Spines on the sixth leg

The tide was low. Not as low as it gets, but low enough to completely expose the Oyster Bay breakwater and a few of the smaller sections of the remains of WWII ships scuttled there 75 years ago, just after WWII. (Story here, "A bit of logging camp history", and here, "Rust in Peace".)

Around the rock breakwater, the rocks deposited in 1950 to partially replace the fleet of derelict ships, a three-quarter century of the strong currents of Georgia Strait, which separates Vancouver Island from the mainland, has built mounds of gravel on the landward side, creating a broad spit colonized by salt-loving pickleweed and silver burweed. The gravel has extended almost back to the land, enclosing the shallow lagoon. (How do the waves bring in fist-sized rocks? They do, in great heaps.)

View from the "inside"

The position of the log, floated into place, shows the usual high tide line. The protected lower sides of the rocks are coated with barnacles and tiny periwinkle snails.

On the "outside", there's only a narrow, sloping ribbon of gravel, then the wide, flat sandy beach, usually underwater. I poked around on this strip, peering into cracks and examining old rusty ship parts.

Part of a bulwark, maybe? Some of the old yellow paint still remains.

Zooming in. Barnacles, green and red algae, and rivets. And snails, but they're hiding.

And zooming in once again.

These are our common acorn barnacles, Balanas glandula. They don't like heavy wave action, but coat the protected side of rocks and the stony shores where the slope is shallow, reducing the pounding action of the waves. (Walking on one of those beaches, even watching where I put my feet, I hear the "crunch, crunch" of tiny barnacle shells, making crab feed. Sorry, guys! If I could fly, I would.)

They grow densely together; once they've settled in, they won't be moving for the rest of their lives (up to 30 years, I've heard, as long as I don't step on them.) So they have to settle within reach of a mate.

The barnacles are sequential hermaphrodites. That is, they have both male and female organs, and in any one mating event, one acts as female, the other as male. The one acting as a male reaches out a penis up to 8 times his body size to reach a neighbour, who acts as a female for this encounter.

Poor photo, 2010. Barnacle with extended penis, looking for a mate.

On the protected side of a nearby rock, I found bigger barnacles:

Giant acorn barnacles surrounded by the smaller species.

One giant, with small acorn, red algae, and periwinkle snails.

The giant acorn barnacles, Balanus nubilus, are easily recognized by size alone. They may be the largest acorn barnacles worldwide, and can grow up to 15 centimetres across. These are smaller; about 5 cm. The little "commons" can grow up to a maximum of half that. But even in a juvenile, the giants are recognizable by the beak-shaped inner shells, the operculum. Underwater, and feeding, they expose a brilliantly coloured inner body, red, orange, or purple. (I've seen mostly reddish-purple ones.)

Of the small acorn barnacles, there are several similar species. Most of ours are B. glandula but I've also seen the thatched barnacle, B. cariosus, and there is one that settles on crab shells, B. hesperius and several others. All very similar, all extremely variable, depending on water currents, erosion, and the effects of crowding; hard to identify. E-FaunaBC describes the problem:

However, it is not safe to rely alone on the sculpture of the cover-plates for identification as there are species with plates that look nearly the same. Therefore, several other characters must be taken into consideration. The number of spines on the middle segment of the sixth leg; the shape of the mouth parts; and the structure of the base of the shell.

In the absence of barnacles waving those sixth legs at me, I'll just be glad that the name "acorn barnacle" applies to all of them.

~~~~~~~~~~~~~

La marea estaba baja. No tan baja como puede llegar a ser, pero suficiente como para dejar el rompeolas de Oyster Bay completamente fuera del agua, además de algunas partes de barcos sumergidos allí hace 75 años, después de la Segunda Guerra Mundial. (La historia, la puedes encontrar aquí, "A bit of logging camp history", y aquí, "Rust in Peace".

Alrededor del rompeolas, rocas depositadas en este sitio en 1950, para reemplazar (en parte) la flota de barcos en ruinas, tres cuartos de siglo de corrientes de agua del Estrecho de Georgia, que corre entre la isla de Vancouver y el continente, ha construido montones de grava en el lado protegido, creando una lengua de tierra donde crecen Salicornia depressa y Ambrosia chamissonis, plantas halófitas. La grava casi llega a tierra firma otra vez, encerrando una lagunita poco honda. (¿Cómo es que las olas llegan a traer piedras del tamaño de mi puño? No sé, pero sí lo logran)

Foto #1: La vista hacia el mar desde el lado interior del rompeolas. El tronco sobre las rocas llegó flotando y marca el nivel normal de la marea alta. Los lados protegidos de las rocas llevan colonias de bálanos y de caracolitos marinos.

En el lado del rompeolas expuesto al mar hay solo un listoncito de grava inclinada, y luego la playa extendida, arenosa, plana, casi siempre sumergida. Este tramo de grava, con sus fierros viejos y rocas agrietadas estaba fuera del agua.

Fotos # 2 a 4: Un pedazo de barco viejo. Parte del costado, tal vez. Acercándonos, vemos bálanos, algas verdes y rojas, los caracolitos, casi escondidos, y remaches.

Estos son nuestros bálanos comunes, Balanus glandula. No les gusta la acción de olas fuertes, y colonizan los lados protegidos de las rocas, y las piedras de playas poco inclinadas, donde las olas entran suavemente. (Caminando en una de esas playas, aunque tengo cuidado donde pongo los pies, oigo el crujir de bálanos apachurrados, convertidos ahora en comida para cangrejos. ¡Lo siento, criaturitas! Si pudiera volar, lo haría.)

Crecen en colonias densas; una vez que se hayan fijado en la roca, no van a estar libres de ir a buscar pareja, y la necesitan tener cerca. Vivirán en este sitio hasta, según me dicen, hasta 30 años.

Los bálanos son hermafroditos secuenciales, es decir, tienen los órganos de ambos sexos y pueden actuar como hembra o como macho en un apareamiento dado. El que actúa como macho extiende su pene a una distancia que llega a ser hasta 8 veces su propio diámetro para buscar su pareja, quien en este momento actúa como hembra.

Foto #5: Una foto un poco borrosa, mostrando un bálano con el pene extendido. 2010

En el lado de una roca encontré bálanos más grandes:

Fotos #6 y 7: Bálanos gigantes, Balanus nubilus rodeados de bálanos comunes.

Estos bálanos gigantes se conocen facilmente por su tamaño; pueden ser los bálanos más grandes de todo el mundo y pueden crecer hasta 15 cm. de diámetro. Estos, en la foto, son juveniles, midiendo como unos 5 cm. Los bálanos comunes que los rodean pueden llegar a lo máximo, a la mitad de esto. Pero aun en un gigante joven, todavía chico, se puede reconocer la especie por el operculo, las placas interiores, que toman la forma de un pico de ave. Abiertos, bajo agua, se ven los colores fuertes del animal escondido; rojo, anaranjado, violeta.

Entre los bálanos pequeños, hay varias especies muy similares, todas muy variables según el sitio, sea con olas más o menos fuertes, sea con menos espacio, o donde haya erosión fuerte. En E-FaunaBC se describe el problema: 

Sin embargo, no se puede con seguridad depender solamente en la forma de las placas cobertores para su identificación ya que hay especies con placas que se ven casi idénticas. Por lo tanto, hay que tomar en cuenta otras características. El número de espinas en el segmento central de la pata sexta; la forma de las partes bucales; la estructura de la base de la concha.

Yo, no viendo balanitos enseñandome sus patas sextas, me conformo con que el mismo nombre, "bálanos bellota" se aplica a todos. Hasta a los gigantes; Bálanos bellota gigantes.

Barnacle spirit

You never know what to expect in a tank full of critters. I was watching barnacles catching dinner, when one, or rather its ghost, came out into the open.

Thatched acorn barnacle. In life, the cirri are black.

It swayed in the current for a few minutes, then the rest of the body bubbled out.

The long, thick appendage is the barnacle's penis. When the barnacle is searching for a mate, it extends to 8 times the body length. An obvious solution to the problem of being glued in place.

Soon, the entire body floated free. Before a hermit or crab caught it, I fished it out and photographed it on a wet black background.

The long cirri (feathery tentacles) are the legs the barnacle fishes with. I'm not sure of the function of those shorter feathers. Near the base of the penis, the ridging is visible. Muscle tissue, maybe?

Another view, showing the entire body. The head end is on the left; in life, it stays cemented to the floor of the barnacle casing.

Doing things backwards

I bought myself some camera goodies today; my belated selfie birthday present. A new lens, a Nikon Micro 60 mm. A flash to replace a good one I had that got lost. And an expensive - 2 whole bucks at the dollar store - reflecting screen/foam poster board.

I got home with it all, dropped the whole works on the kitchen table, unpacked the lens and attached it to the camera, and took a couple dozen sample shots, hand-held.

The instructions, which I read later, said to always use this lens with a tripod, but I was too impatient to take the couple of minutes to set it up. And I wiped down the outside of my tank, first, but left the inside as is; after all, I'd scrubbed it well yesterday. So of course, there's a new algae scum fuzzing up the glass. And all the photos are noisy, as a result.

I'm still happy. Even under those conditions, the lens performed better than the 40 mm on its best behaviour.

A few samples: I've done minimal processing on these; cropping, despeckling, reducing noise. And eliminating a few inconvenient copepods.

"Hail, fellow, well met!"

Hideaways.

This is not a great shot, but it would have been absolutely impossible with the other lens, even with the tripod and the lighting set up just right. This was a dark corner, in the back of the tank, with only a glimpse between waving eelgrass blades. The crab was just barely visible, and I hadn't even noticed the arm of the starfish in the clamshell. The backdrop is a rotting, ancient abalone shell.

Did I say I'm happy?

Happy, or at least hopeful, barnacle and his penis.

Peaches and the eelgrass ghost.

Balancing act. Tiny hermit on the knife edge of an old clamshell.

Apart from the noise, this lens cleans up the backgrounds considerably. Since the depth of field is so small, everything in back is blurred and blended together. In a busy tank, where I can't really control where my critters are going to pose, that's a real benefit.

I haven't unpacked the flash yet. That's tomorrow's treat. And then I'll set up the tripod and "reflector" and clean the glass properly, and take some more sample shots.

And there's a manual to read for the flash; it looks complicated. Every new model has to have more rabbits in hats and pigeons up sleeves, and it takes some doing to find them all and get them to behave. I'll be busy for a while.

Striped leggings and red, red lips

... Barnacle outfits, that is.

Acorn barnacles on a stone, feeding. The inside of the shell is a deep red.

Long, pale legs, and shorter dark green legs. Another barnacle in the background, smiling.

A barnacle has 6 pairs of legs, putting them between the decapod crabs and shrimp, and the 14-legged isopods. They should really be called "dodecapods" (from the Greek δώδεκα dōdeka "twelve" + ποδός "foot"), although we usually forget that those waving fans are actually feet, modified into feathery cirri, to capture food and absorb oxygen from the water.

And then there is the thirteenth appendage:

The same barnacles. One on the lower right is starting to extend his long penis. It's hairy, too, but not striped.

Each barnacle is hermaphroditic, which is handy, because they can't wander about in search of a suitable mate. Any other barnacle will do, as long as it is within reach of that long, extensible penis.

Never trust a barnacle ...

... to behave with decorum.

I wanted photos of feeding barnacles. Hard to get without a hair-trigger finger and a fast camera, but I've collected a few. Three seemed passable, and I set about editing them.

I got more than I bargained for.

One barnacle feeding

Four barnacles feeding. And a stubby isopod.

Amorous barnacle, reaching out his penis, looking for a mate.

In the blurry sections of the uncropped second photo, a mass of barnacles, there were several others also waving penises about.

The last photo was taken in the beginning of January, last year. Acorn barnacles need cold water to breed, so they start mating in November or December. Each barnacle is hermaphroditic, which is handy, because they can't wander about in search of a suitable mate. Any other barnacle will do, as long as it is within reach of that long, extensible penis. In the photo above, it reaches down past the snail, down to the bottom of the photo. The next barnacle was a bit further away, but this guy could still stretch a ways, up to 10 times his body length.

Links:
About barnacle penises. From BoingBoing
More. From Southern Fried Science
And general barnacle information, from BBC

Unlucky in love

Barnacles have a problem. They have settled for a peaceful, uneventful life; except for a brief period of freedom as young Nauplii, they are entirely sedentary. They glue themselves to a likely-looking foundation; a rock, a shell, a larger animal, a boat or sunken trash; build a home, and never leave it again. With their heads firmly hidden away from the larger world, they wave their hind legs in the water, fanning edibles towards their mouths.

Depending on their choice of homestead, this works out pretty well for them; the castles they have built for themselves are roomy, the walls strong and easily locked down in case of enemies. But, opting for security in place of freedom, they have sacrificed choice.* If the area becomes polluted, or if food is scarce, they have to put up with it. If they have chosen a mobile base, such as a crab shell or a ship, they are at the mercy of the whims of their transport, or condemned to its fate, if it dies.

Some of the barnacles in my aquarium were lucky, sort of. They attached themselves to a crab, which died and was cast up on the beach. Many of their companions died, too, exposed to the chill, dry air. But I rescued a few and added them to my nice, nutrient-rich tank. Ahhh! Except that the tank also houses three trophon snails, hungry barnacle eaters. And a few shore crabs, which also appreciate a nibble of barnacle flesh, and even more often, flip the chunks of crab shell upside down, leaving the barnacles out of the current, combing through sand like a snail.

Every day, when I feed my critters, I flip upside-down barnacles over with a chopstick and they begin fanning again.

Crenate barnacle, feeding, while hermit crab looks on.

There's another aspect to this problem; finding mates. They can't go in search of one, and the mate is likewise cemented to a rock. Maybe it's close by; barnacles usually live in tightly-packed communities. But often they are separated by the movement of their base, or by predation.

There are a variety of strategies to overcome this; some sessile (non-moving) animals just dump sperm out into the water, in the hopes that it will find a receptive female. (Corals, for example.) Others simply clone themselves; the aggregating anemone is one of these, at least sometimes.

The barnacle has another approach; he has the longest penis for body size of any member of the entire animal kingdom. Depending on the currents, it may reach to 8 (or 10) times his body length. The tip is prehensile; when he finds another barnacle, he inserts it and fertilizes her. Since barnacles are hermaphroditic, with both male and female organs, he need not look further than the closest receptive neighbour.

This is what I saw in the early hours of Christmas Eve; one of the barnacles was looking for a mate. For about 10 minutes, I watched as he extended his penis parallel to the sand, waving it about slowly, exploring. At the farthest reach, he was searching about 4 times his body length away.

A bad location for a lovelorn barnacle.

Unfortunately, the barnacles closest to him were shut down tight, probably because the trophon snail was busy eating his neighbour. The next few were just a bit too far away; maybe he would have gotten there in time, but a hermit came along and rolled him over. Back to chewing sand!

In this photo, the penis is barely visible, as a smooth tube. The feeding cirri are feathered and clustered around the mouth of the shell.  There is a clearer photo, and more information, at BogLeech.  NewScientist has an interesting article about the effect of current on penis length. Wikipedia contributes information on predators and competition. The life cycle is described on MESA. (And my previously-posted photo is here.)

*This is not a parable; it's the way things work.