succumb. This group includes conspicuous members of intertidal and subtidal habitats, such as:

  • Pisaster ochraceus -- the intertidal ochre star
  • Pisaster giganteus -- the giant spined star, which lives in the low intertidal and subtidal
  • Pycnopodia helianthoides -- the sunflower star, a huge monster of the low intertidal and subtidal.

In the past year or so, I've noticed P. ochraceus making a comeback at local intertidal sites. At first I was seeing stars in the 2-3 cm size range, and now I'm regularly seeing hand-sized ones clinging to the rocks.

4 mm juvenile Pisaster ochraceus star at Pescadero State Beach.
11 May 2016
© Allison J. Gong

You read that right. 4 mm in diameter. This is the tiniest forcipulate star that I've ever been able to ID in the field with any certainty.

Pair of Pisaster ochraceus stars in the low-mid intertidal at Natural Bridges.
22 July 2016
© Allison J. Gong
A hand-sized (dark orange) and much smaller (dark purple, tucked far back in the little cave) Pisaster ochraceus at Mitchell's Cove.
28 November 2016
© Allison J. Gong

It seems pretty clear that the ochre stars, at least, are making a comeback. It's likely that the larger ones are survivors of the SSWS plague. That little tiny one, though, may well be a post-SSWS recruit. Unfortunately we don't know how fast they grow once they recruit to the benthos. We do know that when they recruit they're about 500 µm in diameter, so even that little guy has grown a lot in however long it has been since it settled.

The really exciting news is that yesterday I saw my first P. giganteus since the SSWS outbreak began! I was up at Davenport Landing collecting sea urchins and saw this star in an urchin hole. The rock around here is a soft mudstone that is easily eroded. Urchins excavate holes by twisting their spines against the rock, and then live in them. Holes that are urchinless, for whatever reason, are quickly colonized by other organisms (including baby urchins).

A not-so-gigantic Pisaster giganteus star in an urchin hole at Davenport Landing.
13 December 2016
© Allison J. Gong

For a sense of size, this urchin hole is about 8 cm in diameter. The star is sharing it with a small anemone, most likely Anthopleura elegantissima.

Pisaster giganteus generally occurs lower in the intertidal than P. ochraceus, and I wouldn't expect to see it on a tide that isn't at least as low as -0.8 ft. It isn't as closely associated with mussel beds as P. ochraceus, either, because it lives lower in the intertidal. Fortunately, this week's low tide series includes a few days with tides below -1.0 ft, and I'm going back out today. I'll be keeping my eyes open for not only Pisaster stars, but also the Pycnopodia that disappeared a few years ago. Although Pycnopodia gets very large, I don't expect to see any really big ones running across the intertidal. However, Pycnopodia juveniles would indicate at least the beginning of a possible population recovery  from the SSWS plague.

So, wish me luck and keep your fingers crossed!

2

About three weeks ago I collected some mussels from the intertidal, to use both in the lab and in the classroom. A mussel can itself be an entire habitat for many other organisms. Many of the mussels I brought into the lab this last time were heavily encrusted with barnacles and anemones. I wanted to look more closely at one of the anemones so I took the mussel to the microscope. And, as often happens when I look at stuff under the microscope, I got totally distracted by things other than what I intended to.

But for the record, this is the anemone that started the whole chain of events:

A small aggregating anemone (Anthopleura elegantissima). 5 December 2016 © Allison J. Gong
A small aggregating anemone (Anthopleura elegantissima).
5 December 2016
© Allison J. Gong

Below the anemone there's a thick mat of small acorn barnacles (Balanus glandula) and a couple of leaf barnacles (Pollicipes polymerus). They were all alive when I brought the mussel into the lab, and over the weeks a few of them have died. But many of them are still kicking, both figuratively and literally.

Barnacles are most strange animals. Believe it or not, they are crustacean arthropods, somewhat closely related to crabs and lobsters. They live encased within a shelter of calcareous plates, which they can close seal up against predators and desiccation. I've never figured out why they are called "acorn barnacles," as they don't look anything like acorns to me, but in Balanus and such the base of the shelter is glued directly to a rock or some other hard surface. Leaf barnacles are shaped very differently, and have a fleshy stalk between the shelter that houses the main body of the animal and the rock surface.

Small acorn barnacles (Balanus glandula). 5 December 2016 © Allison J. Gong
Small acorn barnacles (Balanus glandula).
5 December 2016
© Allison J. Gong
Close-up view of a leaf barnacle (Pollicipes polymerus). 5 December 2016 © Allison J. Gong
Close-up view of a leaf barnacle (Pollicipes polymerus).
5 December 2016
© Allison J. Gong

To picture what's going on with a barnacle, imagine a shrimp lying on its back, then curl it up and stick the whole thing inside some calcareous plates. The thoracic appendages would be facing up. In barnacles the thoracic appendages are modified to be clawlike feeding structures called cirri. Barnacles are filter-feeders, collecting particles from the water by maneuvering the cirri in a sort of grasping fashion. So in a nutshell, or more precisely a test, a barnacle lies on its back and kicks its legs out to catch food.

Here's what B. glandula looks like when feeding. Note the clearly jointed cirri, with fine hairs that help catch particles. The cirri can be controlled independently, as you can see when they flick towards the center, and the entire apparatus can be rotated quite a bit.

Same deal with Pollicipes.

So that's the feeding part. A little strange, but not as interesting as the barnacles' sex lives. Let's start with some background about sexual function. And get your mind out of the gutter; this is real science stuff! Most of the animals that you're familiar with are described as dioecious (Gk: "two houses"). This means that female and male sexual functions are segregated; in other words, there are male bodies and female bodies. Other animals are described as monoecious (Gk: "one house"), so that a single body has both female and male sexual function. Monoecious animals could also be described as hermaphroditic. Some monoecious animals have male and female function in a single body at the same time; we call these simultaneous hermaphrodites. If a body first functions as one sex and then either acquires or switches to the other sex, we say the animal is a sequential hermaphrodite. Many fishes, including the California sheephead and the anemone fishes of coral reefs, are sequential hermaphrodites. Make sense?

Barnacles are simultaneous hermaphrodites. If you dissect an adult barnacle you will find mature ovaries and testes. This means that every barnacle can be both a mother and a father. The logical assumption is that monoecious animals should just fertilize their eggs with their own sperm. . . however, this generally isn't the case. The whole point of sexual reproduction is to combine the genomes of two individuals, and self-fertilization obviously doesn't accomplish this. So even though there are many hermaphroditic animals, very few of them are self-fertile.

One other weird thing about barnacles, and crustaceans in general, is their sperm. Arthropods have non-flagellated sperm, which means they don't swim (although some of them have amoeboid sperm that can ooze around a little bit). Many marine animals reproduce by broadcast spawning; that is, by throwing their gametes into the water, where fertilization takes place. Fertilization is facilitated by the sperms' ability to swim towards conspecific eggs.

Barnacles, with their non-swimming sperm, generally cannot rely on broadcast spawning to get sperm to egg. They must copulate. How do you suppose they do this? The same way that other animals (e.g., Homo sapiens) copulate, by using a penis or some other structure to transfer sperm from one individual to the body of another. In barnacles the penis's technical name is intromittent organ. The penis is inserted into the test of a neighboring barnacle and sperm is delivered. The receiving barnacle uses the sperm to fertilize its eggs. Unlike the cirri, the penis is unjointed and flexible, the better to seek out and slip into potential mates. You can see the intromittent organ unrolled and poking around.

Now think about the ramifications of these constraints. Barnacles live their entire post-larval lives permanently cemented to a rock. They also have non-motile sperm so sperm transfer can occur only by copulation. If the key to reproductive success is to mate with as many other individuals as possible, what do you suppose natural selection has done? That's right: barnacle anatomists, including the great Charles Darwin himself, have noticed that barnacles have incredibly long penises. In fact, compared to overall body size, barnacles have the longest penises in the animal kingdom, up to 15 times the length of the body! That's what you call bragging rights. Not all barnacle species are so amply endowed, however. The same leaf barnacle that I observed today (P. polymerus) has recently been reported to be a spermcaster; their penises are shorter than body length, and they release sperm that are captured by their downstream neighbors.

Wonders never cease.

Last week I finished my 30-day personal photography challenge, and I'm finally getting around to putting up a follow-up to this post. These are the photos from the second half of the challenge.

Day 16: Egret on the stack at Younger Lagoon. A high surf warning is in effect through today and the waves are BIG! This rock stack sits at the mouth of Younger Lagoon and gets bashed by waves 24/7/365. Usually on days like today I'll see pelicans and cormorants, true seabirds, hanging out on the stack and getting blasted by salt spray. Today a pair of snowy egrets (Egretta thula) landed on the stack but didn't stick around for more than a few seconds. As birds of wetlands and marshes, they didn't like it out there in these conditions.

Snowy egrets (Egretta thula) at the mouth of Younger Lagoon. 5 November 2016 © Allison J. Gong
5 November 2016
© Allison J. Gong

Day 17: Sunrise. I know, another sunrise. But this time, instead of the panoramic scale of brilliant colors I wanted to zoom in and capture the chiaroscuro effect of the backlit trees.

6 November 2016 © Allison J. Gong
6 November 2016
© Allison J. Gong

Day 18: This day showcased one of my favourite marine artefacts. This is the test, or internal skeleton, of the red sea urchin Mesocentrotus (formerly Strongylocentrotus) franciscanus. I took this photo with the 35mm lens.

7 November 2016 © Allison J. Gong
7 November 2016
© Allison J. Gong

Day 19: Pie makings. This is the first since I started this project that I've not been really happy with any of my photos. Maybe that's because I took a lot of shots of dead stuff at the marine lab this morning. However, this one does have a certain amount of visual interest, I think. As usual, the colors are spot on.

8 November 2016 © Allison J. Gong
8 November 2016
© Allison J. Gong

Day 20: Jade plant. Day 20 had me playing with depth of field again. I wanted to photograph something green, to remind myself of the resiliency of life. We somehow acquired this jade plant several years ago, and have dragged it with us from house to house. I think it has made three moves with us. I pretty much ignore it, and it had mostly died before last year's El Niño rains brought it back to life. And now it looks lush and green again! And may I just keep singing the praises of this 35mm lens? I feel it is making me a much better photographer.

9 November 2016 © Allison J. Gong
9 November 2016
© Allison J. Gong

Day 21: Diving grebe. A friend invited me to join her at the harbor for some "therapeutic docking". It took me about 10 minutes to remember that my concussed brain hurts when I lie with my head hanging over the edge of the dock. Oops. So I took pictures above water while my friend hunted for slugs. I really like this particular action shot of a grebe taking a dive from the surface. Bloop!

10 November 2016 © Allison J. Gong
10 November 2016
© Allison J. Gong

Day 22: Not a sunrise! Looks like another sunrise, doesn't it? But I took this yesterday at 17:00 so it isn't a sunrise even though the view is almost due east. So what is going on here?

11 November 2016 © Allison J. Gong
11 November 2016
© Allison J. Gong

Day 23: Super moon! I took on the super moon to practice some low light photography. I can see why photographers like those big telephoto lenses! My 18-140mm lens did a good job with details of the moon's surface, which was nice to see. Had to do some digital zooming to get this view.

13 November 2016 © Allison J. Gong
13 November 2016
© Allison J. Gong

Day 24: Lavender flower. This day saw me experimenting with bokeh. Before I started playing with this camera I didn't really appreciate the aesthetic potential of the non-subject material in a photograph. This study has really changed the way I look at the world. I feel that my artist's eye has developed quite a lot.

14 November 2016 © Allison J. Gong
14 November 2016
© Allison J. Gong

Day 25: Setting moon. Last night we were fogged in at sea level so we went uphill to get above the marine layer. From that experiment it's clear that I need more practice with night photography and long exposures. None of the pictures I took last night was very good in terms of technique, but one of them is aesthetically interesting and I may share it later. Anyway. This one is the super moon setting behind the trees this morning, at about the same time the sun was rising behind me.

15 November 2016 © Allison J. Gong
15 November 2016
© Allison J. Gong

Day 26: Gull in flight. I'm learning that photography is about the moment as much as the subject matter. In this case the subject is a western gull, a California Current endemic species, in flight. What do you think of the moment?

16 November 2016 © Allison J. Gong
16 November 2016
© Allison J. Gong

Day 27: Light through stained glass window. I went down to the church this afternoon to take pictures of the stained glass windows while the organ was getting fixed, then broken, then fixed again. I like the way the late afternoon sun shone through one of the south-facing windows and onto the opposite wall. I find the effect to be kind of spooky and not at all like the pictures I usually take. Maybe I need to play around more with angles as composition. The church dates back to 1864 (old by California standards!) and is the oldest church building still in use in Santa Cruz County. The gas lights, one fixture of which can be seen in the right-hand side of the photo, are part of the original architecture. The hanging electric lamp is not. We still use the gas lamps for evening services, and they are quite lovely when lit.

18 November 2016 © Allison J. Gong
18 November 2016
© Allison J. Gong

Day 28: San Juan Bautista. We went to San Bautista to meet family and friends for a birthday lunch and spent some time wandering around the mission grounds. This image captures the three elements of every California mission--the Indian supplicant, the cross, and the bell tower--and hints of the tension in these settlements. Like it or not, the missions are an important part of California history despite their record of enslavement of the people who lived here first.

19 November 2016 © Allison J. Gong
19 November 2016
© Allison J. Gong

Day 29: Chomp! This day was once again all about the moment. Lucie (calico) and Maggie (tortie) were napping together on the couch when Lucie woke up and started grooming Maggie. Usually it goes the other way around. This time Maggie put up with it for a long time before giving Lucie one warning chomp. After this they groomed each other for a while and then continued their nap for another couple of hours.

20 November 2016 © Allison J. Gong
20 November 2016
© Allison J. Gong

Day 30: Tiny mushrooms. I wanted the last entry to be something special so I waited until we went hiking at Big Basin Redwoods State Park for Green Friday. Hiking through the redwood forest we saw beauty all around us. And mushrooms everywhere! I was messing around with bokeh again and love how these little mushrooms look against the blurred background. My challenge is finished and I've learned a lot about my camera and taking pictures. Mission accomplished!

25 November 2016 © Allison J. Gong
25 November 2016
© Allison J. Gong

I feel that I've learned a lot during this challenge, both about my new camera and about photography in general. And I've developed a whole new appreciation for composition and especially for bokeh. I've completed the challenge, but intend to keep taking pictures as frequently as I can. I still have so much to learn!

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