Blog revival

 Hello, world! It’s been a very long while. So much has happened: I had a baby, as announced in the last post before this long hiatus… that was seven long years ago! I moved back to the Philippines in 2016 (family in tow), and now I’m an associate professor of biology at the University of the Philippines Visayas. Very busy and exciting times, I even forgot I had started a science / natural history blog. 

 Science blogging only came back to my mind because I asked my grad students to write blog posts as one of their requirements in the Biogeography class I’m handling this sem. I plan to have them guest-post in this blog soon, so watch out for more activity in this space.

Rabbits of the sea [Late post]

[this is a late post, composed in May 2013 and only published now!]

May is the time for baby rabbitfish.

Everywhere on the lagoon of Ipan, I found large schools of juvenile rabbitfish, nibbling away at the seagrass. It's the annual "run" of the babies, migrating from the open ocean towards the reef flat and lagoons, where the lucky few mature into adults (the rest are eaten by other fish -- and by humans too).

Both baby and adult rabbitfish are highly sought after for eating. In the Philippines, the baby rabbitfish or padas are easily harvested in the thousands using seines or bag nets. The padas are then turned into very good fish bagoong (=fermented fish paste). I read that baby rabbitfish need to be harvested before they reach the seagrass meadows, because once they start feeding on seagrass the taste turns bitter.

The adult rabbitfish are also good to eat. In the Philippines they're fried, grilled, in sinigang, and butterflied open and salted and dried. The adults are not called padas anymore - they're known as danggit, samaral, barangen, kitang, or a whole bunch of other names - depending on the language and on the species. They're caught using v-shaped fish corrals (baklad) that trap migrating adults into a narrow area where they can be scooped out with a net. Fishermen know that the adults have to migrate from the reef flat to deeper waters so they can reproduce, so they set up their baklad to catch all they can during that time of year.

While good to eat and high priced, it's not really sustainable to intensively harvest both the babies AND the reproductive spawners of the same species. Especially when you have so many baklad on the reef flat that hardly any of the spawners can survive to reproduce. In fact, huge declines have been reported in rabbitfish catched in various parts of the Philippines. And by huge declines, I mean catches that are less than half what they used to be... and still plummeting.

Here on Guam, the baby rabbitfish are called mañåhak, the adults are known as sesyon or hiteng. In between their baby and adult stages, they're known as dagge'.

On Guam two species are common: Siganus argenteus (hiteng), which is plain and silvery with a forked
tail, and Siganus spinus (sesyon), which has a scribbly pattern. You can see both species in this photo:

(I think the S. argenteus is bigger because it migrated from the ocean slightly sooner than S. spinus).

One cool thing about rabbitfish is that they can change color! When a school swims over bare sand or rock, it's grey-silver in color, and when it's amongst seagrass the color subtly shifts to green! It's difficult to photography, but can you kinda see the difference?

 

 

I know it doesn't look like much in photos, but in real life it's actually really pretty.  It may not be a very dramatic color change like you'd see in an octopus, but I'd like to see YOU to try to do better than the rabbitfish!

I don't know how much harvesting is going on here on Guam. Are rabbitfish overharvested here, too?

 

Hello, blog!

Why hello again, world! It's been a loooong since I last posted.. too long! And honestly, it's been hard to find the time to write - or the ability to hold a camera long enough to take a critter pic. Mostly I blame this cute little bug:

Oh yes oh yes, the adorable F1 generation! Thankfully bébé's steadily growing, and so I'm getting a bit more time for other pursuits. Blogging is back on the agenda, oh yeah!!!! But... taking photos is still hard. So expect some picture-less posts (sorry). I also plan to diversify things a bit, add some natural history stories from papers I've read & so on. Maybe even some terrestrial stuff! Going out on a limb here!

Before I leave you, let me just post a link to my latest-greatest inspiration for taking up this blog again. Y'see, I just published a major chapter out of my dissertation*, a phylogenetic study on the coral-dwelling barnacles. And then, something really cool happened: our paper got featured in Deep Sea News!!! You gotta admit, all those memes look pretty awesome....

So, the DSN post is my inspiration to continue sharing my passion for natural history with the rest of the world. Stick around, wontcha.

* Malay, MCD and F Michonneau. Phylogenetics and morphological evolution of coral dwelling barnacles (Balanomorpha: Pyrgomatidae). Biological Journal of the Linnean Society 113: 162-179. DOI: 10.1111/bij.12315

Camouflaged Ninja

Yesterday there was a pretty good afternoon low tide, so we poked around the nearby reef flat to see what there was to see.

Look what we found!

We typically see this kind of octopus at night, hunting in the very shallow intertidal. It was our first time to see it in the daytime. This octopus is a master of camouflage, able to change its color in a wink.

In the second picture above, its color exactly matches that of the Padina seaweed where we found it. When we let the little guy (or gal, not sure) go, it scooted right back into the Padina:

And the color match is truly remarkable. In the photo above you can see four of the arms, as well as the bulb-like mantle that contains most of the internal organs. To the right of the photo is a clump of Padina. If the octopus wasn't moving, we'd never have spotted it.

When I went in very very close with my camera, the octopus paled to a threatening white. But it's still only barely visible against the coralline sand. Really, only the angry white eye staring up at me gave it away:

Octopus are probably the brainiest invertebrates out there. They're the lightning-fast camouflaged ninjas of the reef flat.

Sneaky Menace

Just look at that beauty. This, my friends, is a scorpionfish. One of the sneakiest, most aggravating of all reef fish. Sorry, do I sound biased?!? It must be because 2 years ago my foot had an intimate encounter with a scorpionfish (or perhaps a stonefish, I'm not sure which because I never saw the bugger). The encounter can be summed up in one word: AGONY. You do NOT want to get in contact with any of its fin spines, as they are all tipped with poison (OK, based on the level of pain, it was more likely a stonefish. But I'm now biased against all scorpaenids).

But even I have to admit, this is a gorgeous fish.

  

 

But what gives, scorpionfish? Why be venomous AND extremely well camouflaged?!? I understand the use of venom, it keeps you safe -- but most venomous animals advertise the fact with gaudy coloration (like your cousins the lionfish). And I also understand the need for good camouflage for an ambush predator like yourself. But what's the point of having BOTH strategies? That's just.... waaayyyy too sneaky.

 

PS Please compare the butt-ugly face  of a scorpionfish with clam (not sure of the ID - maybe the jewelbox clam Chama?). The similarity is pretty cool.

Artists of the floating world

Well, well! A simple walk on the beach yielded the most amazing finds. Introducing... Janthina! Otherwise known as the purple storm snail, this unusual snail spends its life bobbing along the surface of the ocean. It floats using an ingenious raft of bubbles (made of hardened mucus) that it sticks to its shell and foot.

The white things on the snail shell are gooseneck barnacles (Lepas sp.), they like to stick to any old floating thing, such as bits of wood, plastic, styro, etc. Here is a better view of the barnacles, sticking out their cirri (feeding appendages).

Notice that the shell of Janthina is dark purple on top, and very pale lavender on the bottom (well, actually it's the bottom of the shell that's dark & the top that's light, but as you see in this snail top & bottom are reversed). The reason for the two-tone shell? The top is dark so that predators above the surface of the water cannot see the shell, and the light colored bottom means that Janthina is also well camouflaged from hungry predators coming from below it (the light color blends well with the sky above). This is a good example of countershading. Many fish employ the same trick (think about how many fish are blue on top with white bellies...).

I think Janthina looks just gorgeous against a black background...

Here's a closeup of the mouth and oral tentacles. Guess what Janthina feeds on... hint, it's a floating artist too!

Janthina feeds only on floating siphonophores, which are relatives of jellyfish. The most abundant siphonophore here on Guam is the man o'war or bluebottle, Physalia sp.! Notice its gas-filled transparent float/sail, which allows it to stay on the surface of the water.

Geeky taxonomic aside: there's some debate about whether Physalia is only 1 species or several. Right now only 1 species is formally recognized, Physalia physalis. But others argue that the Pacific form is a different species, and that it should be named Physalia utriculus. Overall the Pacific form seems to be smaller than the Atlantic form, and it only has 1 long "tentacle" (seen in the pic below), whereas the Atlantic critter has several long "tentacles". The jury is still out on this issue, but at least 1 recent study has shown more genetic diversity in Physalia than previously thought.

About those "tentacles": they aren't really tentacles. And actually Physalia isn't actually a single animal... it's a colony! Each tentacle, and also the gas-filled float, are actually separate individuals, known as zooids. Physalia has both polyp-zooids and medusalike zooids. Man o'wars start out life as just 1 polyp, that soon buds off other zooids that remain stuck together, forming a cooperating, floating colony. There are zooids specialized for catching prey (the long "fishing tentacle" in the pic above), and others specialized for defense, digestion, reproduction, etc. Of course, there's also one zooid specialized for floating. Can you guess the functions of the different zooids in the picture?

Oh, did I mention that Physalia stings are NASTY?... those beadlike structures you see on the finer zooids are batteries of stinging nematocysts. And if you're wondering what the dark granular structures are on the other zooids -- so am I. So drop me a line if you have an idea what they are. Thanks.

Since the members of the colony cannot survive if separated, Physalia is kinda in a grey area in between being a colony and being a single individual. I first learned about this strange creature/colony from Stephen Jay Gould's excellent essay "A Most Ingenious Paradox", published in the book "The Flamingo's Smile". 

 I picked up the Man O'War not only because it's pretty, but also because I was curious to see if my Janthina would eat it. So I put them together in a jar... here's a top view. You can see that the snail has its buccal mass (=mouth + pharynx) all extended, as if it was ready to chomp the siphonophore into little purple pieces.

Alas, it was not to be. I kept the critters alive for 2 days, but Janthina never did eat the Physalia. And sadly, the Man o'war died soon after. They're pretty much impossible to keep alive in captivity.

Couple more gratuitous underwater shots, just because these guys are so pretty. And hey, in the future I might even upload a video of the Physalia curling & uncurling its pretty zooids. Stay tuned!

 

Betcha can't see me!

: )

Annoying photo-bomber. Dang.

 There must be a lot of snorkellers feeding the fish at Ypao Beach, otherwise a fishie wouldn't come this close to me!

Here's a cutie: Hexabranchus sanguineus, commonly known as a Spanish Dancer nudibranch. This sea slug occasionally swims, and it does so by undulating its frilly mantle extensions -- looking for all the world like a flamenco dancer.

Is this a sea cucumber that's just happy to see me?

...why yes it is, dear Virginia! Did you know that sea cucumbers spawn (i.e. have sex) by raising their "head" ends and releasing egg or sperm from special little pores? Yeah, I knew that too! But what I DIDN'T know is that THIS particular species buries one end in the sand and starts spawning from a diagonal position! What an acrobat!! I took a closer look & I think it's a male, and yep it was definitely happy to see me!


Here's a close-up of the ribbon of sperm emerging from this guy's amorous head. Poor cuke, it was all alone, there were no other members his species spawning near him. Lack of proximity to spawning females means that there are no eggs in the water, and he's probably just wasting his wild oats. I patted his sorry head and consoled him, "sorry dude, but don't be so sad - there's no use crying over over spilled leche!"

Spotted Eagle Ray!

As I was snorkelling near Piti Channel at sunset today, I saw a spotted eagle ray (Aetobatus narinari)!!! It had its "snout" in the sand - probably looking for mollusks or crustaceans or sea urchins to feed on. I wish I had a better photo, but I didn't have time to take a decent pic before it spotted me & moved away. Very exciting moment, I almost forgot to breathe!