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The intertidal sculpins are delightful little fish with lots of personality. They're really fun to watch, if you have the patience to sit still for a while and let them do their thing. A sculpin's best defense is to not be seen, so their first instinct is to freeze where they are. Then, if a perceived threat proves to be truly frightening, they'll scoot off into hiding. They can also change the color of their skin, either to enhance camouflage or communicate with each other.

Around here we have a handful of sculpin species flitting around in our tidepools. Sculpins can be tricky to identify even if you have the fish in hand--many of the meristics (things you count, such as hard spines and soft rays in the dorsal fin, or the number of scales in the lateral line) used to distinguish species actually overlap quite a lot between species. The fishes' ability to change color means that skin coloration isn't a very reliable trait. When I was in grad school there was another student in my department who was studying the intertidal sculpins, and she told me that most of the ones we see commonly are either woolly sculpins (Clinocottus analis) or fluffy sculpins (Oligocottus snyderi). I've developed a sort of gut feeling for the gestalt of these species, but I'm not always 100% certain of my identifications.

Sculpin in a tidepool at Asilomar State Beach. The fish is colored pink and brown, to match its surroundings in the tidepool.
Sculpin at Asilomar State Beach
2019-07-04
© Allison J. Gong

Anyway, back to the camouflaged sculpins. The ability to change the color of the skin means that sculpins can match their backgrounds, which comes in very handy when there isn't anything to hide behind. Since the environment is rarely uniformly colored, sculpins tend to have mottled skin. Some can be banded, looking like Oreo cookies. The fish in this photo lives in a pool with a granite bottom. The rock contains large quartz crystals and is colonized by tufty bits of mostly red algae. There is enough wave surge for these fist-sized rocks to get tumbled about, which prevents larger macroalgae from colonizing them.

Other shallow pools higher up in the intertidal at Asilomar have a different type of rocky bottom. The rocks lining the bottom of these pools are whitish pebbles that are small enough to be tossed up higher onto the beach. I don't know whether or not these pebbles have the same mineral content as the larger rocks lower in the intertidal, but they do have quartz crystals. The pebbles are white. So, as you may have guessed, are the sculpins!

Sculpins on a gravel bottom in a tidepool at Asilomar State Beach. The fish are white and gray in color, to match the color of the gravel in their pool.
Sculpins at Asilomar State Beach
2019-07-04
© Allison J. Gong

Other intertidal locations have different color schemes. On the reef to the south of Davenport Landing Beach, you will see a lot of coralline algae. Some pools are overwhelmingly pink because of these algae. Bossiella sp. is a common coralline alga at this location.

What color do you think the sculpins are in these pools?

Give yourself a congratulatory pat on the back if you said "pink"!

Sculpin in a tidepool at Davenport Landing. The fish is mottled pink and brown, for camouflage among the pink coralline algae in the pool.
Sculpin and coralline algae (Bossiella sp.) at Davenport Landing
2017-06-27
© Allison J. Gong

Sculpins aren't the only animals to blend in with coralline algae. Some crustaceans are remarkably adept at hiding in plain sight by merging into the background. Unlike the various decorator crabs, which tuck bits and pieces of the environment onto their exoskeletons, isopods hide by matching color.

Turning over algae and finding hidden creatures like these is always fun. For example, I saw these isopods at Pescadero this past summer. See how beautifully camouflaged they are?

Sometimes, when you're not looking for anything in particular, you end up finding something really cool. Last weekend I met up with students in the Cabrillo College Natural History Club for a tidepool excursion up at Pigeon Point. We were south of the point at Whaler's Cove, where a staircase makes for comparatively easy access to the intertidal.

Photo of Whaler's Cove just south of Pigeon Point, during an autumn afternoon low tide
Whaler's Cove at Pigeon Point
2019-11-24
©Allison J. Gong

It's fun taking students to the intertidal because I enjoy helping them develop search images for things they've never seen before. There really is so much to see, and most of it goes unnoticed by the casual visitor. Often we are reminded to "reach for the stars," when it is equally important to examine what's going on at the level of your feet. That's the only way you can see things like this chiton:

A chiton (Mopalia muscosa), heavily encrusted with a variety of red algae, at Whaler's Cove.
Mopalia muscosa at Whaler's Cove
2019-11-24
© Allison J. Gong

Mopalia muscosa is one of my favorite chitons. It is pretty common up and down the California coast. However, like most chitons it is not very conspicuous--it tends to be encrusted with algae! This individual is exuberantly covered with coralline and other red algae and has itself become a (slowly) walking bit of intertidal habitat. It is not unusual to see small snails, crustaceans, and worms living among the foliage carried around by a chiton. Other species can carry around some algae, but M. muscosa seems to be the most highly decorated chiton around here. I showed this one to some of the students, who then proceeded to find several others. A search image is a great thing to carry around!

Compared to the rocky intertidal, a sandy habitat can be a difficult place to live. Sand is inherently unstable, getting sloshed to and fro with the tides. Because of this instability there is nothing for holdfasts to grab, so there are many fewer algae for animals to eat and hide in. Most of the life at a sandy beach occurs below the surface of the sand, and is thus invisible to anyone who doesn't want to dig. There's a beach at Whaler's Cove where I've found burrowing olive snails (Olivella biplicata) plowing along just below the surface. I wanted to show them to the students, so I waded in and rooted around. I did find Olivella, but I also found a burrowing shrimp. I think it's a species of Crangon.

Shrimp on sandy bottom of a shallow tidepool at Whaler's Cove. The shrimp is colored to match the sand.
Shrimp (Crangon sp.) at Whaler's Cove
2019-11-24
©Allison J. Gong

Now that is some damn fine camouflage! If the shrimp didn't cast its own shadow, it would be invisible. Even so, it was clearly uneasy sitting on the surface like that. I had only a few seconds to shove the camera in the water and snap a quick photo before the shrimp wriggled its way beneath the sand again.

As I've said before, observation takes practice and patience. To look at something doesn't mean you truly see it. That's why it is so important to slow down and let your attention progress at the pace of the phenomenon you're observing. If the only things that catch your eye are the ones that flit about, then I can guarantee you will never find a chiton in the intertidal. And wouldn't that be a sad thing?

Autumn is migration season in California. We all know that, in the northern hemisphere, birds fly south for the winter and return north for the summer. And indeed, this is a very good time to go bird watching along the Pacific Flyway, as migrating birds stop to rest and feed at places such as Elkhorn Slough. Here in Santa Cruz, autumn is punctuated by the return of monarch butterflies (Danaus plexippus), roosting in eucalyptus trees at Natural Bridges State Beach and Lighthouse Field.

Since 1997 the Xerces Society for Invertebrate Conservation has been tracking monarch sightings on their migrations between the western U.S. and Mexico. They conduct a volunteer butterfly count every Thanksgiving. More recently, community science data sources such as iNaturalist provide much of the information.

Xerces Society Western Monarch Thanksgiving Count. 2019. Western Monarch Thanksgiving Count Data, 1997-2018. Available at www.westernmonarchcount.org.

This morning, before it got warm, I went to Natural Bridges to see how the monarchs were doing. I wanted to photograph clumps of butterflies dripping from tree branches. It seemed, however, that there aren't as many butterflies as I remember from previous years. The clusters were not nearly as large or as dense as they should be. And the data shown in the figure below do demonstrate a precipitous decline in monarch since 2017. We're still a couple of weeks away from this year's Thanksgiving count, and there is still a chance that the butterflies might arrive in larger numbers.

Xerces Society Western Monarch Thanksgiving Count. 2019. Western Monarch Thanksgiving Count Data, 1997-2018. Available at www.westernmonarchcount.org.

Trained observers know how to estimate the number of butterflies in a cluster like this. The numbers of butterflies at various roosting sites are aggregated to assess overall population sizes.

Monarch butterflies (Danaus plexippus) at Natural Bridges
11 November 2019
© Allison J. Gong

This morning I did see one butterfly that had a tagged wing. It was wearing a green Avery round sticker, with some writing in what looks like black Sharpie. The color of the sticker was very close to the green of the surrounding foliage, so I wasn't even able to see the sticker until I downloaded the pictures from the camera.

Monarch butterflies (Danaus plexippus), including one with a green tag, at Natural Bridges
11 November 2019
© Allison J. Gong

At first I thought the tag resulted from an official scientific project or undertaking, but it turns out that anyone can tag a monarch. The tags are used to track migration of the butterflies. There doesn't seem to be a central depository of tags and their origins, so knowing the color of the tag doesn't tell me where this particular butterfly came from.

Once the sun hits the butterflies and they begin to warm up, the clusters start breaking apart. Butterflies open and close their wings, exposing the darker dorsal surfaces to the sun and warming up their flight muscles. Sometimes they dislodge one another.

On a cool morning like this, many of the butterflies that fell out of the clump couldn't fly yet, and landed on the ground. The boardwalk is perhaps not the safest place for a butterfly to wind up, but at least in a monarch sanctuary such as Natural Bridges the visitors are knowledgeable and look out for the butterflies' safety.

Monarch butterfly (Danaus plexippus) on the boardwalk at Natural Bridges
11 November 2019
© Allison J. Gong

As I wrote before, the butterflies we see at Natural Bridges this year were not born here. This means that their survival to this point has depended on healthy conditions in the Pacific Northwest and the western slopes of the Rocky Mountains, where they lived as caterpillars and emerged from their chrysalises. This also means that planting milkweed for monarch caterpillars in California won't help the butterflies that we see here, although it would help butterflies that are destined to overwinter elsewhere. What will help local butterflies--monarchs and otherwise, and all nectar-feeding insects, in fact--is planting California native plants, to provide them with the nutrition they have evolved to survive on.

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Sometimes dead things can be very informative. Not in the same way as their living counterparts, of course, but there are times when observing a dead specimen reveals details that cannot easily be discerned when the creature is alive. For example, most living birds don't let you get a close look at their feet. Dead birds, on the other hand, don't complain and try to maim you when you spread their toes and look for webbing. What does webbing have to do with anything? It tells you whether and how a bird swims, of course.

Cormorants are fish-eating predators. Like their relatives, pelicans, they do plunge-dive from the air into the water. However, cormorants are much more streamlined than pelicans and also chase their prey underwater. A bird locomoting in water has two options for propulsion--it can use its wings to "fly" underwater or use its feet to paddle along.

Dead cormorant on Moss Landing State Beach
2019-10-30
© Allison J. Gong

Take a look at the foot on that dead cormorant. It is clearly webbed, eminently suitable for a bird that uses its feet to swim underwater. The location of the feet also has functional significance. Note how far back they are on the bird's body. Obviously this helps increase the overall streamlining of the body. Now think about how submarines move through water: the prop of a submarine is also positioned on the back of the boat. That's probably not a coincidence.

Any trip to the beach brings opportunities to see creatures that have washed up. Or are in the process of washing up. Sometimes even (relatively) large animals end up beached. The big scyphozoan medusae, for example, have little control over where the currents take them, and find themselves in shallow water close to shore.

Pacific sea nettle (Chrysaora fuscescens) in the Moss Landing harbor
2019-10-30
© Allison J. Gong

Animals made of jelly do not fare well when they encounter land. There were several of these dinner-plate-sized jellies drifting and pulsing lazily in very shallow water. A few had been left stranded by the receding tide and were already drying up. Even the ones that were still alive would probably never get back to deeper water. Fortunately for them, they are blissfully unaware of their imminent demise--sometimes lacking a centralized nervous system with its all-knowing brain would be a blessing.

Death, of course, is a part of life and a very important part of nature. Even knowing that, it can be disturbing to see dead animals washed up on the beach. For most people, the shells and whatnot of invertebrates don't seem to count as dead things, but everybody recognizes a dead bird. And there is a natural human tendency to feel sorrier for things that are more like us. From a biologist's perspective, keeping track of dead animals on beaches can give us a lot of information about conditions in the sea. There is a sort of standard death rate, but deviations above what is considered normal may signify that something is going on. There are volunteers who make monthly patrols along beaches in the Monterey Bay Area, collecting data on the various carcasses that wash up. These data are used to evaluate the overall health of the waters within the Monterey Bay National Marine Sanctuary. Knowing about dead things can teach us about what's going on with the living things.

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