Tomorrow my students will be examining cnidarian diversity in lab, so early this morning I went to the harbor to collect hydroids. Or ‘droids, as I refer to them. These are not the droids of Star Wars fame, such as C-3PO and R2D2, but rather colonial cnidarians. As such, they are made up of many iterated units (called zooids) connected by a shared gastrovascular cavity (GVC), or gut. Despite how weird it seems to most people, this sort of colonial lifestyle is not uncommon among marine invertebrates; it occurs in several other taxa as well, most notably the Anthozoa (sea amenones, corals, and others), Bryozoa (bryozoans such as Membranipora), and Urochordata (sea squirts).
On my various trips to the harbor over the past few months I’ve been keeping an eye out for ‘droids, as I knew I’d need them. The one species I was glad to see getting established this summer is called Ectopleura crocea; it is one of the non-native members of the fouling community that shows up in harbors all along the California coast. It is a most beautiful animal, and quite conspicuous when it is present. This year I’ve seen it growing lustily on the docks, mussels, and any manmade object that has been marinating in the water for a while.
The stalks in this particular colony are 3.5-4 cm long. Each one of those tufts at the end of a stalk is a hydranth, the part of the zooid that bears the feeding tentacles and mouth. Hydroids are cnidarians and thus have stinging cells along their tentacles, which form a ring surrounding the mouth.
Ectopleura hydranths actually have two concentric rings of tentacles, with the mouth in the middle of the smaller ring. Between the tentacle rings there is a sort of empty space that is filled with reproductive structures called gonophores when the colony is preparing for sexual reproduction. In some hydroids gonophores release medusae, but in Ectopleura they release gametes. A given colony is either male or female, and any one of the hydranths can become reproductive and develop gonophores.
Hydroids are definitely animals whose beauty is better appreciated when observed under a microscope:
In the colonies of E. crocea that I’ve observed before, mature male gonophores are a solid white and female gonophores are pinkish. I collected three clumps of Ectopleura today, and none of the gonophores are mature. You can see why the common name for this animal is “pink mouth hydroid,” as the mouth is borne on a pink tubular structure called a hypostome.
I’ve tried multiple times to grow this animal in the lab. There are some experiments on resource sharing in hydroids that I’ve been wanting to do for years but haven’t yet found the right species to work with. In captivity Ectopleura eats well, then after several days all the hydranths drop off and the colonies die. I’ve never had success getting them to regrow their hydranths, either. So I bring them in for short periods and observe them up close while I can.
I always find that autumn is a tough season for me, in terms of maintaining enthusiasm and fascination with the world around me. I feel, like most creatures, that autumn is a time to hunker down and take it easy until the winter solstice, after which we’ll be gaining daylight again instead of losing it. Even if we get blasted by El Niño storms in January and February, it will be easier for me to feel energized simply because the days will be getting longer.
However, even though I really want to hole up with books, tea, and knitting (hi, Junkies!) life goes on and I can’t ignore the siren call of the natural world. This morning I went whale watching with some of my students. It was a class trip organized by the other instructor for the course, and almost all of my students came along. If you know me, you probably know that I have a history of horrendous seasickness. As in so awful that none of the OTC meds even touch it, and although I have tried some of the prescription meds they all make me so drowsy that I can’t drive or even really stay awake.
It has been a good year for whale watching in Monterey Bay. Humpbacks have been everywhere the past several weeks, showing off all their acrobatic skills and lunge-feeding right off the beaches in Santa Cruz. So it really is a fantastic time to go whale watching, and since I had to go with my class I asked my doctor about other seasickness drugs to try. She gave me something that has worked for other people, including the pharmacist who filled my prescription, and although I’ve been burned before by the words, “Oh, this will work. You’ll be fine!” hope springs eternal and I tried it. And by George, I think it worked! Not that the seas were bad at all, but I think that if I’d gone drug-free I would have been substantially less happy out there.
We did see whales, but for the most part they were pretty far away. They didn’t spend much time at all on the surface, just a breath or two and then a show of the flukes as they dove to deeper water. The only breaches we saw were way off in the distance. There were a lot of common murres swimming around, which were extremely fun to watch. They are ecologically similar to penguins in the southern hemisphere and even resemble penguins, with their “tuxedo” plumage.
I was trying to photograph some murres on the surface when this happened:
The rocks in the background are covered with adult pelicans. The upper dock is occupied by Brandt’s cormorants (Phalacrocorax penicillatus), which appear to require more personal space than do pelicans, and one of what I think is a great egret (Ardea alba). The lower dock is almost submerged by California sea lions (Zalophus californianus).
I’m counting today as a minor victory, and I’m grateful to have been able to enjoy it. This is the first time I’ve been out that far on Monterey and not wanted to die. ‘Tis the season for gratitude, isn’t it?
ORGANISM OF THE MONTH: Pugettia producta, the kelp crab
For a few months now, I’ve had a pet kelp crab running around in one of my seawater tables. I don’t remember where I collected it, or even whether or not I collected it at all; quite often crabs and other animals arrive as hitch-hikers on kelp that we bring into the lab to feed urchins, and I end up with many cool critters in my care that way. However she got here, this crab has been rather a pain in the butt during her stay with me. For at least a couple of weeks she got stuck in the drain of the table and would not come out despite three experienced marine biologists (including yours truly) trying to persuade her by altering water flow and offering food bribes. Then she disappeared from the table drain and I assumed that she had gone all the way through to the floor drain, where she could live quite happily for all eternity. Then she suddenly showed up again in one of my urchin baskets. When she came back up from the drain and how long she’d been hiding, I’ll never know.
Wondering why I keep referring to this crab as “she”? It’s because I know for certain that she’s a female. Here’s the secret to how you can determine the sex of brachyuran crabs (most of the common crabs: kelp crabs, shore crabs, rock crabs, even Dungeness crabs): You look at the shape of the abdomen, which is curved forward on the underside of the body. See here:
The abdomen is the broad flat upside-down-U-shaped panel that covers about half the width of the ventral surface. Female crabs brood their embryos under the abdomen, hence the broad shape. Male crabs of the same species have a much narrower, pointed abdomen.
Since her escapade with the drain the crab has been more, shall we say, co-operative. She’s still free to scurry around at will in the table, but I haven’t found her doing anything objectionable such as tormenting urchins or trying to get down the drain again. She has also been eating well.
Until this past week, that is. On Monday she accepted a piece of food but then abandoned it without even tasting it. On Wednesday she fled from the food, which I took to mean that she was getting ready to molt. Like all arthropods, crustaceans molt their exoskeletons every so often. The decapod crustaceans I’m most familiar with tend to off their feed for a few days before molting, and usually the actual shedding of the exoskeleton occurs at night. Then we show up the next day and voilà! like magic there’s a new, bigger crab in the table.
Ms. Kelp Crab stopped eating on Monday of this week. Today (Friday) I didn’t get to the lab until about noon, and one thing I noticed in the table was an empty carapace. Sure enough, she had molted. It took a little hunting to find the crab herself, but she wasn’t really hiding and her new exoskeleton had already hardened. I’m pretty sure she’ll eat on Monday.
Living in a rigid exoskeleton means that a crustacean can increase in body size only in the time period between when an old exoskeleton is shed and the new one hardens up. I’m always curious about exactly how much crabs grow when they molt. So today I measured the crab and her old carapace at the same place, halfway between the two points on the lateral edges of the carapace. Huzzah for empirical data! The old carapace measured 27.6mm across, and the new one 33.8mm, for an increase in width of 6.2mm or 22.5%. Mind you, this is simply the increase in one linear dimension of the crab’s body. To obtain a more accurate measurement of body size increase, I’d have to have weighed the crab immediately before her molt and after it. Still, it does give an estimation of how much bigger a body part can get when a crab molts.
. . . must come to an end, so they say. And Scott’s and my little experiment growing Pisaster ochraceus came to its end when the last of our teensy stars gave up the ghost a week ago. We aren’t entirely surprised, as nobody before us had succeeded in growing these guys in the post-larval stage, but it’s still sad to see the empty paddle table and disappointing to know that we haven’t really added to the body of knowledge about how to grow them.
But we did make a small bit of progress, at least to further our own understanding of exactly how difficult it is to do what we attempted. To summarize, here’s a timeline of what we did and what happened:
18 and 20 May 2015 — Collected adult stars from local intertidal sites. Made up the solution of “magic juice” (100 µM 1-methyladenine).
2 June 2015 — Shot up stars with 1-MA. Got usable amounts of gametes from a total of three stars: 2 Purple (1 female + 1 male) and 1 Orange (female). After examining gametes to make sure they were okay, set up two matings: Purple x Purple; and Orange x Purple. The Purple x Purple embryos went through the earliest developmental stages just fine. The Orange x Purple embryos got off on the wrong foot and never recovered.
5 June 2015 — Purple x Purple embryos began undergoing gastrulation. Began feeding them. Orange x Purple embryos all dead.
20 July 2015 (age 48 days) — Larvae began settling.
27 July 2015 (age 55 days) — Counted a total of ~22 tiny stars in the jars. Removed a few to measure, and they were all 500 µm or smaller in diameter. It was very difficult keeping track of things this tiny in our 1-gallon jars.
13 August 2015 (age 73 days) — Paintbrushed out all of the little stars into a bowl and divvied them up into six food treatments. Replaced bowls in the paddle table to provide very gentle stirring.
21 August – 7 September 2015 — Stars died off in all but one of the food treatment bowls. By 7 September (age 96 days) the only surviving stars (N=4) were the ones we kept in a bowl with a small piece of mussel shell.
11 September 2015 (age 100 days) — And then there were three.
28 September 2015 (age 117 days) — Two survivors + 1 corpse.
2 October 2015 (age 121 days) — And then there were none.
In a nutshell, the larval development went fairly well, as we expected, and the post-larval survival sucked, also as we expected. We did manage to get those last two stars to survive 48 days post-metamorphosis, which is something. I’m not sure how much credit we can take for that, though, as I suspect that the reason the other juveniles died had to do with poor water quality as much as lack of food.
Here’s what I think might have been going on: We are in our second consecutive year of elevated seawater temperature, and coupled with the massive El Nino that yesterday was proclaimed to be among the strongest ever this means that coastal animals are being subject to higher-than-normal temperatures. In ectothermic poikilotherms such as marine invertebrates, metabolic rate is directly related to environmental temperature. Thus, higher ambient seawater temperature should result, all else being equal, in a faster growth rate.
This sounds like it might be a good thing for the Pisaster larvae, especially if predation and other risks are higher in the planktonic larval stages than as benthic juveniles. However, I think there’s more to the problem than simple growth rate. What if success as a juvenile depends not only on how quickly an animal progresses through all of its developmental stages, but also on how much time it spends in the different stages? For some larvae, notably the nauplius larva of barnacles, the primary job is to eat as much as possible and deposit energy reserves in the form of oil droplets; these food reserves will be utilized by the second larval stage, the non-feeding cyprid, as it hunts around for a place to establish a permanent home in the benthos. Perhaps part of the job of the developing Pisaster brachiolaria larvae is also to sequester energy reserves. Although no oil droplets were visible in any of the larvae that Scott and I observed this summer, energy could have been stored in other tissues of the larval body.
Back to the problem of post-larval survival. Our larvae began metamorphosing after only 48 days in the plankton. One of our sources has Pisaster ochraceus undergoing metamorphosis at 76-228 days in culture, at temperatures of about 12°C (for the duration of our experiment this summer ambient seawater temps were 15-18.5°C). So, if the warmer temperatures caused the larvae to develop more quickly than normal, and the larvae spent ~25 fewer days in the plankton than they “should” have, they may simply not have had time to accumulate whatever energy reserves they’d need to draw on once they metamorphosed.
That’s just a guess on my part. I also imagine that poor water quality played a part in our juvenile stars’ demise. It proved to be impossible to make potential food available to such tiny animals while keeping their water clean. We thought that stirring on the paddle table might help, and who knows, maybe it did.
In any case, RIP, little guys. Thanks for what you taught us, and I’m sorry we weren’t able to help you succeed.
That cute little Melibe I found last week is still alive, and still super cute. It lost one of the two large cerata on its back the second day I had it, and I wasn’t sure it would be able to survive long without it, but it has hung in there and started growing a replacement. This afternoon it was crawling on the underside of the surface tension in the bowl:
It is extremely difficult photographing transparent animals; this is the best shot I got. You are looking at the animal’s ventral surfaces. It is using its elongate foot to stick to the surface, and the rest of the body is suspended from the foot. The oral hood is wide open and you can see the little blue spots at the base of each tentacle.
The best news is that the tiny Melibe has learned how to eat! The first couple of days I offered it live brine shrimp nauplii, and the Melibe didn’t seem to like the thrashing of the nauplii. It cowered and shrank instead of trying to eat them. Then it occurred to me to mush up the nauplii first, so they wouldn’t be so active. I also thought that the Melibe might be able to eat the mush itself. Aha, success! Except that I wasn’t able to capture any video or photos then.
Today, though, the Melibe did this, while I had the camera all set up and ready to go:
Instead of cringing from the nauplii, today the Melibe was actively going after them. In this video it encloses its oral hood around a handful of nauplii and collapses the hood, forcing the nauplii into its mouth. You can actually see the nauplii stop struggling as they are ingested.
I think the Melibe is growing, too. I’ll have time to measure it on Monday.
Much ado is being made of the fact that Africanized honey bees have recently been found in the San Francisco Bay Area. Most of the articles I’ve read on the subject have disseminated information that is good, but can be confusing to the average person who isn’t a beekeeper. Most people who don’t understand bees fear them, and only want to know: (1) Should I be worried? and (2) How much should I worry?
First, some background: The European honey bee (Apis mellifera) was introduced to North America with the first European settlers on the continent. It is a docile bee, easy to work with, and generally a good honey producer. Several strains, or subspecies, of A. mellifera have been bred over the years, resulting in stocks that beekeepers refer to as Italians (A. mellifera ligustica), Carniolans (A. mellifera carnica), Russians, and others. Beekeepers choose strains of bees that suit their preferences, in terms of temperament, honey production, speed of colony build-up, and disease or parasite resistance.
We began our beekeeping adventures with two packages of Italian bees, which proved to be very sweet and extremely productive. Most of our mentors told us not to expect to harvest any honey our first season, as the bees would be busy growing the colony and finding enough food to feed themselves over the winter, and yet we harvested over 100 pounds of surplus (i.e., beyond what the bees needed to overwinter) honey. Since then we’ve not had to buy packages again and have acquired colonies by either catching swarms (fun!) and splitting our existing hives.
Occasionally a beekeeper has to re-queen a hive, to replace one that has gone missing or is failing to lay well. Sometimes the bees take matters into their own hands(?) and rectify a situation that they feel is lacking; they will build a new queen from one of their sister larvae, who will supplant their collective mother and take over the egg-laying duties. We have re-queened hives that are bitchy, the ones in which the bees fly up at us the moment we crack the hive open and bang into our veils. I don’t like to work with pissy bees, and while I know I shouldn’t be afraid of our bees, I’ve had a bad enough sting reaction to warrant allergy tests that determined I have a mild-moderate allergy to honey bee venom. So I’d much rather work with sweet bees, like Italians or Russians that just look up at us from between the frames or keep going about their business as we tear apart their home.
How and why does a colony of mild-mannered, easy-to-work-with bees become a nightmare to deal with? What happens probably goes something like this. Worker bees may decide, over the course of a season, to supersede their mother and re-queen their colony. The new queen, who is the sister of the workers, flies out and mates with a dozen or so drones from other colonies, then returns to her natal hive to begin laying. If she mated with drones who carry Africanized alleles, then some of her offspring will possess those alleles. A beekeeper with a hive that has become more defensive can change its overall temperament by introducing a new queen that comes from a lineage known for its gentleness.
More about the Africanized bees: Africanized honey bees are the result of inadvertent hybridization between strains of the European honey bee, including the Italian A. mellifera ligustica, and the African bee, A. mellifera scutellata. The African bee was imported to a lab in Brazil in the mid-20th century, when beekeepers were attempting to increase honey production. It escaped from quarantine in 1957 and began hybridizing with the European honey bees that had been established in the New World for centuries. It has been expanding its range northward since; the first reports of Africanized bees in southern U.S. states were in the early 1990s. They have been in southern California since 1994.
An Africanized honey bee has a sting that is no different from that of a European honey bee, and she will still die when she stings someone. The difficulty, as far as humans and livestock are concerned, is that Africanized bees are much more defensive of their colonies and are generally easier to piss off. When they perceive a threat they usually emerge from the hive in great numbers and attack the intruder. They have also been known to chase people long distances and keep attacking. People who accidentally upset a colony of Africanized bees tend to get stung dozens or hundreds of times, and the accumulation of that much venom can be fatal.
The only way to know for certain that a bee is Africanized is to examine her genome for African alleles. We know now that Africanized honey bees are in the Bay Area. Whether or not they become permanently established remains to be seen, but if there’s one Africanized colony surely there must be others.
So, should you be worried? In my opinion, there are lots of things that are more worrying than Africanized honey bees. Then again, where I live they haven’t been around very long and I’ve never encountered a purely Africanized colony. If we have bees in our hives that are pissy we re-queen the colony, so it’s unlikely that any of our colonies will be taken over by Africanized bees. However, this is a biological system we’re talking about, so nothing is guaranteed.
Here in northern California, most beekeepers aren’t too worried about Africanized bees because we think they won’t survive our winters. That said, we’re heading into a pretty strong El Niño event and may not have a cold winter this year, although we all hope it’s a rainy one (and a snowy one in the Sierra Nevada). Plus, with climate change and a generally warming planet, conditions that favor survival of the Africanized bee may soon prevail in much of the U.S. Residents of the southern U.S. should probably take care not to disturb a colony of feral bees because they may be Africanized. Call a beekeeper (not an exterminator!) and let a professional deal with it. Bees (both European and Africanized) that are foraging, though, tend to be focused on the job at hand and won’t bother you unless you bother them first. Just leave them alone and watch from a safe distance.
This morning I was doing some routine cleaning of animal-containing dishes at the marine lab when I noticed a little blob of snot on the outside of the bowl I was working on. Normally I just wipe off blobs like that, but something about this one caught my attention in a different way and I paused to take a closer look at it. What I saw made me glad I hadn’t given it the old Kim-Wipe™ treatment.
This little 3mm blob of cuteness is the tiniest Melibe I’ve ever seen. Melibe is one of my favorite creatures of all time. It’s an entertaining animal that has unfathomable amounts of charm. Unlike most other nudibranchs, which prey on other animals (typically cnidarians, sponges, or bryozoans), Melibe is a filter feeder. It sweeps its large oral hood, visible to the right, through the water to capture plankton. The flat large-ish structures projecting from the animal’s back like wings are cerata, of which there will eventually 4-5 pairs when the slug reaches adult size. The cerata function as gas exchange surfaces; they also contain extensions of the digestive system. When a Melibe is mishandled or stressed, it drops cerata, which can then be regenerated.
Melibe is the most animated of slugs. I dropped a few brine shrimp nauplii on this little guy to see if it would be able to catch them. Unfortunately it looked more like the nauplii were ganging up on the Melibe than the other way around. However, I know from experience that even larger Melibe take a while to figure out how to eat brine shrimp.
But isn’t that the cutest slug you’ve ever seen? It has tiny bright blue dots on its body! Those two little flaps on the top surface of the oral hood are rhinophores. I know they look like ears, but they are chemosensory rather than auditory organs.
And look how fast this little nudibranch can crawl! Remember, it’s only 3mm long, and it’s making pretty good progress getting to the corner of the bowl.
When dislodged from whatever it’s crawling on, Melibe can swim. I thought this one would attach itself to the underside of the surface tension, as they often do, but it thrashed for quite a while before sort of accidentally finding the bottom of the dish again.
And do you know what the best thing about Melibe is? It smells like watermelon. I kid you not. If you touch a Melibe, your finger will smell like watermelon Jolly Ranchers. How could an animal possibly be any cooler than that?
In a desperate attempt to escape from the heat yesterday afternoon I went down to the marine lab and vowed to find something to do that would keep me there for a while even though I had only a few minor chores to take care of. Fortunately there was a lot going on in the ocean. The tide was high, almost completely covering the intertidal benches where I spent so much time this spring and summer. And there, right up against the cliff, were hundreds of seabirds, squawking and squabbling over fish. Pelicans, terns, gulls, and cormorants were all mixed together in a big scrum of activity.
The brown pelican (Pelecanus occidentalis) is described by the Cornell Lab or Ornithology as a “comically elegant bird” and it’s hard not to agree. However, watching them in flight over the ocean makes me reconsider. When I see them in the air I find them to be not just elegant, but graceful as well.
While the birds were making a fuss over anchovies that had been pushed close to shore, six harbor seals (Phoca vitulina) were lounging lazily just off the point. They would roll around at the surface, diving underneath waves as they broke onto the rocks. Because the tide was high the seals were floating over intertidal benches that I explored during the spring and summer. They didn’t seem to be feeding on anything at the time.
As you might expect with all the feeding frenzy going on, a couple of humpback whales came to the show. They were out beyond the kelp bed, far enough away that I could have missed them if I didn’t have my binoculars with me. I didn’t see any lunge-feeding from this pair, which left more food for the birds.
After I’d been watching the feeding activity for about an hour and a half, I heard the familiar high-pitched ‘cheep-cheep-cheep-cheep-cheep’ of one of my favorite local seabirds, the black oystercatcher (Haematopus bachmani).
I love these birds for a couple of reasons: (1) I have NEVER seen a single oystercatcher, I have seen them only in what I assume are mated pairs (there is no sexual dimorphism in this species so it’s impossible to distinguish between males and females); and (2) they almost always show up to keep me company when I’m in the intertidal, especially at Davenport Landing. They are also noisy birds, both in flight and while walking around on mussel beds. They have a dark sooty brown body and a long, stout, bright red beak that contrasts nicely and is the perfect tool for prying open mussels or flipping limpets off rocks. This particular pair didn’t join in the hullabaloo over anchovies, since oystercatchers don’t eat fish. I watched them prowl around on the rock bench, where the tide was really too high for them to have access to the mussels.
I remain grateful for a cool place to retreat to when it gets hot in Santa Cruz. We are in strange times, weather-wise, and I don’t think anybody really knows what to expect over the next few months. All I know is that I hope we don’t get any more of these blazing hot spells.
Let’s just get this out of the way: I live in a paradise of natural beauty. Sometimes I still can’t believe that I get to call this gorgeous place my home. However did I get so lucky?
Case in point. For the last week or so a juvenile humpback whale has been hanging out in a small cove right off the road that winds along the coast in Santa Cruz. Several of my friends had shown me pictures and video of it, but every time I went out I got skunked. I saw lots of seabirds, though, and that itself was pretty amazing.
Pelicans (Pelecanus occidentalis) and Caspian terns (Hydroprogne caspia) plunge-diving? Check. Common murres (Uria aalge) in the air and hanging out on the surface of the water? Check. Attempted kleptoparasitism by a gull on a tern that had caught a fish? Check. That was really cool. Oddly, though, I didn’t see any sooty shearwaters today.
This past Saturday I went down to Mitchell’s Cove and saw some amazing seabird behavior. The pelicans and terns were both plunge-diving, and then being mobbed by gulls and other hangers-on every time they came up with a fish. And in the background there was an unending stream of shearwaters flying from right to left.
I love how the pelicans fly along above the surface, then fold their wings and transform into arrows before shooting into the water. Good thing they don’t have nostrils, isn’t it? The terns do the same thing. Through the binoculars I watched the terns looking down for prey before committing to a dive; from what I could see they almost always came up with a fish.
The aforementioned humpback whale (Megaptera novaeangliae) was putting on a show this morning for the local humans. I wandered down at about 08:45 on my way to the marine lab. There were about 40 people scattered on the beach and along the side of the road. I settled myself on a rock with my camera and binoculars at hand. It took only a couple of minutes to see this:
Judging by size, this whale appears to be a juvenile. It was swimming just beyond the surf break, where the water was shallow enough that I could see the ripples just beneath the surface as the whale swam by. In this 2-minute video, the whale surfaces to breathe a few times and takes two lunging mouthfuls of fish and water before turning away and heading to slightly deeper water.
If I didn’t have an actual job to do, I could have stayed out there longer, just to keep observing all the action. As it was, my arrival at the marine lab was delayed by about 40 minutes. Oh well. But I didn’t have any time-crucial tasks or meetings this morning so nobody’s schedule was affected except my own, and if I can’t take advantage of serendipitous sightings like this then what’s the point of living in paradise?
. . . clam, right? Yes, except in this case the bivalve is not a clam, but a scallop. I was out at the harbor with Brenna again this morning, looking for molluscs for tomorrow’s molluscan diversity lab. Brenna was hunting for slugs, of course, and had drawn up a rope that had been hanging in the water for god knows how long. Neglected ropes like this are the stuff of dreams for people like Brenna and me, as all sorts of animals recruit to and colonize them. Hauling one up is like going on a treasure hunt.
Two of the animals that had attached to the rope were small kelp scallops, Leptopecten latiauratus. The smaller of the two was about the size of my thumbnail and the larger was about 1.5 times that size. Their shell patterns are very beautiful:
But really, you don’t get a feel for how much fun these animals are until you watch them. Scallops are the most animated of the marine bivalves. They have eyes and sensory tentacles along the ventral edge of the mantle, and react strongly to stimuli. They can clap their valves together so quickly that they actually swim. I wasn’t able to make either of mine swim, but did get to watch them for a while.
The whitish object waving around on the left side of the frame is the scallop’s foot. Rock scallops are not permanently attached to surfaces (if they were, they wouldn’t be able to swim!) but they do use the foot to stick. If they find a spot they like, they try to wedge the dorsal, hinged area of the shell into a crevice.
Just like you and me, scallops have bilateral symmetry, complete with left and right sides. Unlike you and me, however, their bodies are laterally flattened and entirely enclosed between the left and right shells. The only parts of the body that extend from between the shells are the foot and the sensory structures on the mantle edge. Leptopecten has many long filament-like sensory tentacles, and brilliant blue eyes.
I thought I’d provoke a reaction by passing my finger over the animal and casting a shadow over it. Nada. But then it closed its shells a couple of times for no reason that I could discern. However, as my graduate advisor Todd Newberry used to say, The Animal Is Always Right™, and what doesn’t seem like anything to me could very well be a threat to a scallop.
And by the way, I did also collect a few slugs and a chiton for tomorrow’s lab. The highlight for me, though, was the scallops. I hope my students are as captivated by these little bivalves as I was!
