Sea urchins have no manners

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.

Posted in Marine biology, Marine invertebrates | Leave a comment

And we have fledged!

Yesterday afternoon when I got home I checked out the red-tailed hawk nest across the canyon and didn’t see anybody home. Then I started scanning the trees on both sides of the canyon to see if the parents were around. While I was looking the dad flew in with prey and perched on the top of one of the trees. But he didn’t start eating right away so I thought he might have been showing the prey to the kids. Sure enough, we found one of the juveniles perched just a short distance away.

Buteo jamaicensis (red-tailed hawk) father (left) and newly fledged offspring (right), 14 May 2015. © Allison J. Gong

Buteo jamaicensis (red-tailed hawk) adult male (left) and newly fledged offspring (right), 14 May 2015.
© Allison J. Gong

 

The adult male’s plumage is nice and sleek, and he perches quite easily on a branch that sways dramatically in the afternoon wind. The juvenile’s feathers are rumpled and its head looks small, probably because it hasn’t been feathered very long, and it had some problems with balance.

At some point the juvenile managed to hop over to its dad, who then shared some of his food.

Buteo jamaicensis (red-tailed hawk) adult male and juvenile, 14 May 2015. © Allison J. Gong

Buteo jamaicensis (red-tailed hawk) juvenile (left) and adult male (right), 14 May 2015.
© Allison J. Gong

So we knew for a fact that at least one of the juveniles had fledged; however, we didn’t find the other juvenile anywhere. We did see the adult female perched atop a tall snag on our side of the canyon; she was looking around but didn’t seem worried so we figured that the second juvenile at least wasn’t on the ground or in some other danger.

And lo and behold, as the sun was beginning to set and light the other side of the canyon, we found both juveniles and the adult female perched on trees across the way. So both of the kids had fledged successfully!

Buteo jamaicensis (red-tailed hawks), newly fledged juveniles (left and lower right) and adult female (upper right), 14 May 2015. © Allison J. Gong

Buteo jamaicensis (red-tailed hawks), newly fledged juveniles (left and lower right) and adult female (upper right), 14 May 2015. © Allison J. Gong

I don’t know what the juvenile on the left is doing and why it appears not to have a head. We still haven’t actually seen either of the juveniles flying, but by the time it was getting dark both had returned to the nest for the night. I imagine they slept well after all the day’s exertions!

 

Posted in Birds, General natural history | Leave a comment

I’m famous!

Well, fame is all relative, right?

VICE magazine’s May 2015 issue is focused on environmental crises of various kinds. One of the feature articles is on sea star wasting, which I’ve blogged about before, beginning in September 2013. The author of the VICE article, Nathaniel Rich, came out to the marine lab and interviewed me and some other folks back in February, and a photo crew came out to do a shoot in March.

Here’s the article. Overall I think Nathaniel did a good job; this is one of the better lay person articles I’ve read about wasting. He was able to convey the concern we biologists have about wasting, and the effects it could have on the ecology of the intertidal and subtidal marine habitats, without being too alarmist.

There is one glaring mistake in the first part of the article, which I’m positive must be a misunderstanding of something that I may have said to him. Can you find it?

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Almost branchers

Our red-tailed hawk chicks are sooo close to fledging now! I’ve been told that the tree-nesting raptors usually first leave the nest to hop around on branches; hence they’re called “branchers.” This afternoon I watched the chicks and was able to catch some of the maneuvering, which included hopping around the edge of the nest.

One of the chicks seems more adventurous than the other. I know that female raptors are larger than males, so I think that males reach their fledging size sooner than their sisters. Which would mean that this earnest almost-brancher is a boy. He’ll be flying soon!

Posted in Birds, General natural history | 4 Comments

When is a tube worm not a tube worm?

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 Piños, 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 Serpulorbis squamigerus. See how even the names of these animals conspire to increase confusion among naturalists? Be that as it may, Serpulorbis is one of my favorite animals in the low intertidal.

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

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

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

Serpulorbis squamigerus at Point Piños, 9 May 2015. © Allison J. Gong

Serpulorbis squamigerus at Point Piños, 9 May 2015.
© Allison J. Gong

Serpulorbis 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 Serpulorbis.

Posted in Marine biology, Marine invertebrates | 4 Comments

A naturalist goes in the field

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, 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?

Posted in General natural history, Marine biology, Marine invertebrates | Leave a comment

Practice makes perfect

The red-tailed hawk chicks across the canyon from us continue to practice their flapping, preparing to take their eventual first flights. We frequently see one of the chicks standing up in the nest, flapping away and whacking its sibling in the head. They’re too big now for both to be flapping at the same time.

The parents are being kept busy bringing food to their hungry offspring. One or the other is often perched on the top of a pine tree within sight of the nest occupants, usually being pestered mercilessly by a marauding crow, while the other is out hunting. The grown-ups are also, I think, trying to entice the kids out of the nest, by hanging out where the they can be seen and showing the kids how it’s done. I expect that the young ones will fledge in the next couple of weeks. We may not see the actual fledging flights, but I’m certain we’ll hear about them.

Posted in Birds | 2 Comments