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In recent years, citizen science has become a very important provider of biological data. This movement relies on the participation of people who have an interest in science but may not themselves be scientists. There is some training involved, as data must be collected in consistent ways if they are to be useful, but generally no scientific expertise is required. The beauty of citizen science is that it allows scientists and science educators to share the experience of discovery with people who might not otherwise know what it's like to really examine the world around them. I think it is a great step towards creating a less science-phobic society, one in which science informs policy on scientific matters.

LiMPETS stands for "Long-term Monitoring Program and Experiential Training for Students." The program seeks both to give students experience doing real science and to establish baseline and long-term ecological data for California's sandy shores and rocky intertidal areas. As an intertidal ecologist myself, I naturally wanted my students to participate in the rocky intertidal monitoring.

The LiMPETS coordinator for Santa Cruz and Monterey Counties is a woman named Emily Gottlieb. She and I decided to have my class monitor the site at Davenport Landing. Emily came to class two weeks ago to train the students in identifying the relevant organisms and recording the data.

Practice tidepooling, training for real-life monitoring in the intertidal. 15 April 2016 © Allison J. Gong
Practice tidepooling, training for real-life monitoring in the intertidal.
15 April 2016
© Allison J. Gong

Tidepooling is easy and comfortable when you do it inside a classroom seated at a table. But today was all about the real thing. It was overcast and breezy when we met up with Emily at 09:30 and headed out to the site. At first the students seemed to be a little skeptical about the whole thing.

Students get their first look at their morning workplace. 29 April 2016 © Allison J. Gong
Students get their first look at their morning workplace.
29 April 2016
© Allison J. Gong

We were extremely fortunate to be joined this morning by Dr. John Pearse, Professor Emeritus of Biology at UC Santa Cruz, one of my graduate advisors, and the founder of LiMPETS. Dr. Pearse has been monitoring some sites, including this one at Davenport Landing, since the 1970s. He is THE person to talk to about intertidal changes in California over the past 40 years.

Years ago John set up permanent transect lines and plots at Davenport Landing, marking the origin of each transect with a bolt. The first thing we had to do when we got to the site was find the bolt. Then John ran out the transect line to the lowest point that students could work safely, given the conditions of tide and swell; this happened to be about 15 meters.

Dr. John Pearse runs out the vertical transect line. 29 April 2016 © Allison J. Gong
Dr. John Pearse runs out the vertical transect line.
29 April 2016
© Allison J. Gong

For the vertical transect, 1/2-meter square quadrats were placed at each meter. Some organisms were counted as individuals and others were marked as either present or absent in each of the 25 small squares within each quadrat. Emily gave the students their assignments and data sheets, and they spread out along the transect line.

Students working the vertical transect. 29 April 2016 © Allison J. Gong
Students working the vertical transect.
29 April 2016
© Allison J. Gong
LiMPETS sampling 29 April 2016 © Allison J. Gong
LiMPETS sampling
29 April 2016
© Allison J. Gong
LiMPETS sampling 29 April 2016 © Allison J. Gong
LiMPETS sampling
29 April 2016
© Allison J. Gong
LiMPETS sampling 29 April 2016 © Allison J. Gong
LiMPETS sampling
29 April 2016
© Allison J. Gong

Aside from the experience of learning how to do this kind of data collection, I hope the students understand what a privilege it is to have been in the field with John Pearse. He has such a thorough understanding of the intertidal that he is a treasure vault of knowledge. Here he is explaining what owl limpets are all about:

Dr. John Pearse explains what owl limpets are and how to find them. 29 April 2016 © Allison J. Gong
Dr. John Pearse explains what owl limpets are and how to find them.
29 April 2016
© Allison J. Gong

Interestingly, we didn't find many owl limpets. And certainly not any of the big ones that I see all the time at Natural Bridges. John said that this is one of the differences between a protected area (Natural Bridges) and an unprotected one (Davenport Landing). Collecting is not allowed at Natural Bridges, and the owl limpets are left unmolested--by humans, at least--to grow large (10+ cm long is not uncommon). On the other hand, people do collect at Davenport and I've heard it said that owl limpets are good to eat; today we saw fewer than a dozen owl limpets and they were all small, none larger than 3 cm long.

The sun came out after a while, but the wind also picked up. The tide came up as well, and some of the students got more than a little wet. Overall they were real troopers, though, and I didn't hear much complaining. Next week is the last lab of the semester, and we'll be participating in another citizen science project. But that's a tale for another day.

I did take advantage of the beautiful setting to have one of Emily's LiMPETS volunteers (and a former student of mine!) take our class photo. Here we are, the Bio 11C class of 2016!

Class photo, taken at Davenport Landing. 29 April 2016 © Allison J. Gong
Class photo, taken at Davenport Landing.
29 April 2016
© Allison J. Gong

This week it has been very windy on the coast. As in hope-the-next-gust-doesn't-arrive-while-I-am-still-holding-onto-the-door windy. Seriously, the other day I almost wrenched my shoulder when the wind caught a door I was walking through just as I opened it. I should have braced myself before opening that door. The wind also blows around dust and pollen, exacerbating everybody's spring allergies.

Despite all that, the wind is a good thing because it is the driving force behind coastal upwelling, the oceanographic phenomenon that brings cold, nutrient-rich water from depth to the surface. Upwelled water provides the nutrients that primary producers such as phytoplankton require for photosynthesis. The simple equation is: Sunlight + nutrients = photosynthesis. With the days getting longer as we head toward the summer solstice, this is the perfect time of year to be a phytoplankter. (Note: a phyto- or zooplankter is any creature that lives as plankton)

It takes several days of sustained winds from the north to start upwelling along the coast. I record the temperature in one of my seawater tables every day and keep an eye out for decreases that might indicate upwelling. Given that it's been crazy windy since Sunday (today is Wednesday) I thought today would be a good day to collect a plankton sample and see what's going on.

What did I find? Lots of phytoplankton, right on schedule!

Plankton sample collected from the Santa Cruz Municipal Wharf. 27 April 206 © Allison J. Gong
Plankton sample collected from the Santa Cruz Municipal Wharf.
27 April 206
© Allison J. Gong

Most of these critters are diatoms, of which there were several different types. Diatoms are unicellular algae whose cells are encased in a fancy silica shell called a frustule. More on that later. In Monterey Bay, the first phytoplankters to bloom in the spring are usually diatoms; they can take advantage of upwelled nutrients to fuel rapid asexual division so their populations grow quickly. Photosynthetic creatures from diatoms to redwood trees can perform the biochemical magic of capturing light energy and converting it to chemical energy held in molecules containing fixed carbon (e.g., glucose). Diatom blooms provide food for grazing zooplankters such as copepods and krill. These small animals become food for any number of larger animals, and so on up the food chain, so in every sense possible the phytoplankton are the foundation upon which the entire marine food web is based. Interested in saving the whales? Then you should focus your energies on saving the phytoplankton. Seriously.

The largest object in the photo above is a large protozoan ciliate called a tintinnid. They also live in glass shells, only theirs is called a lorica (L: "body armor"). The tintinnids I see most frequently in tows from the Wharf have a clear goblet-shaped lorica that is entirely transparent. These tintinnids are big, for single-celled creatures, up to over 1 mm in length. That's a lot bigger than some multicellular animals!

Tintinnids are frantic little swimmers. They are heavily ciliated, which means they can swim really fast. The one in the photo was tangled up in the phytoplankton and squashed under a cover slip, which conveniently retarded its motion, but in this video you can see its little cilia beating. I added a few seconds of a different tintinnid swimming solo to the end of the video clip, which will give you a better idea of how they swim.


Here are some other plankters from today's sample:

Photo #1 - Diatoms. The large cell with the spines on both ends is Ditylum brightwellii, one of my favorite scientific names. Chaetoceros cells each have long spines at the corners of the cells. The spines link adjacent cells together, forming chains.

The diatoms Ditylum brightwellii and Chaetoceros spp. from a plankton tow collected from the Santa Cruz Wharf. 27 April 2016 © Allison J. Gong
The diatoms Ditylum brightwellii and Chaetoceros spp. 
27 April 2016
© Allison J. Gong

Photo #2 - Chaetoceros. At least two species of diatoms in the species Chaetoceros.

Chaetoceros spp. 27 April 2016 © Allison J. Gong
Chaetoceros spp.
27 April 2016
© Allison J. Gong

Photo #3 - Chaetoceros debilis(?)This species forms spiral chains.

Chaetoceros debilis (I think). 27 April 2016 © Allison J. Gong
Chaetoceros debilis (I think).
27 April 2016
© Allison J. Gong

Photo #4 - Assorted phytoplankton. In this photo the five roundish cells are the dinoflagellate Protoperidinium. They have two flagella, one in a groove that wraps around the cell and one that trails free. The two button-like cells near the center of the picture are (I think) the diatom Thalassiosira. There are two chains of Chaetoceros debilis and several other chain diatoms. That big opaque vaguely bullet-shaped object to the right of center? That's a fecal pellet, probably from a copepod.

Assorted phytoplankton from the Santa Cruz Wharf. 27 April 2016 © Allison J. Gong
Assorted phytoplankton from the Santa Cruz Wharf.
27 April 2016
© Allison J. Gong

Speaking of copepods, as usual they were very abundant, both as adults and as larvae. In terms of numbers of individuals, copepods are likely the most abundant animals in the sea. Copepods are small crustaceans that feed on phytoplankton and are in turn eaten by many larger animals. In life they have beautifully transparent bodies, allowing us to see the beating heart. See for yourself:

And, finally, about those diatom frustules. As I mentioned above, a diatom's frustule is a sculpted shell made of silica (SiO2). It comes in two parts, an epitheca and a hypotheca, that fit together like the two halves of a petri dish. In fact, I use a petri dish as a frustule model for my marine biology students; it is made of roughly the same substance and demonstrates the size relationship between the epitheca and hypotheca.

The large round centric diatoms best show the structure of the frustule. Here's the best photo I was able to take today of one of the very large centrics, Coscinodiscus:

The centric diatom Coscinodiscus sp. 27 April 2016 © Allison J. Gong
The centric diatom Coscinodiscus sp.
27 April 2016
© Allison J. Gong

I hope that later in the season I can take some better photos of these diatoms. They are so beautiful that I really to do them justice. So much diversity early in the season makes me hope for a good productive season. We'll see!

This morning I drove up the coast to Pigeon Point. It was cold and very windy, and I was grateful to have decided to wear all of my layers. I don't remember any cold mornings from last year's low tides, which made me think that perhaps we're returning to a more normal non-El Niño weather pattern. The wind was screaming down the coast from the north, and if it keeps up we should get some upwelling in a few days. Fingers crossed!

Even the pelicans, which can fly through strong winter storms, were having a bit of trouble with the wind:

Pelicans in flight over turbulent seas at Pigeon Point. 24 April 2016 © Allison J. Gong
Pelicans in flight over turbulent seas at Pigeon Point.
24 April 2016
© Allison J. Gong

My favorite kelp grows in the intertidal, and it wasn't having any difficulty at all with the strong surf. It's not large and doesn't form the magestic kelp forests that divers flock to, but it is very charming in its own way. The sea palm Postelsia palmaeformis is a small  (1/3-1/2 meter tall) kelp that lives only on exposed rocks sticking out into the brunt of the waves. It requires the full force of the crashing waves, where other algae would get broken off. They have a thick flexible stipe that bends with the waves and then pops back up. Postelsia is a protected organism and I can't collect it even with my scientific collecting permit, which is fine with me.

Postelsia palmaeformis on exposed outer coast at Pigeon Point 24 April 2016 © Allison J. Gong
Postelsia palmaeformis on exposed outer coast at Pigeon Point
24 April 2016
© Allison J. Gong

This is the kind of environment in which Postelsia thrives:

You can tell how windy it was by the sound of the wind and my inability to hold the camera steady. As the tide comes in the pounding from the waves will only get worse. These little algae are pretty damn impressive!

Pigeon Point has always been a good place to see the 6-armed stars of the genus Leptasterias. Unlike the five arms that most of the local asteroids have, Leptasterias has six. And unfortunately for us naturalists, the taxonomy of the genus is incompletely understood. All that is agreed upon is that there are several species in the genus. This is referred to as a species complex, acknowledging that the genus contains more than one species but that the species have yet to be definitively described.

Leptasterias sp. at Pigeon Point. 24 April 2016 © Allison J. Gong
Leptasterias sp. at Pigeon Point.
24 April 2016
© Allison J. Gong
Leptasterias sp. at Pigeon Point. 24 April 2016 © Allison J. Gong
Leptasterias sp. at Pigeon Point.
24 April 2016
© Allison J. Gong
Leptasterias sp. at Pigeon Point. 24 April 2016 © Allison J. Gong
Leptasterias sp. at Pigeon Point.
24 April 2016
© Allison J. Gong
Leptasterias sp. at Pigeon Point. 24 April 2016 © Allison J. Gong
Leptasterias sp. at Pigeon Point.
24 April 2016
© Allison J. Gong

As you can see, these stars vary quite a bit in terms of arm thickness and color pattern. Most of the time they are blotchy but the blotches can be pink, gray, orange, or cream-colored. Some of the stars have slender arms with very little taper, while others have thicker arms that taper strongly to the tips. For the time being, until the sea star systematists come to consensus about the species in this genus, I'll refer to all of them as Leptasterias sp.

Most of the Leptasterias that I see in the field are in the size range of 1-4 cm in diameter, usually no longer than my thumb. Today I saw a big one, which would have been about the size of the palm of my hand.

Leptasterias sp. at Pigeon Point. 24 April 2016 © Allison J. Gong
Leptasterias sp. at Pigeon Point.
24 April 2016
© Allison J. Gong

The reason this star doesn't look quite as big as that in the above photo is that it was eating when I disturbed it. The star was humped up over its breakfast!

Leptasterias sp. at Pigeon Point 24 April 2016 © Allison J. Gong
Leptasterias sp. at Pigeon Point
24 April 2016
© Allison J. Gong

The unfortunate breakfast item, the turban snail Tegula funebralis, was about 2 cm in diameter. It seems like a very large and well-protected prey item for a star this size, doesn't it? And yet, there it is. The animal is always right, and Leptasterias certainly knows what it should be eating.

And lastly, because they were just so beautiful and I can't help myself, I'm going to close with photos of anemones.

Anthopleura sola at Pigeon Point 24 April 2016 © Allison J. Gong
Anthopleura sola at Pigeon Point, surrounded by encrusting and upright coralline algae
24 April 2016
© Allison J. Gong
Anthopleura xanthogrammica at Pigeon Point 24 April 2016 © Allison J. Gong
Anthopleura xanthogrammica at Pigeon Point
24 April 2016
© Allison J. Gong
Anthopleura sola at Pigeon Point 24 April 2016 © Allison J. Gong
Anthopleura sola at Pigeon Point
24 April 2016
© Allison J. Gong

Take that, charismatic megafauna!

So. Last week when I looked at my sand dollar larvae I wasn't at all sure what to make of them. I thought that all of the offspring from one of the matings (F2xM1) were going south and didn't know how much longer they would survive. The offspring from the other two matings seemed to be doing much better.

Fast forward a week and a half and my, how things have changed. I have some juvenile sand dollars now! And so far they are all from the F2xM1 mating, the ones that had started looking strange and that I thought might die. I'm surprised that any of the larvae metamorphosed, as my general understanding of sand dollars was that competent larvae settle among adults of their species, so that when they finish metamorphosis they would be in a suitable location to grow up. However, the animals is always right, and in this case I was happy to learn that my understanding was wrong.

This larva is almost competent. The main part of its body is almost completely filled by the juvenile rudiment (the tannish structure on the left side of the more reddish stomach) and the arms are shorter.

Almost-competent pluteus larva of Dendraster excentricus, age 30 days. 22 April 2016 © Allison J. Gong
Almost-competent pluteus larva of Dendraster excentricus, age 30 days.
22 April 2016
© Allison J. Gong

And here is a video of a trio of competent larvae.

Their bodies are almost entirely opaque now but they are unquestionably pluteus larvae.

As metamorphosis begins, the tube feet in the juvenile rudiment rupture through the body wall and the animal starts sticking to a hard surface, in this case a glass slide. For a while the animal is suspended between the larval and juvenile forms, in a state I call a larvenile. Hopefully the time spent in the larvenile stage is short, as to be neither larva nor juvenile is a bad thing. I've seen both sea urchins and sea stars get stuck in the larvenile stage, and they all died.

Larveniles are strange things. See for yourself.

In this video the right side of the animal (not the anatomical right but the right side of the image as it is presented on the screen) is the juvenile, and the left side is the larva. The larva half still has its fenestrated arm rods, which will eventually be dropped and left behind. It also retains for the time being the ciliated band which it used both to swim and to capture food. Another weird feature of the larvenile is the transition between the bilateral symmetry of the larva and the pentaradial symmetry of the juvenile. The bilateral symmetry has been more or less obliterated by the process of metamorphosis, but there isn't enough of the juvenile to have complete pentaradial symmetry yet.

And, finally, metamorphosis is complete and a little sand dollar walks around on tube feet.

Yesterday this animal was a larva, and today it's a juvenile. The sea urchins do the same thing. But these sand dollars have done everything faster than the urchins, and that includes development immediately after metamorphosis. You may recall that the purple urchins have only five tube feet when they metamorphose, and they struggle to coordinate them to walk. From what I can see these sand dollars have at least twice that many tube feet very shortly after metamorphosis, and they can walk much more quickly.

The tube feet themselves are different, too. Urchins' tube feet are suckered and look like little plungers. Sand dollars' tube feet have those pincher-looking tips (although I haven't seen them open up and grab things yet). Adult sand dollars live partly buried in sand and don't use their tube feet to cling to surfaces; they do use their tube feet to grab food, though.

Speaking of food, I don't know what these juvenile sand dollars will be able to eat. Fortunately I have a while to figure out what to try feeding them, as their mouths won't open up for at least a week (I hope). While it's easy to observe what happens on the surface of the animal as it metamorphoses, it's impossible to see what's going on with the internal reorganization of the body. I do know that an entire new gut will have to be formed before the animal can eat. In the meantime it will have to survive on energy stores stashed in all that opaque part of the body.

Stay tuned!

Yesterday I went over to the Seymour Center to talk to the person at the front desk about arranging a field trip visit for a class I'll be co-teaching this summer. When I walked through the exhibit hall into the office wing there were a couple of staff members coming the other way down the hall, gesticulating excitedly towards the door that leads to the garden area on the coastal bluff. My first thought was "Whale!" but when I looked out at the water I couldn't see anything of particular interest in the water.

"No! Look on the wall!" they said.

"What? The barn swallows?" I asked. There were two swallows flying around under the patio. Why are they getting all excited about barn swallows? I asked myself. They kept pointing so I went over to the window for a closer look and saw this creature hanging on one of the light fixtures:

Little furry creature at Seymour Marine Discovery Center. 20 April 2016 © Allison J. Gong
Little furry creature at Seymour Marine Discovery Center.
20 April 2016
© Allison J. Gong

It's a bat! A very small one, about the length of my thumb and about twice as wide due to the fur. It had chosen the light fixture for its daytime roost and was sleeping. Here's a picture of its little face:

Bat on light fixture at the Seymour Marine Discovery Center. 20 April 2016 © Allison J. Gong
Bat on light fixture at the Seymour Marine Discovery Center.
20 April 2016
© Allison J. Gong

I know very little about the bat species in California. However, I did some poking around and now am fairly certain that this bat is in the genus Myotis, possibly M. californicus. There are many other species of Myotis, collectively referred to as mouse-eared bats because of their long ears.

Yesterday I couldn't stick around long enough to see if the bat would fly at dusk. I think that quite often daytime roosts are temporary, so there's no reason to expect the bat to return. Tomorrow I'll be at the lab most of the day and will be able to see for myself.

Remember that one batch of sand dollar larvae that were looking weird on Monday? Well, they still look weird. In fact, all of the larvae looked the same yesterday as they did on Monday, which seems strange, considering how quickly they galloped through development for the first three weeks of larval life. It's as though they've entered some stasis period during which developmental progress slows way down. Or maybe I just can't see the signs of change.

Pluteus larva of Dendraster excentricus, age 23 days. 15 April 2016 © Allison J. Gong
Pluteus larva of Dendraster excentricus, age 23 days. Mating: F2xM1. Diet: Rhodomonas only
15 April 2016
© Allison J. Gong

If I had seen these larvae for the very first time yesterday, I might not suspect that anything was strange. But having watched them twice weekly since fertilization and knowing how different they looked a week ago, my Potential Weirdness-o-Meter™ is redlining. These larvae have definitely changed in a week, and not in the way that I'm used to echinoid larvae developing. With their much shorter arms and overall stunted appearance, these guys appear to be regressing. However, they aren't dying and they don't really look bad. As I said on Monday, they just look . . . weird.

Remember how I said I'd split this cohort of larvae into two batches and fed them different things? At first I thought this strange appearance was due to the change in diet from a Rhodomonas/Dunaliella mixture to Rhodomonas only. The larva in the photo above was from the Rhodomonas-only jar, and perhaps its odd appearance could be explained by some deficiency in the monoculture diet. Then I continued on my rounds and looked at the larvae from the same mating that were still on the Rhodo/Dun diet.

Pluteus larva of D. excentricus, age 23 days. 15 April 2016 © Allison J. Gong
Pluteus larva of D. excentricus, age 23 days. Mating: F2xM1. Diet: Rhodomonas/Dunaliella mixture.
15 April 2016
© Allison J. Gong
Pluteus larvae of D. excentricus, age 23 days. 15 April 2016 © Allison J. Gong
Pluteus larvae of D. excentricus, age 23 days. Mating: F2xM1. Diet: Rhodomonas/Dunaliella mixture.
15 April 2016
© Allison J. Gong

All the larvae in these photos remained on the mixed diet, and they look pretty much the same as their siblings eating the monoculture diet. So I don't think the change in diet explains the appearance of the larvae.

Okay, then. If it's not the food that accounts for what these larvae look like, maybe it's something about the mating itself. These larvae, from both food treatments, are all full siblings from one mother mated with one father. As full sibs they share, on average, 1/4 of their DNA with each other, which could account for the similarity in their appearances. Perhaps this "strange" look is due more to genetics than to the environment (i.e., food).

I can test this hypothesis by examining larvae from the other crosses. Rather fortuitously, as it turns out, when I spawned the adult sand dollars a little over three weeks ago now, only one male contributed enough sperm for me to use. Three females spawned usable amounts of eggs, so I set up three matings:

  • F1xM1
  • F2xM1
  • F3xM1

The female designated F2 gave the most eggs, and her offspring are the ones that I split into the Rhodo-only and Rhodo/Dun diets. Note that all of the larvae in this little experiment have the same father. This gives me the opportunity to test for maternal effects on development; in other words, having controlled for the effects of different fathers--ha! I make it sound as though I did that on purpose--I can now assume that differences (in growth rate, survivability, and successful metamorphosis if we get that far) between the different matings are at least partially due to differences in egg quality among the three mothers. Or to differing gamete compatibilities between each female and the one male.

So now let's take a look at the larvae from other matings. We'll start with F1xM1:

Pluteus larva of D. excentricus, age 23 days. Mating: F1xM1. Diet: Rhodomonas/Dunaliella mix. 15 April 2016 © Allison J. Gong
Pluteus larva of D. excentricus, age 23 days. Mating: F1xM1. Diet: Rhodomonas/Dunaliella mixture.
15 April 2016
© Allison J. Gong

This larva looks normal to me, or at least what I've come to assume is normal. And wow, that was one filthy cover slip,wasn't it?

The offspring of the F3xM1 mating look very much the same:

Pluteus larva of D. excentricus, age 23 days. Mating: F3xM1. Diet: Rhodomonas/Dunaliella mixture. 15 April 2016 © Allison J. Gong
Pluteus larva of D. excentricus, age 23 days. Mating: F3xM1. Diet: Rhodomonas/Dunaliella mixture.
15 April 2016
© Allison J. Gong
Pluteus larvae of D. excentricus, age 23 days. Mating: F3xM1. Diet: Rhodomonas/Dunaliella mixture. 15 April 2016 © Allison J. Gong
Pluteus larvae of D. excentricus, age 23 days. Mating: F3xM1. Diet: Rhodomonas/Dunaliella mixture.
15 April 2016
© Allison J. Gong

And here's a short video of that same pair of larvae. They look like they're singing a duet. If I were the clever sort I'd dub in some music; alas, I'm not that clever. Does somebody want to do this for me?

The red-tailed hawk parents across the canyon are being kept busy by their hungry chicks. This year they have a trio of youngsters to feed--last year they successfully fledged two chicks--but apparently they've not had any trouble finding enough food for all three of them. If I had the luxury of staying home all day to watch hawks I'd probably get to see several feedings throughout the day. As it is, most days this week I've been able to watch a late afternoon feeding when I come home.

The chicks are now big enough to thermoregulate on their own, and quite often will be left in the nest alone for extended periods. The other day when I was home for lunch I happened to see the mama hawk fly up the canyon and alight in a pine tree close to my house. A quick check of the nest showed that the chicks were sleeping (I didn't see any fuzzy lumps above the rim of the nest) so I concentrated on the mom and was able to take this photo:

Female red-tailed hawk (Buteo jamaicensis), taking a break from nest duties. 13 April 2016 © Allison J. Gong
Female red-tailed hawk (Buteo jamaicensis), taking a mid-day break from nest duties.
13 April 2016
© Allison J. Gong

All told she was away from the nest for about 15 minutes. She basked in the sun, did a bit of preening, and spent quite a lot of time looking down (I assume for prey on the ground). A raven and a pair of Anna's hummingbirds tried to engage her in some extracurricular activity, but she ignored them.

This afternoon I got home at about 17:30 and went out back to check on the nest. Turns out I made it home just in time to view the evening feeding. One of the parents, I couldn't tell which, was feeding the chicks long bloody strips of some mammal that had gray fur. All three chicks were fed. Here, see for yourself:

The chicks are growing real feathers now and look like awkward pre-adolescents. They've lost the cuteness of the fluffy baby stage and haven't yet attained the badassness of their parents. In fact, right now they're downright ugly. In the next couple of weeks they'll start looking like punky teenagers as their feathers continue to come in. They'll also spend more time walking around the nest.

Oh, and by the way, the nest is attracting flies now. Good thing birds don't have a keen sense of smell, because it's gotta be pretty stinky up there, what with all the bird poop and rotting bits of previous meals. Also good (for the humans in the neighborhood) that the nest is about 100 feet above the ground.

These sand dollar (Dendraster excentricus) larvae that I've been raising will be 21 days old tomorrow, and they are still on the fast track. They're developing much more quickly than any of the sea urchin cohorts I have raised. Some of them already have juvenile rudiments with tube feet visible. With the urchins (Strongylocentrotus purpuratus) this is the age when I worry about the cultures crashing for no apparent reason, and so far these sand dollar plutei look great. I hope I didn't jinx them by writing that. In any case, the sand dollars are known to go through larval development more quickly than their sea urchin cousins, so my larvae appear to be playing by the book, at least as far as timelines go.

Just for kicks I took the largest full-sib cohort I had and split it into two batches. One batch I'm feeding the recommended combination of Rhodomonas sp. (red) and Dunaliella tertiolecta (green), and the other I'm feeding Rhodomonas sp. only. I've been able to raise urchin larvae through metamorphosis on a diet of Rhodomonas so I assumed that this food might work for the sand dollars as well. It turns out, however, that the Rhodomonas-fed larvae look a little strange now.

Pluteus larvae of Dendraster excentricus, age 19 days. 11 April 2016 © Allison J. Gong
Pluteus larvae of Dendraster excentricus, age 19 days.
11 April 2016
© Allison J. Gong

Their bodies have become more opaque and compact; they've shrunk to a length of 450-500 µm. I wonder if this is the first stage in metamorphosis. I didn't see a well-defined juvenile rudiment in any of the larvae I examined but that doesn't mean it isn't there. And although they look weird and deformed, they don't necessarily look bad. They just don't look . . . right.

On the other hand, there may indeed be something wonky going on. I have a jar of siblings of these larvae being fed a red/green diet, and they look totally different.

Pluteus larvae of Dendraster excentricus, age 19 days. 11 April 2016 © Allison J. Gong
Pluteus larva of D. excentricus, age 19 days.
11 April 2016
© Allison J. Gong

This is a beautiful 8-armed pluteus larva. It looks great! The arms are nice and long but none of the arm spines are poking through the ends. They appear to be eating well and have grown to a length of 700-800 µm. This is a ventral view, and that oblong blob on the left side of the pigmented stomach is the juvenile rudiment.

Here's a close-up view of the rudiment:

Pluteus larvae of Dendraster excentricus, age 19 days. 11 April 2016 © Allison J. Gong
Pluteus larvae of D. excentricus, age 19 days.
11 April 2016
© Allison J. Gong

See how the rudiment is crowding into the stomach? And if you squint you might be able to talk yourself into seeing a couple of round blobs in the rudiment. These would be tube feet, which I can see as I focus the microscope up and down through the animal's body but which don't show up very well in a photograph.

The next day that I change the water and have a chance to look at these guys under the microscope is Friday. It's only three days from now, but given how quickly the larvae are developing, a lot could happen between now and then. I'm a little nervous.

This morning I went out on the first morning low tide of the season. I was so excited to have the morning lows back that I got to the site early and had to wait for the sun to come up. Awesome thing #1 about early morning low tides: Having the intertidal to myself.

Dawn over Davenport Landing. 9 April 2016 © Allison J. Gong
Dawn over Davenport Landing.
9 April 2016
© Allison J. Gong

The purpose for the trip was to collect some algae for a talk I'm preparing; I'll be speaking to the docents at Natural Bridges State Beach at their monthly meeting this coming Wednesday. They invited me to talk to them about algae. I already have a lecture on algae prepared, but last year I set the bar pretty high with this particular audience and want do something a little different. So I'll talk to them for a bit, show them some of my pressings, and invite them to press a couple of specimens. This morning I collected a few pieces of algae and took a bunch of pictures.

The Anthopleura anemones continue to fascinate me. At Davenport Landing there's an area where the rock has eroded and forms a sort of channel. In this channel at low tide the water comes about up to my knees. The rock in the channel remains clear of algae but sometimes contains sand. Scattered over the bottom of this channel are several A. artemisia anemones, which can burrow into the sand when it is present. I've photographed these animals many times, as they are magnificently photogenic and in deep enough water that I can just stick my camera below the surface and click away.

This morning the first anemone I looked at in this channel had some orange gunk on its oral surface. At first I thought it had latched onto a piece of bleached algae, but then noticed that others had the same thing. My second thought was, "Ooh, eggs!" If I were at the lab I'd have sucked up some of the gunk and examined it under the microscope.

Spawning female Anthopleura artemisia at Davenport Landing. 9 April 2016 © Allison J. Gong
Spawning female Anthopleura artemisia at Davenport Landing.
9 April 2016
© Allison J. Gong

Usually when animals spawn the gametes are quickly dispersed by water currents. But this channel is high enough that at low tide it doesn't exchange water with the ocean so there are no currents except those generated by the wind. Awesome thing #2 about early morning low tides: No wind. Once I used the camera as a sort of underwater microscope I could see the granular texture of the orange gunk, which told me that these were, indeed, eggs. Cool! Because I was on a hunt for algae I didn't spend a lot of time censusing these anemones, but I figured that statistically speaking they couldn't all be females. And sure enough, after a very short search I found some males.

Spawning male A. artemisia at Davenport Landing. 9 April 2016 © Allison J. Gong
Spawning male A. artemisia at Davenport Landing.
9 April 2016
© Allison J. Gong
Spawning male A. artemisia at Davenport Landing. 9 April 2016 © Allison J. Gong
Spawning male A. artemisia at Davenport Landing.
9 April 2016
© Allison J. Gong

So today I learned that April is when the A. artemisia anemones have sex. Makes sense, as spring is the time of year when many organisms (algae and invertebrates) in the intertidal reproduce. Reproduce sexually, that is.

Some animals reproduce clonally as well as sexually, and while sexual reproduction tends to be seasonal, clonal reproduction doesn't seem to be. Along the coast of central/northern California we have four species of anemones in the genus Anthopleura:

  • A. artemisia, the moonglow anemone (see above)
  • A. elegantissima, the aggregating anemone
  • A. sola, the sunburst anemone
  • A. xanthogrammica, the giant green anemone

Of these four species, only A. elegantissima clones readily. It does this by ripping its body in half in a process called binary fission. The two halves of the animal pull away from each other and the tissue between them gets stretched thinner and thinner until it rips. Then each former-half heals the wound and gets on with life, completely independent of the other. It sounds rather awful but is a very effective way to form clones of genetically identical units that can monopolize large areas in the intertidal.

Anemone (Anthopleura elegantissima) undergoing binary fission, at Davenport Landing. 9 April 2016 © Allison J. Gong
Anemone (Anthopleura elegantissima) undergoing binary fission, at Davenport Landing.
9 April 2016
© Allison J. Gong

It'll probably take this anemone another day or two to completely tear itself into two pieces. Anemones can continue to clone like this, with each individual splitting into a pair of individuals, for a long time. Eventually this process can form large clones. More about the ecology of these clones in a separate post some time.

Our nesting red-tailed hawks (Buteo jamaicensis) across the canyon have THREE chicks! Last year they successfully fledged two. This year we weren't sure how many chicks were in the nest until I saw three white fuzzy heads today. The proof is in the pudding, as they say. Or more precisely, in this video:

The parents have a lot of work to do in the next few weeks. For us human observers on the ground, it'll be fun watching the chicks get bigger, grow feathers, and hopefully take their first flights. Stay tuned!

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