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It has been almost a month since my big female whelk started laying her eggs, and the embryos seem to be developing nicely. The first time I witnessed this phenomenon I saw the egg capsules begin to turn black, and worried that the eggs inside were dead and decomposing. But the cool thing about Kelletia development is that the larvae themselves become darkly pigmented as they develop, which we see as an overall dingy grayness of the egg capsules:

Kellettia eggs

 

Nosy as ever, I pulled one of the egg capsules off the side of the bin and took it back to my desk for closer examination under my dissecting scope. At the "top" of the capsule (the end that is attached to the bin), the material was quite thin, and I could some vague dark lumps inside. They were slowly moving around, so I knew they were alive.

Individual larvae resemble bubbles with dark stuff inside.
Individual larvae resemble bubbles with dark stuff inside.

 

Viability! This makes me happy and encourages me to "liberate" a few larvae to look at under higher magnification. I squeezed out a few veligers and put them under a coverslip with just enough water to keep their shells from cracking but not enough to let them swim away. Here's a tip for observing small aquatic critters under a microscope:  If you make their universe (i.e., the drop of water you are observing) small, they will be less able to swim away from you. Flattening the drop of water with a judiciously placed coverslip will also help immobilize the creature, as well as taking best advantage of the microscope's optics.

Early veliger of Kelletia kellettiiNot too much to look at while stationary, is it? You can see a coiled shell (this is a snail after all) and some blobby structures inside it. At this stage the larva isn't feeding and relies on yolk reserves provided by the mother when she deposited the eggs. Some of the opaque stuff inside the shell is yolk and other bits are various parts of the digestive system. At about 11:00 just underneath the shell there is an elongated transparent area: the larva's heart; you can see it beating in the video below. The light mohawk-looking structure facing to the right is the larva's velum, a lobed ciliated structure that the animal will use to swim after it hatches. The last structure of note is the wedge-shaped thing that points to about 5:00; this is the larva's foot, on the back of which sits the operculum that is used to close up the shell.

After a bit of trial and error I was able to catch some decent video footage through the microscope of a trapped larva:

Kellettia larva under compound scope

The larva rhythmically extends and retracts its velum. Because of the coverslip the larva can't go anywhere, but if unencumbered it would be able to use that velum to zip around really fast. It is very difficult to keep up with swimming veligers under a microscope!

My guess is that the larvae will begin hatching on their own in the next couple of weeks. They will be washed out of their tub and down the drain of the seawater table, to take their chances in the big ol' Pacific Ocean.

3

This week my female Kellet's whelk (Kelletia kelletii) started laying eggs. She's been doing this every summer for the past several years. She lives with one other whelk, presumably the father of her brood, as the eggs are both fertilized and viable even though I've never seen the snails copulating.

That's right, copulating. Whelks are predatory marine snails, some of which get quite large. My big female's shell is a heavily calcified 12 cm or so; she's a beefy mother! Her mate is smaller, but other than the size difference I wouldn't be able to tell them apart. Anyway, whelks copulate, with the male using a penis to transfer sperm into the female's body. Not very different from the way we humans do things, actually.

So at some point in the recent past my whelks copulated, and this week the female began depositing egg cases on the walls of their shared tub. I first noticed them on Monday, but she may have started over the weekend.

Female whelk (right) laying eggs. ©Allison J. Gong
Female whelk (right) laying eggs.
© 2013 Allison J. Gong

Those pumpkin seed-shaped objects are the egg capsules. Each is actually about the size and shape of a pumpkin seed and has a tough outer covering that contains 20-50 developing embryos. After the entire clutch is lain, which usually takes this particular female a week or so, the mom will leave the eggs to develop on their own.

I'll keep an eye on these eggs for the next week or so, and might be able to get some photos of the embryos and larvae as they begin developing. Keep your fingers crossed!

We are fortunate to have a lot of wildlife in our backyard, which is actually a canyon. On any given day we can look out and see finches and hummingbirds squabbling over their respective feeders, jays trying to steal whatever they can, and hawks either swooping through the brush or soaring overhead. The soundtrack of afternoons around here is punctuated by the sharp high-pitched "teek" of towhees and the chickadees can be heard just about any time of day. And every once in a while a mockingbird tricks me into thinking that I'm hearing something that I'm not.

Among our favorite birds is our state bird, Callipepla californica, or the California quail.

California quail male (left) and female (right)
California quail male (left) and female (right). Source: Wikimedia Commons

In our canyon we have quail year-round, and we call them collectively the "dudes." The males, with their typically gaudy male plumage, are the dudes and the females are dudettes. In the winter, the quail form a covey of anywhere from 15-25 adults of both sexes, banding together for safety.

Males (dudes) in a winter covey
Males (dudes) in a winter covey

Once the days begin to lengthen in the spring, however, the males begin squabbling for territory and females, and the covey breaks up. After that we see the quail in male-female pairs. Interestingly, the pairs will forage in more or less the same area, but when one of the males crosses some invisible (to me) line the other will get all bent out of shape. Females seem to forage wherever they want.

Nesting occurs in the bushes somewhere, and in July we see the babies for the first time. Usually it's the dads who bring out the dudelets; I think the females may be incubating a second clutch of eggs at this time.

Needless to say, the dudelets are very cute. The youngest we've ever seen were little speckled fluffballs. It's hard to see in this photo, but at this age the dudelets already have tiny plumes.

Dudes and dudelets
Dudes and dudelets

Like most baby birds, the dudelets grow fast. After a couple of weeks they've grown more feathers and begin to look more like their parents. This year (2013) we missed the fluffball stage and today we saw the dudelets for the first time. They were brought up by both parents; we saw two males, one female, and 4-5 dudelets. It's hard to get an exact count because these birds are so good at melting into the shrubs and becoming invisible. Even though there was a dudette present, it was the dudes that were watching over the dudelets.

Watchful dude and two dudelets
Watchful dude and two dudelets

Eventually the dudelets will grow up and the males will have to disperse to find and defend their own territories. The winter covey will re-form, and next spring we will be on the lookout again for the next generation.

2

Over the Memorial Day weekend I took my students out on the early morning low tides at Natural Bridges State Beach.  While they were ooh-ing and ahh-ing and filling out their assignment worksheet, I was playing around with my new camera, taking pictures in the water.  Because I am not a photographer and sea anemones just sit there, they quickly became my favorite subjects.  Not to mention the fact that they are simply  beautiful and photogenic creatures.

At Natural Bridges we have four species of anemones in the genus Anthopleura:

  • A. xanthogrammica - giant green anemone
  • A. sola - sunburst anemone
  • A. elegantissima - aggregating anemone
  • A. artemisia - moonglow anemone

Of these species, the first two are notable for their large size.  At Natural Bridges they can get to be the size of a dinner plate.  They live side-by-side in tidepools, and since there are many deep-ish pools at Natural Bridges they are among the most conspicuous animals in the intertidal along the northern California coast.

Anthopleura sola (left) and A. xanthogrammica (right) in a shallow pool at Franklin Point.
Anthopleura sola (left) and A. xanthogrammica (right) in a shallow pool at Franklin Point.

It's easy to identify these animals when they're sitting right next to each other.  The difficulty comes when you see only one in a pool by itself with nothing to compare it to.  In a nutshell, here are some things you can use as clues to determine which species you have in front of you.

Let's start with Anthopleura xanthogrammica, the giant green anemone.  This animal's oral surface and tentacles are a solid color, varying from bright green to golden brown.  There are no conspicuous stripes on the central disc and the tentacles are relatively short and stubby, without any white patches.

Anthopleura xanthogrammica, photographed at Natural Bridges State Beach
Anthopleura xanthogrammica, photographed at Natural Bridges State Beach

Anthopleura sola, on the other hand, usually has distinctive radiating lines on the oral disc.  Hence the common name of Sunburst Anemone.  Its tentacles are generally longer and more slender than those of A. xanthogrammica, and often have sharp-edged white patches.  Sometimes the tips of the tentacles are tinged a pale purple.  Anthopleura sola are usually brownish-green in color, and I haven't seen any that are as bright green as the A. xanthogrammica anemones.

Anthopleura sola, photographed at Natural Bridges State Beach
Anthopleura sola, photographed at Natural Bridges State Beach

That's all well and good, but sometimes you come across an individual that doesn't completely follow the rules.  Or rather, it looks like it could belong to both species. Such as this fellow (fella?):

Hmmm...sola or xanthogrammica?
Hmmm. . . sola or xanthogrammica?

The animals obviously don't read the descriptions.  This one has xanthogrammica shape and overall color, but those lines on the disc read as sola-ish.  I would call this one a xanthogrammica.  What do you think?

The birds do it, the bees do it, and now the frogs are doing it.  There's a small clump of trees between two of the houses across the street, and I think that's where a male Pacific chorus frog has staked his claim.  Every evening for the past few weeks I've heard him singing away.  Often you'll hear several frogs singing at the same time, but this particular guy's call is much louder and more piercing than the others.  What I particularly like about this sound recording is that it begins with a solo, and other frogs join in to make a joyful noise.

The Pacific chorus frog (Pseudacris regilla), sometimes erroneously referred to as the Pacific tree frog, is the only frog that ribbits.  It couldn't possibly be mistaken for anything else.  In fact, its song is so iconic of "frogness" that it is universally used in movies and other Hollywood products taking place anywhere in the world, despite the fact that this little singer lives only along the western coast of the US.

Most Pacific chorus frogs don't live in trees
Most Pacific chorus frogs don't live in trees

Why is it wrong to call these guys tree frogs?  Because they don't live in trees, silly!  At least, not exclusively in trees.  Along the central California coast they live in grassy areas from the coast up into the hills.  I start hearing them in winter, as the rains form puddles and small ponds, but they stop singing when they hear people approaching.  To me, they are part of the soundtrack of spring in California.  While most of the singing happens at night, I often hear them singing during the day at the marine lab.  Many times the males are singing together -- hence the name chorus frogs.

Considering their ability to make a lot of noise, Pacific chorus frogs are little guys.  Big ones are only 5 cm long.  They vary in color from brown to green, and the color of an individual can change throughout the year.  They have a very distinctive dark horizontal stripe that runs through the eye, making them look like, well, chorus frogs.

Pacific chorus frog (Pseudacris regilla) on the stem of a sunflower
Pacific chorus frog (Pseudacris regilla) on the stem of a sunflower

Like all frogs, chorus frogs are tied to water for reproduction.  Once the rains have started, male frogs migrate to wet areas and set up shop.  Their "krick-et" calls attract females, and the frogs pair up and do what comes naturally to most animals in the springtime.  The female lays eggs in calm, still water and the male fertilizes them as they are deposited.  Tadpoles develop in the water and, hopefully, metamorphose into froglets in due time.

Eventually the mating season will end, and the frogs will stop singing until next year's rains.  I will miss them when they go away, but for the next little while the soundtrack of spring will play every evening.

 

1

We are still about a few days away from the vernal equinox, but it is impossible to mistake the signs of spring:  Trees are blooming (gesundheit!), bees are buzzing, and birds are singing. In our canyon, the California quail have disbanded their large winter covey and are foraging in male-female pairs. In the past few weeks I've watched and listened to red-shouldered hawks claiming their territory. All that I'm waiting for is the return of the downy woodpeckers drumming on the utility poles and the arrival of mud-carrying swallows at the marine lab to know that spring has truly sprung.

One of my favorite spring sights--and sounds!--is the red-winged blackbird (Agelaius phoeniceus). They are in California year-round, but their raucous mating displays make them much more visible in springtime.

Male red-winged blackbird in display posture
Male red-winged blackbird in display posture

Male red-wingeds are a glossy black with puffy red epaulettes, which they flash as they are calling. This time of year it is common to see a bird perched on the end of a twig, showing off his shoulders and his loud, clear voice.

Here's what it sounds like: Call of red-winged blackbird

The conspicuous markings and piercing call serve to advertise a male's territorial claim. He states very emphatically, "This is my patch of rushes, so BACK OFF, DUDES!"  If he is successful in holding off interlopers, a male may mate with several females within his territory. This is a Good Thing, no? Females benefit from this arrangement because a male who can stake out and defend a territory is presumably vigorous and will pass those healthy alleles to his offspring. So it's a win-win situation and the best possible baby blackbirds are produced every generation.

Sexual selection in action!  Gotta love it!

Sometimes even a naturalist gets to go on vacation, and I was fortunate enough to get to spend a week in Kaua'i.  My favorite spot on the island was the Kilauea Point National Wildlife Refuge on the north shore of the island, where I got to see albatrosses, frigatebirds, and boobies in flight, as well as humpback whales breaching and flipper-slapping offshore.  Amazing!

As much fun as it was to watch all these birds flying around, it was just as entertaining to drive through the adjacent neighborhood and watch albatrosses in people's front yards.  I'd love to have albatrosses in my front yard, but alas, it's not going to happen in California.

Just what are those albatrosses doing in people's front yards, you ask.  Good question.

The Laysan albatross, Phoebastria immutabilis, is a north Pacific species which breeds primarily in the northwestern Hawaiian Islands.  Like all seabirds, their food comes from the ocean.  Albatrosses are known for their super-efficient gliding flight; their long, narrow wings are the inspiration for the design of gliding planes.  The Laysan albatross has a wingspan of 6-7 feet.  On the ground they look somewhat like ordinary gulls, but in flight and close-up they are truly magnificent birds.

Albatrosses are also extremely long-lived birds.  The bird in the photograph below has a band on her right leg.  The information on the band tells biologists when the bird was banded.  This female bird was 60 years old when she was photographed at Midway Atoll in 2011 by John Klavitter of the U.S. Fish and Wildlife Service.

Laysan_albatross_fws_age60in2011

It turns out that albatrosses return to the sites where they hatched as they get old enough to breed.  The Kaua'i albatrosses had been using the north shore of the island as a breeding ground when the housing developments were built, and apparently don't mind either the construction or the people living there.  The human residents take great pride in their avian neighbors, putting up signs telling tourists to keep their distance and leave the birds undisturbed.

We made several passes through the neighborhood to look at the albatrosses, and finally got some good pictures.

Albatross in someone's front yard in Princeville, Kaua'i
Albatross in someone's front yard in Princeville, Kaua'i
A trio of Laysan albatrosses on a beautifully manicured lawn.
A trio of Laysan albatrosses on a beautifully manicured lawn.
Laysan albatross right next to the driveway!
Laysan albatross right next to the driveway!

Some of the albatrosses on lawns are incubating eggs, and some are juveniles hanging out and scoping out future mating possibilities.  If all goes well, albatrosses will be nesting in and fledging from this neighborhood for many decades to come.

1

I was making my usual feeding and checking rounds at the marine lab last Wednesday, when I saw this:

Pugettia producta, molting.  Time 10:09:12

This crab is a kelp crab, Pugettia producta. It is one of the common crab species on the California coast; you can find them in the low intertidal clinging to algae. Many of them are this golden-brown color, coincidentally(?) the same color of the kelp Macrocystis pyrifera. Juveniles are often reddish or dark brown in color, again matching or blending in with the algae where you see them. This particular crab has always been this color, at least since it has been in my care.

Crustaceans, as all arthropods, periodically molt their entire exoskeleton in one fell swoop. The exoskeleton splits along the transverse seam between the carapace and the abdomen, then the crab sort of slithers out backward. The entire exterior of the body, including legs, antennae, and mouthparts, is left behind as a larger version of the crab scuttles away to hide out for a few days until its new shell hardens.

I've kept lots of crabs and seen lots of molts show up in their tanks, but have never caught one in the act before. From when I started watching, in the photo above, to the final wiggle out of the old exoskeleton took no longer than 5 minutes.  Here's the sequence of photos documenting the molt:

Pugettia producta molting. Time 10:09:41
Pugettia producta molting. Time 10:12:18
Pugettia producta, molting. Time 10:13:57

Pretty nifty, eh?

 

Just in time for Hallowe'en!  I have photographic evidence that some of our bees have been taken over by parasitic phorid flies. These flies are a group of diverse animals, including wasps and nematode worms, described as "parasitoids." These are not your average parasites, which generally do not cause lethal damage to their host, although as in most areas of biology it is difficult to draw a solid distinction between the two.

It is generally in a parasite's best interest to keep its host alive, at least long enough for the parasite to complete its development and disperse to a new host--if the host dies, the parasite dies with it. Parasitoids, on the other hand, flat out kill the host. A famous example are the parasitoid wasps that lay their eggs inside the bodies of caterpillars; the wasp's larvae hatch inside the caterpillar and slowly devour it from the inside out. I'd link to a photo of this horrendous phenomenon, but those of you who know me personally know that I can't look at pictures of caterpillars. Makes my hands sweat just thinking about looking at one. Eww.

Apocephalus borealis is a phorid fly native to North America. It parasitizes various hymenopteran insects, including paper wasps and bumblebees. In January of this year a paper came out confirming that honey bees, Apis mellifera, are also parasitized by the fly. The authors speculate that the fly may be part of the melange of misfortunes resulting in Colony Collapse Disorder (CCD).

The really interesting thing, to me as a beekeeper, is that the samples analyzed were from the San Francisco Bay area. Not only that, but the authors are soliciting additional data from beekeepers and citizen scientists and have put together a cool Zombee Watch program. Hmm. I'm a scientist and a beekeeper in the greater SF Bay Area, so I thought I'd keep an eye out for any bees that were acting strangely as described in the paper. Come to think of it, last fall (November-ish, I think) we went through a period of about a week when bees would get into the house in the evening. It was clear that they were coming towards the light, but I couldn't figure out what they were doing flying around in the dark when they should have been back in their hive. At the time I didn't know to look for phorids, though.

One evening this past July, a few days before leaving on vacation, I noticed a bee on the screen door. She was obviously dying--hardly breathing, non-responsive to my breath or touch--and I thought it might be worthwhile seeing if she were parasitized. I didn't have time to do anything official according to the Zombee Watch protocol, so I just put her in a ziploc bag and forgot about her. A few weeks later I came across the bag again and--lo and behold!--the bee was dead and there were four pupae and four dead flies in the bag with her.

I finally got around to taking pictures of the bee corpse and her equally dead killers:

Dead honeybee with four pupae (bottom left) and four dead phorid flies (bottom right).

Flies and other holometabolous insects go through four distinct life history stages: egg, larva, pupa, and adult. The larva is a feeding stage (think caterpillar); in the case of flies the larva is the critter we call a maggot. After feeding for a certain amount of time the unwinged larva encloses itself into a cocoon and pupates. Inside the pupa the larva undergoes a drastic metamorphosis. The adult stage that emerges from the pupa looks entirely different from the larva:  it has legs and (usually) wings.

Empty pupae of the phorid flies

The adult phorid flies actually look kind of cool. If they weren't troubling my honeybees, I'd like them.

Adult phorid flies

The female phorid fly lays eggs inside the body of a live host. Maggots hatch out of the eggs and cause behavioral changes in the host. Parasitized honeybees abandon the hive and fly around at night, which is why they are easy to catch. They also get disoriented and walk around like, well, zombees. Eventually the fly larvae (maggots) burst out of the bee's body and pupate outside the bee. The host inevitably dies.

Now, isn't that a lot creepier than your average Hallowe'en tale?

I've shown you how sea urchin eggs are fertilized in the lab, and you've watched the fertilization membrane develop in real-time.

One day a few years ago, my colleague, Betsy, and I set up shop to spawn urchins.  We do this just about every year because it is super fun and we both enjoy watching larval development; plus, if all goes well we end up with a cohort of urchins whose genetic lineage is known to do growth experiments.

Anyway, after we shot up the urchins and they began spawning we took a sample of eggs to check on their shape.  They should be uniformly round and about 80 microns in diameter.  The first slide that we set up looked like this:

How did this egg get fertilized?

See that egg in the center, with the fertilization membrane?  Somehow that egg got fertilized.  This sample of eggs had not been in contact with sperm or any tools that might have been in contact with sperm, so how did this single egg get fertilized?  None of the other eggs on the slide had been fertilized, nor was there any visible sperm swimming around.

Betsy and I never did figure out what was going on here.  We decided it was one of the Mysteries of Life, and continue to marvel at all the complexities of life that we don't understand.  That's what makes being a biologist so cool--it wouldn't be nearly as much fun if we already understood everything.

In my next post I'll show you pictures of sea urchin larval development.

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