I recently got to be a part of an abalone spawning team, where we induced abalones to release their gametes. It was very fun to see the fertilized eggs develop, and interesting for me because it was the first time that I had actually seen spiral cleavage in action! It was so different looking than radial cleavage...
I did not manage to get pictures of all of the stages, as I had to sleep, so expect some gaps. But I hope you enjoy this abalone development slide show that I put together of the stages I did see.
We got a new addition last week, a Carinaria japonica an unusual animal commonly called a sea elephant, after its long snout-like proboscis. It is generally around 13 cm (5 in) but can get to 50 cm (20 in) long. This one is about 30 cm (12 in). This animal is a type of snail, called a heteropod, that is modified to spend its entire life swimming in the water column.
Its shell is very reduced, to decrease the weight on the animal, and located on the bottom of the creature. Because of the shell's weight, small that it is, the animal spends its life swimming 'upside down'. The flap that it uses to swim with is a modified foot, and it has a large radula at the end of its proboscis for capturing prey.
It has very well developed eyes for a snail, complete with spherical lenses and ciliated retinas. The retinas themselves are interesting, because they are a thin strip, rather that a large patch. Because of that its vision field is only a few degrees high, and 80 to 180 degrees long [1]. Some species solve that problem by constantly sweeping their eyes up and down.
They eat other things in the plankton, preferring things like arrow worms, salps, copepods, and krill [2]. The prey is ingested whole, and digestion generally takes place without any mastication. There really is not much known on how they capture their prey, and I'd like to make a few comments based on observations made while feeding this little guy.
I have been feeding him by hand, which is certainly not natural, but I have noticed that when I drop food or put food near him, he cannot capture it without some sort of pressure behind it. The jaws of the radula seem to push out, then open, clamp the food then drag it back in. If there is no pressure behind the food, the radula just pushes it away. He generally solves the pressure problem by maneuvering his proboscis so that the food is trapped between it and the wall of the tank.
Obviously, that trick would not work in the wild, but I have noticed a second trick which would work in the wild. With floating food, he sometimes curls in to a circle and traps it between his proboscis and his large broad tail. This may be a behavior which helps them capture food in the wild... we won't know for certain until someone seriously takes a look at that.
In the meantime, I will continue to observe and marvel at my new companion...
I guess all larval animals have a clear, frosted appearance, but I choose this particular larva because it's special to me. This is a veliger larva, a larval stage which is typical to the marine snails. In particular, this is a baby lion nudibranch, Melibe leonina. This larva hatched today, and I am trying to rear them to adulthood.
The fuzzy bits toward the bottom of the veliger is cilia, which helps it swim. The two round dots that look like eyes are actually statocysts, which help the larva figure out orientation (up and down). These guys have a thin shell in the veliger stage, which they lose when they metamorphose into juveniles.
Adult lion nudibranchs live in the kelp canopy, and eat small creatures that live on the kelp or float by. They use their big oral hood much in the same way a Venus fly trap catches flies. Because of the way they feed, they are one of the easiest sea slugs to keep in a public aquarium. They are also one of the few sea slugs to swim.
It will take a little over month before these little veligers metamorphose and settle into the adult form. It will be a welcome challenge to try and keep some of them alive for that long.
Here we have an amazing picture of a Banana slug (Ariolimax sp.), which I captured a photo of it as it roamed across the forest floor in Muir Woods. There are three species of Banana slug known, one of which, Ariolimax columbianus, is the second largest terrestrial slug in the world. It can reach up to 25 cm (10 in) long. All live in the foggy, forest belt on the pacific coast from Central California to Southern Alaska.
These guys posses a pneumostome, a hole which is visible in this picture as a dimple a bit down from the head. The pneumostome opens into a highly vascularized cavity which acts as a simple lung for these animals.
They are very prone to dehydration, so tend to inhabit areas that are moist, and produce lots of mucus. At the tail end of the slug, you can see some debris caught in the slug's mucus plug. This plug covers the caudal pit, where the mucus is produced. Their mucus not only keeps them moist, and helps them move, but also protects them as it has an anesthetic-like chemical making them unappetizing to other creatures.
Finally, Banana slugs also use their mucus as a mode of communication. During mating season, they will incorporate pheromones into their mucus, making it easier for another slug to find them.
This is a very rare animal, the white abalone (Haliotis sorenseni). They used to be found in great abundance in the subtidal waters off California (80 to 200 ft), there are now less than 3,000 individuals remaining in the wild. This is an issue as these animals are broadcast spawners, that is they release eggs or sperm into the water column to be fertilized. If there are no other individuals nearby, then the eggs will not be fertilized. Because of the low population numbers and their reproductive strategy, these animals are considered reproductively extinct.
However, they are on the list of endangered species, giving them great protection in their natural habitat. There are also some efforts underway to breed these snails in captivity to restock the wild populations. Work is slow, as it takes time for them to grow, and as growing them in farms leads to the increased risk of transporting diseases from the farm to the wild.
Whenever I am in the intertidal, I love looking for the small hidden things. This is a close up of a limpet, most likely Lottia digitalis, hidden in a gooseneck barnacle cluster. Amazingly, these limpets can change their shell shape and color based on what they are resting on.
Limpets which hang out on gooseneck barnacles get lines on their shells that look like the lines on the barnacle. They also have a higher domed shell. Rock morphs are less patterned with a lower shell. This one does not seem to have too much cryptic coloration, but the shell is really worn. Supposedly, the change between these two morphologies is partly because of the change in algal diets in the two areas [1].
This little two-spot octopus was only about 2 months old when the picture was taken. He (or she) would be able to fit into VERY narrow spaces, as the only hard part on its body is its beak. An adult two-spot octopus can get up to three feet in length (arm to arm), and has a beak about the size of you pinkie fingernail. This little guy was almost an inch (arm to arm), so I can't even imagine how small its beak is. But I do know that it fit into the most amazingly small spaces to enact its escapes.
This little octo is still going strong at the aquarium, and is about 6 months old at this point. We have had some success in feeding it, even though its diet constantly changes as it grows. Its about 2.5 inches from arm to arm now. Hopefully, we will be able to raise it to adulthood.
This is a black dorid (Polycera atra) that I caught feeding on some bryozoans I collected for my thesis. I have caught at least four different species of nudibranch (sea slugs) as I am collecting their main food source, but I think this one is my favorite for its coloration. These nudibranchs tend to e a little toxic, as they concentrate the toxins from their food source in their tissues, so the beautiful patterns are used to warn off would-be predators. Some nudibranchs take a different route, and use their coloration to blend in with their food source so well, it is hard to see them even when you look very closely.
This may have slipped under people's radar, so I thought I'd put up a quick post. In February, the black abalone will be put on the endangered species list. It joins the white abalone and 2 species of coral as the only invertebrates on the list.
In some ways this is a major win, as now the abalone will get the protection it desperately needs. In other ways, it is always a major loss when a species gets to the point were it needs to be on the list. The white abalone, (the other mollusk on the list) is basically considered reproductively extinct. They are very hard to rear in captivity, so no real progress has been made in raising and re-introducing them to the wild. I don't know if black abalone are similar to whites, or if they are more like reds, which are much easier to rear. So much easier to rear that they are often farmed.
One can only hope that there will be some way to restore the black abalone to the tidepools.
This is a picture of Kellet's whelk, Kelletia kelletii, snacking on some fish for breakfast. Kellet's whelks are one of the larger gastropods (snails) found on the California coast. They generally tend to scavenge on dead or dying animals, but have also been know to eat crabs and lobsters caught in traps. They use their long, prehensile proboscis to reach into the traps, or in this case holes on top of the plexiglass container, and use the radula at the tip to scrap off flesh or drill through shells.
Mussels can be a dominate organism in many rocky intertidal communities. Unlike other permanent residents, like barnacles and algae that are permanently attached to the rocks, mussels can move short distances by creating byssal threads. The byssal threads are primarily used as a means of attachment, but by creating and attaching new byssal threads and cutting lose from old ones, mussels can pull themselves along rocky shores.
People who walk around in the intertidal may notice, like the authors of a cool article featured in Science, that mussels often cluster in interesting patterns on the rocks. The authors found that the size of the clusters and the pattern of the clusters is consistent among mussel beds (with similar mussel densities), set out to determine why.
They found that if you spread mussels out evenly in the laboratory, they will spontaneously form clusters similar to those seen in the field, even in the absence of the rocky substratum and wave action found in the field. They also found that if you place mussels in various-sized clusters at the start, there is a difference in movement based on initial cluster size. Mussels in small clusters (with 2-8 individuals) and mussels in large clusters (with 128 individuals) tended to move around and rearrange themselves a lot more than medium size clusters. So, mussels really want to be in a cluster of a certain size... but why?
Large clusters have may have a food limitation. With all of their neighbors filter feeding, having to many individuals around you may limit the amount of food you can capture. When the authors squirted food in the middle of large clusters, the individual mussels were pretty content to stay in the large cluster. But if clustering reduces food, why cluster? When placed back out in the field, individuals who were not in a cluster were more likely to be knocked off by wave action.
So, individual mussel will gather together in a cluster, but when the neighborhood gets too crowded they move. By arranging themselves in the rather interesting maze-like pattern of clusters and spaces often seen in the intertidal, individuals get protection from wave action, and have a higher growth rate than densely-packed mussel beds.
Van de Koppel, J., J. Gascoigne, G. Theraulaz, M. Rietkerk, M. Mooij, and P. Herman. 2008. Experimental evidence for spatial self-organization and its emergent effects in mussel bed ecosystems. Science. 322:739-742.
I recently went on a collecting trip up the coast, and there were hundreds of these sea slugs wandering around on the mud flats we were at. They are really small (my hand is the background in the picture), and the trip leader could not identify them. I took a quick picture and they took a egg mass back with them, to try and ID these slugs. I asked a friend who works with sea slugs and she tentatively identified them as an Aplysiopsis species. Interestingly, she had gone on a trip farther north, and seen hundreds of these as well. So they seemed to be blooming all along the central/northern part of the coast.
Alas, we won't truly know what species it is unless we look at its radula and penis, two of the main features used to distinguish different sea slugs. But this little adventure has allowed me to get some fun footage of mystery slug veliger larvae! This larval type is characteristic of gastropods, and if you look at them you will notice that as larvae, they all have shells. The shell is lost in the adult sea slug.
Another super cute baby octopus picture! They seem to be pretty healthy looking, and have the strength/ cunning to escape their enclosures. So far, I've returned two to their tanks after they have escaped to the wet table. One of them even caught its first meal the other day. (We fed it a small grass shrimp) Hopefully, they will survive to adulthood.
This is the nudibrach Hermissenda crassicornis. While it may not look like much, when I look at it, I think 'smart'. H. crassicornis has often been used as a model animal as it is a great thing to study if you want to learn how memories are formed. They have a very simple nervous system, simplified to the point where every neuron has been mapped and named. Additionally, they can be conditioned to respond in certain ways when presented with a stimulus (much like Pavolv's dogs). Put that together with the ability to follow impulse along the nervous system, and you can 'see' how the slug reacts normally to a stimulus, then see how the route changes after you condition them. They've actually found out where memories are stored in these guys! If you want to learn more about learning check out Blackwell, 2006 for a review on the subject.
This is a purple-ringed top snail, Calliostoma annulatum, the most beautiful shelled snail on the west coast in my opinion. They cruise up and down kelp plants looking for a meal. Generally, they eat what ever is growing on the kelp plants, such as hydriods, bryozoans, diatoms, and copepods. If there is nothing on the kelp plant, they will eat the kelp itself. They have been known to travel 20-30 feet in a twenty-four hour period.
This is most likely a rock scallop (Crassadoma gigantea), although it is unusual to find them lying loose like this at this size. They are free living until about 2 inches, when they attach to the substratum [1]. They then cement their right valve to something and they grow to fit the contours of what they attached to.
You can see the concentric rings of the gills on the inside, which they use to filter feed, and the small black dots on the outer ring of the orange mantle are the eyes. Of all of the molluscs, scallops have the most developed eye structure [2]. Most other molluscs posses pigment cups or eye spots. The scallop's eye is composed of a lens, two retinas (the distal retina, which faces towards the light, and the proximal retina, which faces away from the light source), and a reflective tapetum layer, which often gives scallop eyes a blue sheen. These eyes are most often used to detect changes in light levels, allowing free living scallops to escape when a potential predator passes.
This is navanax, most likely Navanax inermis. As part of the opistobranch subclass, these have a reduced internalized shell. They are voracious predatory slugs which generally inhabit eelgrass beds and mudflats. They track other opistobranchs (like bubble snails) through the mudflats by following their mucus trail. When they catch up with their prey, they swallow them whole. After the snail has been digested, they excrete the whole empty shell. When disturbed, navanax produces a yellowish fluid which alerts other navanaxs to danger.
This is Hopkin's rose (Okeniarosacea) a doridnudibranch. Even though it possesses tall papillae like the aeolidnudibranchs, you can see that it does have an external gill plume, which places it firmly with the dorids.
These nudibranchs lack oral tentacles, but do possess rhinophores, which you can just see sticking up out of it's head. They also have an interesting smooth hook on theirradular teeth which lead them to have their own genus for a while. However, recent phylogenetic work using several morphological characteristics, shows them to be a monophyletic group within the Okenia genus (Gosliner, 2004).
They feed upon a bright pink bryozoan, Integripeltabilabiata, which is where O. rosacea gets its rosy color from.
This a picture of a dorid nudibranch (Doridella steinbergae) and a bryozoan (Membranipora). Can you tell which is which?
The bryozoan is an encrusting animal that generally lives on kelps and also green algae. There is some debate as to if Membranipora is harmful to the kelp, but in general it is thought is can block the absorption of nutrients because it grows over the kelp.
Doridella is one of the few predators of Membranipora and is camouflaged to blend in with its prey. Normally, dorid nudibranchs have a circle of gills visible on their back, but Doridella’s gills are located behind the foot under a flap of skin. This helps them blend in better with the bryozoan. They feed on Membranipora by creating a suction seal, using their rasping tongue (called a radula) to cut through the outer membrane, then they suck out the insides.
Membranipora can create spines in response to predation by Doridella. Just put Membranipora in some seawater that has the nudibranch’s chemical cues in it, and it will make spines to protect itself from attack.
So did you find Doridella?
The two bumps on the top right are Doridella’s rhinophores, used for chemoreception. Only nudibranchs have rhinophores, so that’s the tip off.
I am a student of Marine Biology, just finished up my masters and no longer contemplating continuing on... I AM continuing on! Most of my clothes are salt stained and my personal philosophy is ‘Spineless is splendid’.
Kingdom: 
