Tag: marine biology

Branching out

Posted on by Allison J. Gong

Today I decided to look at some scuzz growing in one of the seawater tables at the marine lab. This table is populated mostly by coralline rocks, although I have some pet chitons running around in it.

Coralline rocks in seawater table at Long Marine Lab, 16 June 2015. © Allison J. Gong
Coralline rocks in seawater table at Long Marine Lab
16 June 2015
© Allison J. Gong

I picked out a promising rock and examined it under some decent light. Most of the rocks have at least some fuzzy red filamentous algae growing on them; this one also had a bit of a filamentous green, which made it a promising subject for photography. I already knew what the green was (Bryopsis corticulans) but didn’t recognize the filamentous red. The Bryopsis is in the lower right corner of the rock in the photo below:

Coralline rock bearing red and green filamentous algae, 16 June 2015. © Allison J. Gong
Coralline rock bearing red and green filamentous algae
16 June 2015
© Allison J. Gong

What was noticeable about the Bryopsis and the mystery red is the difference in size. Bryopsis looks positively dainty until you compare it with the red. Wanting to take a closer look at the red, I plucked off a bit and mounted it on a microscope slide. This is really the only way to see what’s going on with these filamentous algae, and it works like a charm. You don’t have to make a cross-section or anything; you just put the piece in a drop of water, add a cover slip, and look at what you can get:

Apical tip of Antithamnion defectum, 16 June 2015. © Allison J. Gong
Apical tip of Antithamnion defectum
16 June 2015
© Allison J. Gong

What first caught my eye was the rather simple branching pattern. The central axis is made up of roughly rectangular cells, each of which has two side branches that are opposite each other. Each of the side branches has branchlets on only the upper surface. Branching like this is relatively easy to draw (things spiralling around in three dimensions are really difficult for me), although my drawing isn’t nearly as pretty as the real thing.

This microscope view, along with my little sketches, provided me with enough information to key out this alga even though it didn’t have any reproductive structures. According to the dichotomous keys in Marine Algae of California* (the book that marine biologists refer to as the MAC, our Bible for identifying the algae) it is Antithamnion defectum. The MAC says that this species is common on other algae and can be found both intertidally and subtidally from southern British Columbia to Baja California. It could very well be that I see this species in the field, but these filamentous reds look pretty much the same, at least to my inexpert eye. It really does take a microscope to figure out what I’m looking at.

*Abbott, Isabella A. and George J. Hollenberg. Marine Algae of California. Stanford: Stanford University Press, 1976. Print.

Green is the new sexy, Part II

Posted on by Allison J. Gong

Part of what makes the marine algae so fascinating to me is their life cycles. I’m intrigued by organisms that do things differently from us. And to be honest, from the perspective of someone who studies invertebrates and their life cycles, we humans are rather boring: we’re born into in one body, reproduce (maybe), and then die, all in the same body. Ulva, on the other hand, follows the typical plant example and has a life cycle that includes alternation of generations.

Without going into too much detail, let’s just say that Ulva has two generations within a single life cycle, one called a sporophyte and the other called a gametophyte. The difference between the sporophyte and gametophyte is the number of chromosome sets found in the cells of the respective generations: sporophytes have two sets of chromosomes per cell, a condition which we describe as being diploid (2n), while gametophytes are haploid (1n) and have only one set of chromosomes per cell. The diagram below lays it out nicely. Note that the gametophyte in the diagram is white, while the sporophyte is green.

Alternation_of_generations_simpler.svg

The little white circles in the diagram above are the reproductive cells. These cells are produced by either the gametophyte (in the case of gametes) or the sporophyte (in the case of spores).

Now, determining if what you’re looking at is a sporophyte or gametophyte can be easy or difficult, depending on whether your species is isomorphic (‘same form’) or heteromorphic (‘other’ or ‘different form’). Unfortunately for us, Ulva happens to be isomorphic, which means that the sporophyte and gametophyte are for the most part morphologically indistinguishable. However, if you knew what kind of reproductive cells a particular generation produces, you could deduce whether that generation is a sporophyte or a gametophyte, right? So, is there any way to determine whether a 2.5 µm cell is a spore or a gamete?

Yes, there is! In the group of algae that includes Ulva the spores are quadriflagellate, which is just a fancy way of saying that each one bears four flagella. The gametes are biflagellate, having (you guessed it) two flagella. Now it’s just a matter of counting flagella on these tiny reproductive cells released by the specimen of Ulva in my bowl.

And voilà!

Biflagellated gametes of Ulva sp., 11 June 2015. © Allison J. Gong
Biflagellated gametes of Ulva sp.
11 June 2015
© Allison J. Gong

It’s clear that these cells have only two flagella, right? This means that they are gametes, not spores, and the thallus that produced them was the gametophyte!

Pretty dang nifty, isn’t it?

Green is the new sexy, Part I

Posted on by Allison J. Gong

I was making my last run through the wet lab today, about to head off to forage for lunch before a meeting elsewhere, when I saw this in one of my bowls:

Specimen of Ulva sp. spawning, 11 June 2015. © Allison J. Gong
Specimen of Ulva sp. spawning
11 June 2015
© Allison J. Gong

This is one of my feeding treatments for the juvenile urchins. The sheet of green stuff is Ulva sp., a green alga several species of which grow locally in the intertidal. You also see it in harbors and estuaries. This particular bit was growing ferally in one of the large outdoor tanks in an area of the marine lab called the tank farm.

You can see that the algal body (called a thallus) has a fairly distinct edge, except for the parts that the urchins have munched through. Can you also see the cloudy pale green water that runs sort of horizontally across the middle third of the bowl? That’s the stuff that caught my eye. After glancing at the clock I figured I had just enough time to take a quick peek under the scope, and if I really didn’t care about eating lunch I could even snap a few pictures and still make it to my meeting on time. Anyone who knows me personally understands that I organize my life around food and the next time I get to eat. The fact that I was willing to forego lunch to look at this green spooge should tell you how exciting this was.

(It turns out that a few minutes later the person I was supposed to meet with e-mailed me and asked to postpone our meeting until next week. Yes! This means actual quality time with the microscope and the spooge.)

Here’s what a spawning green alga looks like:

That undulating column on the left side is a stream of reproductive cells being released by the thallus. And yes, those are my little urchins chowing down. They like eating Ulva much better than the coralline rocks they’d been subsisting on until recently.

Under the compound scope at 400X magnification, the reproductive cells look like this:

The tiny little cells zooming around are about 2.5 µm long. The way they swim suggests that they have flagella. Do they look familiar?

They should. They look a lot your typical flagellated animal sperms! I don’t think it’s a coincidence that my first thought upon seeing the green stuff in the bowl was “Spooge!”

But here’s where it gets tricky. For algae, looking and acting like sperm doesn’t mean that something is sperm. More on that in the next post.

Questions and answers

Posted on by Allison J. Gong

I’ve been fielding questions about my recent sea star spawning work from people I’ve shared this blog with, which is a lot of fun! To streamline things and make the info available to anybody who might be following, I decided to put together a very brief FAQ-like post to address the most recent questions.

Question:  Can you watch the eggs divide in real time?

In a time-lapse sense you can watch cleavage divisions occur, but not in real time. What I can do is set up a slide on the microscope and leave it there for a while. The gradually warming temperature speeds up development to the point that I can sort of see the division in real time. Of course, the danger is that the embryo will cook on the slide. I generally figure that once I’ve pipetted some embryos onto a slide and dropped a cover slip on top of them, they’re goners (it’s not really possible to remove the cover slip without damaging the cells underneath it) so I feel marginally less bad about sacrificing a few to the gods of observation.

Questions:  I’m fairly certain that the stars can go back to the sea, but are you able to keep their eggs with them, too? How difficult is that transport?

Actually, my scientific collecting permit specifically states that I’m not allowed to return animals to the wild. If I needed to, I could apply for additional permits but it has never been necessary for the work I do. Surplus eggs and larvae, therefore, are discharged into the seawater outflow at the lab and do return to the ocean but the parents remain in my care.

Question:  Are orange and purple stars usually able to cross with each other?

As far as anyone has been able to determine, the color of stars has zero effect on whether two individuals’ gametes are able to do the nasty together. The sea stars that I’m working with–Pisaster ochraceus, the ochre star–are broadcast spawners, meaning that each individual spews his/her gametes into the water, where fertilization and development occur. The stars are also synchronous spawners, meaning that if one individual in an area begins spawning other stars in the immediate vicinity will also spawn. After all, it does take two to tango, and to spawn while nobody else does is a tremendous waste of energy.

So yes, a purple star and an orange star should be able to mate without any problems… at least not any problems due to the parents’ colors.

Question:  If so, what color do they end up being, statstically?

This is a very interesting question. Two of my colleagues are going to spawn Patiria miniata (bat stars) next week to address this. Their plans are to cross a Blue female with an Orange male, an Orange female with a Blue male, and both pure-color matings. They did a preliminary version of this experiment a couple of years ago but didn’t end up with enough juveniles at a size that color could be ascertained; thus they couldn’t calculate any statistically meaningful color ratios.

Questions:  Do you suppose that the wasting disease could be now in the genetic makeup? Any thoughts (unofficial of course) about this?

My thought is sort of the opposite, actually. The animals that we brought in from the field are all survivors of SSWS; if anything, I’d expect them to be resistant to whatever causes the plague, and to (hopefully) pass on this resistance to their offspring. Of course, there’s no way of knowing if and how exposure to SSWS affects the quality of the gametes. It’s quite possible that these survivors are less fit after the SSWS outbreak than they were before.

Question:  Purple Male with Purple Female developed well and purple Male with Orange female didn’t…some sort of incompatibility?

Well, given what I saw today the Orange (female) x Purple (male) cross almost certainly did not work. Fertilization occurred, but almost none of the embryos had any indication of normal development. Since we know the Purple male was able to mate successfully with the Purple female, we can infer that his sperm were fine. It could be that there was something going on with the Orange female’s eggs; there were a lot of them, but maybe their quality just wasn’t very good. Or perhaps we somehow mistreated and wrecked them the other day.

Any other questions? Use the Comments section to ask them, and I’ll address them in a future post.

From zero to cleavage in. . . nine hours

Posted on by Allison J. Gong

A recent college graduate and fellow marine lab denizen (Scott) and I are collaborating on a project to quantify growth rates in juvenile Pisaster orchraceus stars. This is one of the intertidal species whose populations in the field and in the lab were decimated by the most recent outbreak of sea star wasting syndrome (SSWS). We are interested in seeing how quickly the stars grow once they metamorphose and recruit to the benthos, and hope that the information will help researchers guesstimate the age of the little stars that are now being seen in the field. This would in turn tell us whether the little stars are survivors of SSWS or post-plague recruits. I keep seeing people refer to them as “babies,” but they could very well be several years old. We just don’t know, hence this study.

Large, healthy specimen of Pisaster ochraceus at Davenport Landing. 20 May 2015. © Allison J. Gong
Large, healthy specimen of Pisaster ochraceus at Davenport Landing
20 May 2015
© Allison J. Gong

But before we get to measure juvenile growth we have to get through larval development, which is perfectly fine by me because I’m always up for observing marine invertebrate larvae. Two weeks ago Scott and I ventured into the field in search of prospective parents. We brought back eight individuals from two different sites, making sure to leave many more in place than we took away. It was actually rather gratifying to see how many hand-sized-or-larger P. ochraceus there were. This morning we met at 07:30 to shoot up the stars with magic juice and then wait for them to spawn.

We have injected the stars (Pisaster ochraceus) and are waiting for them to spawn. 2 June 2015 © Allison J. Gong
We have injected the stars (Pisaster ochraceus) and are waiting for them to spawn
2 June 2015
© Allison J. Gong

It has been a while since I tried to induce spawning in Pisaster, and I had forgotten how much longer everything takes compared to the urchins. For one thing, the magic juice itself isn’t the same stuff that we use on the urchins, and works by an entirely different mechanism. The stars’ response to the magic juice takes 1.5-2 hours, whereas if the urchins aren’t doing anything 30 minutes after getting shot up they either need another injection or simply don’t have gametes to share.

However, despite my misgivings the animals spawned. Two large females gave us enormous quantities of eggs, and three more donated trivial amounts that we didn’t end up using.

This purple individual is the one we designated Female 1. See the huge piles of salmon-pink eggs?

Large purple female Pisaster ochraceus, spawning. 2 June 2015 © Allison J. Gong
Large purple female Pisaster ochraceus, spawning
2 June 2015
© Allison J. Gong

and

Large orange female Pisaster ochraceus, spawning. 2 June 2015 © Allison J. Gong
Female 2, a large Pisaster ochraceus, spawning
2 June 2015
© Allison J. Gong

Although we had to wait for a male to spawn, we finally did get some sperm and fertilized the eggs at about 12:30. Another thing I had forgotten was that Pisaster eggs, when shed, are lumpy and strange. I was used to the urchin eggs, which are usually almost all beautifully spherical and small. The stars’ eggs are about twice as big, at ~160 µm in diameter. The lumpiness doesn’t seem to hamper the fertilization process, as you can see below.

Fertilized eggs of Pisaster ochraceus, 2 June 2015 © Allison J. Gong
Fertilized eggs of Pisaster ochraceus
2 June 2015
© Allison J. Gong

In this photo you can see the fertilization envelope surrounding most of the eggs. In stars the perivitelline space (the space between the egg surface and the fertilization envelope) is very narrow, which makes it difficult to see the envelope; in urchins the space is much larger, and as a result the envelope quite conspicuous. The rising of the fertilization envelope off the surface of the egg is referred to as the slow block to polyspermy, a mechanical barrier that keeps multiple sperms from penetrating any individual egg. There’s also a fast block to polyspermy, but it happens on a molecular level milliseconds after a sperm makes contact with the egg surface; you can’t see it happen in real time.

Cleavage in stars proceeds much more slowly than it does in urchins, too. In embryological terms, “cleavage” refers to the first several divisions of the zygote, during which the cell number increases as the cell size decreases. This inverse relationship between cell size and number logically has to occur because the embryo can’t get any larger until it has a mouth and begins to feed, which won’t happen for at least a couple of days. It took our zygotes about four hours to undergo the first cleavage division.

2-cell embryo of Pisaster ochraceus, 2 June 2015 © Allison J. Gong
2-cell embryo of Pisaster ochraceus
2 June 2015
© Allison J. Gong

I left the slide on the microscope to warm up and speed development a bit, and about 45 minutes later was rewarded with this mishmash of embryos at different stages. Nine hours after we started this whole process, there were 2-cell, 4-cell, and 8-cell embryos, as well as eggs that had not divided yet.

Embryos of Pisaster ochraceus, about four hours post-fertilization. 2 June 2015 © Allison J. Gong
Embryos of Pisaster ochraceus, about four hours post-fertilization
2 June 2015
© Allison J. Gong

This asynchrony in early development is another way that stars differ from urchins, and it takes some getting used to. I expect that development will become more synchronized as the embryos continue to cleave, and that hatching will occur for all of them at about the same time, probably before Thursday. At least it won’t take another 9-hour day to see how far they’ve come.

Sea urchins have no manners

Posted on by Allison J. Gong

On Monday of this week (today is Thursday) I was transferring my baby urchins into clean bowls as I always do on Mondays, and for some crazy reason decided that I needed to measure all 300+ of them. I don’t remember how the details of how this decision came about, but it probably went something like this:

  • Me #1:  You know, we should probably measure these guys. We do want to see how fast they’re growing, after all.
  • Me #2:  Are you kidding? Do you know how long it’s going to take to measure 300 urchins under the microscope? We don’t have that kind of time today!
  • Me #1:  Oh, come on, don’t be so lazy. How long can it take, really? Let’s do it for science!
  • Me #2:  These things always take twice as long as you think they will.
  • Me #1:  It’s not as though you have anything better to do this afternoon. I mean, aside from writing a final exam and grading all those research papers you assigned.

Three-and-a-half hours later, Me #2 was soundly kicking Me #1 in the butt and we were all tired. But the urchins got measured and now I have some baseline data so I can track further growth. And, no, I don’t have the urchins separated into individual containers so I won’t be following individual growth, but will be able to calculate average growth rates across the cohort.

Having to look at each urchin long enough to get it lined up with the ocular micrometer in the dissecting scope gave me a chance to observe how their colors are developing. In the field, urchins of this species (Strongylocentrotus purpuratus) in this size range (mm-3 cm) are usually greenish in color; when these individuals are brought into the lab they turn purple as they continue to grow. I seem to recall that my last batch of lab-grown urchins (in Spring 2012) didn’t go through that green phase as juveniles, at least not as vibrantly as what we see in the field. So while I was holding down the current batch of urchins to measure them, I noted their color.

Some of them have a definite green tinge at the base of the spines, which then fades to a mauve-y purple towards the tips. The green coloration is most evident on the younger spines:

Strongylocentrotus purpuratus juvenile, age 118 days. This individual has a test diameter of 2.7 mm. 18 May 2015. © Allison J. Gong
Strongylocentrotus purpuratus juvenile, age 118 days. This individual has a test diameter of 2.7 mm
18 May 2015
© Allison J. Gong

In addition to giving the urchins something more substantial than scum to eat, having them on coralline rocks gives me a chance to see some of the other critters that live on the rocks. This particular rock is inhabited by a number of spirorbid polychaete worms that build tiny circular tubes made of calcium carbonate, as well as assorted small barnacles cemented to the rock and other crustaceans crawling around.

This is a close-up shot of one of the spirorbid worms. The tube is entirely covered by pink coralline alga, but the worm’s orange tentacular crown and trumpet-shaped operculum (used to close the tube when the worm withdraws) are extended as the worm filter-feeds:

Spirorbid polychaete worm on coralline rock, 18 May 2015. © Allison J. Gong
Spirorbid polychaete worm on coralline rock
18 May 2015
© Allison J. Gong

Another photogenic animal that I happened to find was a very small chiton. By the time I found it after measuring all the urchins I didn’t have the brain energy to try and key it out; if I can find it again once I’ve finished grading final exams I’ll give it a shot. It is extremely cute, with its bright blue spots, and was very slowly creeping around on the rock when one of the urchins barged in and ran right over it:

The chiton is probably about 4 mm long, just a bit longer than the urchin’s test diameter. To the urchin, walking over a chiton isn’t much different from walking over a rock; and while the chiton probably doesn’t like being walked on it isn’t significantly affected by the incident unless the urchin starts gnawing on it. Chitons are the masters of just hunkering down and waiting for things to get better, whether that means the tide coming back or an uncouth urchin moving along and minding its own business.

When is a tube worm not a tube worm?

Posted on by Allison J. Gong

Answer:  When it’s a snail! Yes, there are snails that secrete and live in white calcareous tubes that look very similar to those of serpulid polychaete worms. Here, see for yourself:

Serpula columbiana, a serpulid polychaete worm, at Point Piños, 9 May 2015. © Allison J. Gong
Serpula columbiana, a serpulid polychaete worm, at Point Pinos
9 May 2015
© Allison J. Gong

The worms secrete calcareous tubes that snake over whatever surface they’re attached to. When the worm is relaxed, it extends its delicate pinnate feeding tentacles and uses them to capture small particles to eat; they are what we call suspension feeders.

Serpula columbiana polychaete worms, Seymour Marine Discovery Center, 11 May 2015. © Allison J. Gong
Serpula columbiana polychaete worms, Seymour Marine Discovery Center
11 May 2015
© Allison J. Gong

But there are gastropods that secrete calcareous tubes, too. They are the vermetid snails, the local species of which is Thylacodes squamigerus. This is one of my favorite animals in the low intertidal, probably because it is so delightfully un-snail-like.

There are three individuals of T. squamigerus in this photo:

The vermetid snail Serpulorbis squamigerus at Point Piños, 9 May 2015. © Allison J. Gong
The vermetid snail Thylacodes squamigerus at Point Pinos
9 May 2015
© Allison J. Gong
Serpulorbis squamigerus at Point Piños, 9 May 2015. © Allison J. Gong
Thylacodes squamigerus at Point Pinos
9 May 2015
© Allison J. Gong

Thylacodes is also a suspension feeder, but it gathers food in a very different way. When submerged, it spins out some sticky mucus threads that catch suspended particles, then reels in the threads and eats them.

So how would you tell these animals apart if you see them? Here’s a hint:  Look at the tubes themselves.

I invite you to use the comments section to tell me how you’d distinguish between Serpula and Thylacodes.

A naturalist goes in the field

Posted on by Allison J. Gong

This morning I took a small group of Seymour Center volunteers on a tidepooling trip to Point Piños (see red arrow in the photo below). Point Piños is a very interesting site. It marks the boundary between Monterey Bay to the right (east) of the point and the mighty Pacific Ocean to the left (west).

Map of Monterey Bay. Red arrow indicates Point Pinos.
Map of Monterey Bay. Red arrow indicates Point Piños.
Point Pinos, 9 May 2015. © Allison J. Gong
Point Piños in Monterey County
9 May 2015
© Allison J. Gong

As is my usual habit, we began our exploration on the Pacific side of the point. Almost immediately, Victoria found an octopus! And a couple of meters away, she found another one!

Octopus rubescens at Point Pinos, 9 May 2015. © Allison J. Gong
Octopus rubescens at Point Piños
9 May 2015
© Allison J. Gong

As we approach the summer solstice, the algae and seagrasses are at their most lush. Point Piños is a fantastic site for algal diversity; every time I come here I want to take some back with me so I can study it at the lab. Alas, collecting at Point Piños is not allowed even for someone (like me) who holds a valid scientific collecting permit.

Beds of Phyllospadix scouleri at Point Pinos, 9 May 2015. © Allison J. Gong
Beds of Phyllospadix scouleri (surf grass) at Point Piños
9 May 2015
© Allison J. Gong
Macroalgae at Point Pinos, 9 May 2015. © Allison J. Gong
Macroalgae at Point Piños
9 May 2015
© Allison J. Gong

And yes, that log-like object towards the upper-left corner is a harbor seal (Phoca vitulina). A handful of seals were hauled out on the rocks.

However, I was much more interested in the invertebrates. I wasn’t looking for anything specific, but in the back of my mind I was keeping track of certain nudibranchs and looking for small stars.

We did see many Patiria miniata (bat stars) in the 1-2 cm size range. Most of them were a bright orange-red color, but some were beige, yellow, or blotchy. There was one large (bigger than my outstretched hand) Pisaster ochraceus that was intensely orange. And Point Piños is always a good spot to see many of the six-armed stars in the genus Leptasterias.

Patiria miniata (bat star), about 1.5 cm in diameter, 9 May 2015. © Allison J. Gong
Patiria miniata (bat star), about 1.5 cm in diameter, at Point Piños
9 May 2015
© Allison J. Gong
Large healthy Pisaster ochraceus (ochre star), 9 May 2015. © Allison J. Gong
Large healthy Pisaster ochraceus (ochre star) at Point Piños
9 May 2015
© Allison J. Gong
Leptasterias sp., one of the six-armed stars, 9 May 2015. © Allison J. Gong
Leptasterias sp., one of the six-armed stars, at Point Piños
9 May 2015
© Allison J. Gong

In terms of nudibranchs there were many Doriopsilla albopunctata, a yellow dorid with tiny white spots. We saw quite a few of them crawling around on the emersed surf grass, as well as in pools. And of course Okenia rosacea (Hopkins’ rose) was there, although not in the huge numbers I was expecting.

Doriopsilla albopunctata at Point Piños, 9 May 2015. © Allison J. Gong
Doriopsilla albopunctata at Point Piños
9 May 2015
© Allison J. Gong
Okenia rosasea (Hopkins' rose nudibranch) at Point Piños, 9 May 2015. © Allison J. Gong
Okenia rosasea (Hopkins’ rose nudibranch) at Point Piños
9 May 2015
© Allison J. Gong

In the low zone I saw a few thalli of the intertidal form of Macrocystis pyrifera, the giant kelp that forms the forests that the California coast is famous for. I’d seen this intertidal form named Macrocystis integrifolia, but it appears that now the two forms (intertidal and subtidal) are both considered to be M. pyrifera. To my eye, the intertidal form differs morphologically by having rounder pneumatocysts (floats) and a holdfast that is less dense than the subtidal form.

Macrocystis pyrifera (giant kelp) growing intertidally at Point Piños, 9 May 2015. © Allison J. Gong
Macrocystis pyrifera (giant kelp) growing intertidally at Point Piños
9 May 2015
© Allison J. Gong

Hermit crabs are diverse and abundant at Point Piños. Here’s an example of Pagurus samuelis, the blue-banded hermit crab; even when you can’t see the blue bands on the legs, the bright red antennae are a major clue to this crab’s identity.

Pagurus samuelis (blue-banded hermit crab) at Point Piños, 9 May 2015. © Allison J. Gong
Pagurus samuelis (blue-banded hermit crab) at Point Piños
9 May 2015
© Allison J. Gong

When we climbed over the point to the Monterey Bay side, I found two of these little gastropod molluscs, which I didn’t recognize. They are about 1 cm long, with a brown lumpy mantle that can covers the shell, which is pinkish in color. After putting it out on Facebook that I needed help with the ID, a bunch of friends and friends of friends chimed in (thanks John, Rebecca, Barry, and David!) and I was able to determine that these little guys are Hespererato vitellina:

Hespererato vitellina (appleseed Erato snail) crawling on Phyllospadix scouleri (surf grass) at Point Piños, 9 May 2015. © Allison J. Gong
Hespererato vitellina (appleseed Erato snail) crawling on Phyllospadix scouleri (surf grass) at Point Piños
9 May 2015
© Allison J. Gong

On our way back up the beach we noticed long windrows of Velella velella, the by-the-wind sailors, washed up. While most of them were faded and desiccated, there were enough freshly dead ones that were still blue, which may have washed up on the previous high tide.

Windrows of Velella velella (by-the-wind sailor) washed up on the beach at Point Piños, 9 May 2015. © Allison J. Gong
Windrows of Velella velella (by-the-wind sailor) washed up on the beach at Point Piños
9 May 2015
© Allison J. Gong

All in all, a very satisfactory morning. I saw things I expected to see, some things I didn’t quite expect but wasn’t surprised to see, and some things I’d never seen before. That Hespererato vitellina was completely new to me, which is always exciting.

Next up:  What kinds of things live in white calcareous tubes?

Timing is everything

Posted on by Allison J. Gong

This morning I went here (see arrow):

Natural Bridges State Beach, viewed from Long Marine Lab, 4 May 2015. © Allison J. Gong
Natural Bridges State Beach, viewed from Long Marine Lab
4 May 2015
© Allison J. Gong

See how it’s covered in water? I took this picture at about 13:00, probably right at high tide. And of course when I was out there this morning at 06:00, it was low tide. It wasn’t the greatest of low tides but it allowed me to see what I needed to see and have a front-row seat watching the early morning surfers going up and down on the big swell that’s blowing in.

Obviously, visits to the intertidal need to be timed with the tide cycle. At this time of the year we get our lowest spring tides in the morning every two weeks or so, which is great for me because I am a creature of the morning. I can get up hours before the sun rises, but don’t ask me to do anything that requires any intense brain activity after about 21:30.

Low tide this morning was at 05:29, when it was still almost full dark. There was plenty of light to see by the time I got out to the rocks. The tide wasn’t very low and the swell was big, a combination that makes for some pretty spectacular wave watching. Here’s a view towards the marine lab from my intertidal bench; look at all that frothy water!

View of Terrace Point from Natural Bridges State Beach, 4 May 2015. © Allison J. Gong
View of Terrace Point from Natural Bridges State Beach
4 May 2015
© Allison J. Gong

So the water was big and the tide was mediocre, but it was still a glorious morning. Where I was the bench looked like this:

Looking seaward, Natural Bridges State Beach, 4 May 2015. © Allison J. Gong
Looking seaward, Natural Bridges State Beach
4 May 2015
© Allison J. Gong

What a difference seven hours can make! See that tiny black dot in the ocean? That’s a surfer. While I was out there none of the three surfers I was watching did any actual surfing.

I can’t seem to stop taking pictures of anemones:

A baby Anthopleura sola, measuring about 1.5 cm in diameter, 4 May 2015. © Allison J. Gong
A small Anthopleura sola, measuring about 1.5 cm in diameter
4 May 2015
© Allison J. Gong
Anthopleura xanthogrammica, 4 May 2015. © Allison J. Gong
Anthopleura xanthogrammica
4 May 2015
© Allison J. Gong
Anthopleura sola adult, 4 May 2015. © Allison J. Gong
Anthopleura sola adult
4 May 2015
© Allison J. Gong

My prize of the day appeared as I was walking back. I happened to look down at the right time and saw this little guy:

Little octopus in tide pool at Natural Bridges State Beach, 4 May 2015. © Allison J. Gong
Little octopus in tide pool at Natural Bridges State Beach
4 May 2015
© Allison J. Gong

I was able to watch the octopus for a couple of minutes. Its mantle was about 3 cm tall, and I’d guess that all spread out the animal was perhaps a bit larger than the palm of my hand. When I got up to move around to the other side of the pool for a different camera angle, the octopus oozed underneath the mussels and just disappeared.

Before it vanished I was able to catch it in the act of breathing.

Although it looks like a head, given the position of the animal’s eyes, the part of the animal that’s pulsating is the mantle. The visceral mass and gills are contained in the space enclosed by the mantle; not surprisingly, this space is called the mantle cavity. The octopus flushes water in and out of the mantle cavity to irrigate its gills. When it wants to swim it closes off the opening to the mantle and forces water out through a funnel which can be rotated 360° so it can jet off in any direction. But this time the octopus didn’t use jet propulsion. It just oozed away.

Graduation Day

Posted on by Allison J. Gong

Today was a big day for me. I got to graduate some of my baby urchins from glass slides onto coralline rocks. They were growing very quickly on the slides, chowing down on scum faster than I can grow it, so now it’s time for the biggest ones to really put their Aristotle’s lanterns to the test and chew up some rocks.

Coralline algae are red algae that have calcified cell walls, giving them a crunchy texture. They come in two morphs–erect branching forms and as encrusting sheets–and are pink in color. The corallines that I’m using for urchin food are growing as sheets on rocks. In the field it is not uncommon to see little urchins on coralline rocks, and their teeth are more than capable of grinding up the calcified algae.

So today I used my trusty frayed paintbrush to scoop up a total of ~90 urchins from their slides and dropped them onto rocks. I should have taken a picture of this valuable tool of mine, so you can see just how low-tech (and cheap!) my type of marine biology is.

Juvenile sea urchins (Strongylocentrotus purpuratus), age 97 days, 27 April 2015. © Allison J. Gong
Juvenile sea urchins (Strongylocentrotus purpuratus), age 97 days
27 April 2015
© Allison J. Gong

The largest urchin on this rock has a test diameter of ~2800 µm. Almost 3 mm now!

Here’s a closer view of three of the urchins in the photo above:

Close-up of three urchins (S. purpuratus) on coralline rock, 27 April 2015. © Allison J. Gong
Close-up of three urchins (S. purpuratus) on coralline rock
27 April 2015
© Allison J. Gong

It didn’t take long for the little urchins to start crawling around on their new substrate. I think they’ll be happy with this more natural surface to explore and food to eat.

In the meantime, the remaining babies will stay in their jars or on their slides, eating scum. I will continue graduating urchins to rocks as they get too big for slides, feeling more nostalgic each time.

Just think, only 97 days ago these urchins were zygotes! It’s not often that you can say that you’ve known an organism for its entire life, from the moment of fertilization. I am grateful for the privilege of having the opportunity to undertake such an intimate study of these animals’ lives. Although I try at least once every year, this is my first successful urchin spawning since 2012. Those animals, by the way, are what I call my most perfect urchins because, well, they just are. I had originally thought I could use them for dissection, but after caring for them as larvae and the three years since they’ve metamorphosed, I just can’t bring myself to sacrifice them. They are simply perfect.

I don’t think I could ever get tired of this.