Cups vs. gourds

A couple of months ago I posted about the vernal equinox and the arrival of spring as heralded by the return of the swallows to the marine lab. This spring I’ve been keeping an eye on the mud nests that have been going up under the eaves of one of the buildings. It seemed to me that the swallows were a bit slow getting started with the nest-building, but in the past handful of weeks they’ve gotten more serious about it and have started raising babies.

When the birds are flying, it’s pretty easy to distinguish between barn swallows and cliff swallows because barn swallows (Hirundo rustica) have a very deeply forked tail.

Barn swallow (Hirundo rustica) in flight

Barn swallow (Hirundo rustica) in flight

Cliff swallows (Petrochelidon pyrrhonota), on the other hand, have a more trapezoidal tail that is not forked:

Cliff swallow (Petrochelidon pyrrhonota) in flight

Cliff swallow (Petrochelidon pyrrhonota) in flight

This spring both species nested together under the eave of the Younger Building. When the birds’ little heads are peeking out of the nest you can’t see the tail (obviously) so it’s harder to tell the species apart, especially when the parents are away. Turns out the species’ nests have different shapes: barn swallows have nests that are described as “cup-shaped” while cliff swallows’ nests are gourd-shaped. I’d read this description before but didn’t really understand the distinction; this year it was pretty easy to tell the difference between the two.

In my case, the nests look like this:Swallow nests, LMLI like how the nests are just crammed in together. Most of these are cliff swallow nests, but the right-most three are barn swallow nests. That’s a barn swallow flying directly towards the camera. I’ve seen as many as four babies peeking out of that second-from-the-right barn swallow nest. They’ve obviously fledged, as quite often all the nests are empty, but they will return to the nest as long as the parents keep feeding them.

Here’s a closer view of the two types of nest:

Two cliff swallow nest (left) and one barn swallow nest (right)

Two cliff swallow nests (left) and one barn swallow nest (right)

As recently as this past week I saw parents sticking additional dabs of mud on the nests. Perhaps there will be a second brood once these fledglings leave for good?

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Monsters in the making

Yesterday I collected three very small Pycnopodia helianthoides stars. When I brought them back to the marine lab I decided to photograph them because with stars this small I could easily distinguish between the original five arms and the new ones:

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These guys began their post-larval life with the typical five arms you’d expect from an asteroid. At this stage they are pretty conspicuous because they are the largest arms. The other arms arise in the inter-radial regions between arms. For years now I’ve been wanting to watch juvenile Pycnopodia stars growing their extra arms, and it looks like I finally have my chance. I noted that these stars are all about the same size, but don’t have the same number of arms. It would be interesting to see if the rate of arm appearance and growth is related to how much food the stars have. Hmmm, that sounds like a study I should do.

And then one of the stars started running. And I mean running. Watch:

You might wonder how in the heck they can run so fast, and it’s a valid question. We can actually examine the animal’s scientific name to get an answer. “Pycnopodia” means “dense foot” and “helianthoides” means “sunflower-like.” So these guys have a lot of tube feet, and they use them to run and feed. Imagine how fast we could run if we had more than two feet and could co-ordinate them this well:

So, when these guys (gals?) grow up, they’ll be at least half a meter in diameter with 20-24 arms. With all those tube feet, they’ll be Speedy Gonzales! In fact, they will be the terror of the intertidal–big, fast, and voracious. Anything that can’t get out of their way will be eaten.

We air-breathing land mammals should be grateful that echinoderms never managed to get out of the sea. Can you imagine this monster chasing you down a dark alley, or climbing through your bedroom window?

Posted in Marine biology, Marine invertebrates | 2 Comments

Fouling communities

On 11 March 2011 a magnitude 9.0 earthquake occurred off the coast of Japan. About 14 hours later, at 11:15 a.m. local time a tsunami came through the Santa Cruz Small Craft Harbor. It sank dozens of boats and significantly damaged several of the docks. People were ordered to evacuate the area before the expected arrival of the tsunami, but of course there were those who chose to stay behind and shoot videos like this one (the real action starts at about 1:00):

As a result of the damage to the infrastructure of the marina itself, many of the docks have been replaced since 2011, including those that are closest to the mouth of the harbor. For several years now I have been taking marine biology students to the docks to examine the organisms growing on the undersides of the docks, and this year the biological community is finally getting interesting again. These particular organisms are described as “fouling” because they are the ones that colonize the bottoms of boats and have to be scraped off periodically. They are characterized by fast growth rates and short generation times; many of them are also colonial. The first arrivals settle onto the surface of the docks, and later arrivals can take up residence either on the docks or on their predecessors. A healthy fouling community has a rich diversity of marine invertebrates, algae, and the occasional fish. This semester’s trip to the harbor occurred a few weeks ago, and as usual the students were amazed at the amount and diversity of life on the docks. I remembered to bring the waterproof camera and snapped some shots.

This is what you see when you lie on the dock and hang your head over the edge:

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It’s a mosaic of color and texture, really quite beautiful. You can see that mussels are the largest organisms in this community, and in turn are substrate for a variety of other animals.

Peering a bit closer to take notice of individual animals, you start to see things like this:

A perennial favorite because of its beautiful coloring. It eats my hydroids, though, so I don't like it.

Hermissenda crassicornis, a perennial favorite because of its beautiful coloring. It eats my hydroids, though, so I don’t like it.

One of the colonial hydroids, Plumularia sp. that grow at the harbor.

One of the colonial hydroids, Plumularia sp. that grow at the harbor. This species always grows in this pinnate form. Absolutely gorgeous under the microscope.

These small white anemones (Metridium senile) are about 3 cm tall.

These small white anemones (Metridium senile) are about 3 cm tall.

Feather duster worm, Eudistylia vancouveri, easily one of the most conspicuous animals on the docks.

Feather duster worm, Eudistylia vancouveri, easily one of the most conspicuous animals on the docks.

Colonial sea squirts, Botryllus sp. and Botrylloides sp.

Colonial sea squirts, Botryllus sp. and Botrylloides sp.

Colonial sea squirts, those orange-ish blobs in the last picture, are extremely common in marinas. In this photo, each distinct colored blob is an individual colony, and each colony consists of several genetically identical zooids connected by a protective covering called a tunic. Each teardrop-shaped zooid has its own incurrent siphon (the visible hole) through which it sucks in water, and the zooids in a group within a colony share a single excurrent siphon through which waste water is discharged. In Botryllus, the zooids are arranged into flower-like configurations called systems. In Botrylloides the systems are much less distinctive and wind around over the substrate. I’ve outlined a nice colony of Botryllus in the photo below, so you can see the easily recognized systems.

A colony of Botryllus, with zooids arranged in flower-shaped systems.

A colony of Botryllus, with zooids arranged in flower-shaped systems.

Such a wonderful world of animals and algae, right under our feet. Even people who spend a lot of time around boats don’t pay attention to the stuff on the docks. To me it is a secret garden that is easily overlooked but greatly appreciated when you take a moment to get your face down where your feet are.

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Going, going, gone!

Our Purple beehive, which swarmed on Wednesday (today is Friday), threw another swarm this afternoon.

It remains to be seen if we can recapture them. So far we haven’t been able to see exactly where they’ve settled. Fingers crossed.

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Swarmy weather

For the past week we’ve had rain, sometimes brief downpours and at other times more gentle rain, and the rainy days would be interspersed with sunshine. We were warned by one of our beekeeping mentors that this was “swarmy” weather:  The bees are locked up inside the hive when it rains, and swarm on the days that are going to be sunny. “Watch your hives for swarms!” we were told.

We did take care to minimize swarms from our Apiary #1. We split the hive and gave the original hive frames of blank foundation to work on, hoping that this extra space would counteract any tendency to swarm. It seemed to work on the original hive, but yesterday the split swarmed. Surprise!

Here’s what a swarm looks like when the bees are getting ready to depart. They gather on the front of the hive until a certain critical mass is achieved, then they take off to a temporary landing site nearby.

These girls went down the canyon and decided to alight on the poison oak. All that green stuff you see in the video is poison oak, so nice and shiny. Alex was brave and bushwhacked a path through the poison oak, then he captured the swarm and brought it back up the hill. By the end of the afternoon the bees were safely (and, we hope, contentedly) ensconced in their new home, our Blue hive.

The swarm now lives in our Blue hive. We hope they stay here.

The swarm now lives in our Blue hive.

We hope they decide to stay here.

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True signs of spring

The astronomical onset of spring is the vernal equinox, which this year occurred on Thursday 20 March 2014. The date is determined by the movements of the Earth and the sun, and occurs regardless of weather conditions anywhere on the planet. Some people look to plants for an indication of spring: the first day that a crocus pops up through the snow, or the first blossoms on a cherry tree. For me, I know that spring has sprung when certain birds show up in my world.

The first red-winged blackbirds make themselves heard in January, which is too early to be thinking about spring but at that point in the year it’s nice to be reminded that the days are getting longer. The red-wingeds’ calls are heard throughout February and March; it always makes me smile to hear them lekking. Some time in March I see the first barn swallows at the marine lab, and once they start plastering mud under the eaves I know that spring is here.

A few years ago the swallows chose a site sort of under a stairway to build their nest. They started plastering mud in a corner of the wall and constructed a neat little home in which to raise their young. That year they raised four babies successfully.

At this point they're the same size as their parents.

At this point they’re the same size as their parents.

The parents were still feeding them, but the babies almost didn’t fit into the nest anymore. It was so cute. I’d walk under them to get to the door and they’d all pivot their heads down to look at me.

The parents were pretty blase about people walking under their nest all day:

The parentsIt was up to us to make sure we didn’t get pooped on. Sometimes you’d have to dodge the splat.

Once the babies fledge and start feeding themselves, we get barn swallows swooping around the courtyard. They seem to be more active in the afternoons, when the wind picks up. They look like they’re having so much fun, zooming around like miniature 737s.

I bet it’s fun to be a swallow in the springtime.

 

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More fun in the intertidal

This past Tuesday and Wednesday afternoon I took my marine biology students to the rocky intertidal at Natural Bridges State Beach. We completely lucked out with the weather; the storm system that brought some of the rain that we desperately need had cleared out, leaving calm, clear seas and little wind. Perfect weather for taking students out in the field, in fact.

First of all, we didn’t see any stars. Not that I was looking for them, particularly, but I was keeping an eye out for them and at this time last year I would have seen many Pisaster ochraceus hanging out in the pools and on the rocks. Here are a couple of pictures I took at Natural Bridges in years past:

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The stars, when present, are prominent residents of the mid-intertidal zone, where they feed on mussels. But now, alas, there don’t seem to be any. They WILL come back, and it will be interesting to monitor their population recovery.

I enjoy taking students in the field because many of them have never been there before, and it’s always fun looking at a familiar scene with fresh eyes. When everything is new, it is very easy to be excited and enthusiastic, which these students are.

We saw, among other things:

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Fish! The fish on the right was about 15 cm long. I think it’s a woolly sculpin (Clinocottus analis), but IDing sculpins in the field is pretty tricky.

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This fish was much smaller, only about 10 cm long. It could be a fluffy sculpin (Oligocottus snyderi), or it could be a smaller woolly.

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This is an encrusting sponge, Haliclona sp. I’ve seen it in shades of rosy pink, too. The large holes are oscula, the sponge’s excurrent openings. And that’s a big gooseneck barnacle (Pollicipes polymerus) hanging down from the top of the picture.

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An assortment of intertidal critters sharing space on a rock. How many chitons can you spot?  How many barnacles?  How many limpets?

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This is one of my favorite intertidal animals, the owl limpet (Lottia gigantea). These large limpets are farmers. They keep an area clear of settlers by grazing at high tide. You can see the marks left by this individual’s radula. The limpets also manage their farms, letting the algal film grow on one section while feeding on another.

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I love macro shots like this! The green tufty stuff is Cladophora columbiana, a filamentous green alga. Isn’t it a vibrant green color? To give you an idea of how fine the Cladophora filaments are, that snail in the background is about the size of a quarter.

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And last, a gratuitous anemone shot. Ahhh, Anthopleura xanthogrammica, what a photogenic creature!

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