Photohunter: Ruined

I was going to post something else, but a quick look outside my window changed my mind. This was taken at 2:30 pm. Right now, Southern CA is being hammered by wildfires. A little to the north of me, there are some major fires going on and many people are being evacuated. Needless to say, our air quality is ruined as well.

Life Photo Meme: Secret

What is the secret behind the demise of this coral? I don't know for sure, but I can make a pretty good guess based on the picture. Can you?

It looks like this coral has been the victim of that famous corallivore, the crown of thorns starfish (Acanthaster sp.). You can see part of the culprit in the center bottom of the picture. What looks like a patch of grey, red-tipped spines is actually the starfish. The crown of thorns is infamous for eating corals. They crawl on top and digest the fleshy parts, leaving the stripped white skeleton of the coral behind. Their spines are also a painful irritant to humans.

The crown of thorns is distributed throughout the indo-pacific, and has been thought to consist of single species, Acanthaster planci. However recent molecular evidence suggests that there are actually four species of Acanthaster [1].

This coral-eating starfish can devastate reefs when they appear in high numbers, but there is hope from a coral eating starfish.

Kingdom: Animalia

Phylum: Echinodermata

Class: Asteroidea

Order: Spinulosida

Family: Acanthasteridae

Mussels on the Move

Mussels can be a dominate organism in many rocky intertidal communities. Unlike other permanent residents, like barnacles and algae that are permanently attached to the rocks, mussels can move short distances by creating byssal threads. The byssal threads are primarily used as a means of attachment, but by creating and attaching new byssal threads and cutting lose from old ones, mussels can pull themselves along rocky shores.

People who walk around in the intertidal may notice, like the authors of a cool article featured in Science, that mussels often cluster in interesting patterns on the rocks. The authors found that the size of the clusters and the pattern of the clusters is consistent among mussel beds (with similar mussel densities), set out to determine why.

They found that if you spread mussels out evenly in the laboratory, they will spontaneously form clusters similar to those seen in the field, even in the absence of the rocky substratum and wave action found in the field. They also found that if you place mussels in various-sized clusters at the start, there is a difference in movement based on initial cluster size. Mussels in small clusters (with 2-8 individuals) and mussels in large clusters (with 128 individuals) tended to move around and rearrange themselves a lot more than medium size clusters. So, mussels really want to be in a cluster of a certain size... but why?

Large clusters have may have a food limitation. With all of their neighbors filter feeding, having to many individuals around you may limit the amount of food you can capture. When the authors squirted food in the middle of large clusters, the individual mussels were pretty content to stay in the large cluster. But if clustering reduces food, why cluster? When placed back out in the field, individuals who were not in a cluster were more likely to be knocked off by wave action.

So, individual mussel will gather together in a cluster, but when the neighborhood gets too crowded they move. By arranging themselves in the rather interesting maze-like pattern of clusters and spaces often seen in the intertidal, individuals get protection from wave action, and have a higher growth rate than densely-packed mussel beds.

Van de Koppel, J., J. Gascoigne, G. Theraulaz, M. Rietkerk, M. Mooij, and P. Herman. 2008. Experimental evidence for spatial self-organization and its emergent effects in mussel bed ecosystems. Science. 322:739-742.

Photohunter: Together

(No on prop 8 post-election rally)

I was going to do a post on colonial organisms for this week's together post, but given what has been happening here in my home state, I thought I'd hijack my own blog and talk about something more political this week.

As you all know, three states have passed bans on gay marriage this election cycle. I am most disappointed in California, which recently allowed gay marriages, and where I have been listening to very weak arguments for this ban. First off, why is this an issue? CA does have a very good civil union package which offers most of the rights and responsibilities that married have, but these unions are not recognized in many of the other states or by the federal government. A marriage performed in one state is recognized in other states. "Marriage" as a secular term does not (or did not) include a religious aspect, people can get their marriage officiated by whoever they want, but cannot force someone (or a church) to officiate. So offering marriage to same-sex couples does not change anything for different-sex couples, but does allow same-sex couples to stay married if they move and paves the way for federal benefits/taxes to be given to same-sex couples.

(Parents of gay children show support in a gay pride parade)

Protecting "traditional marriage" is a poor excuse to refuse same-sex marriages. Just because something has "always" been done this way does not make it right to continue to deny a minority's rights. Of course, marriage has NOT "always" been done this way. Marriage was about transfer of property (cows/land for women to establish bloodlines), which meant it could be between one man and several women. Currently, marriage is about two people deciding to pool their financial and physical resources to set up a household together, and formalizing that agreement through governmental records.

(Me and my spouse after our civil wedding)

I am very ashamed for this state, in which the narrow majority has decided to strip a minority of legal rights, and codify that bigotry in the state's constitution. Saying it's the will of the people does not excuse it. An unpopular minority cannot expect that the majority will look after its rights. Until a short while ago (1958), the majority disavowed marrying people of differing races. I hope that soon, I will be able to express the same disbelief that marrying people of the same gender was ever an issue.

Life photo meme: Mystery Sacoglossan

Kingdom: Animalia

Phylum: Mollusca

Class: Gastropoda

Order: Sacoglossa

Family: Hermaeidae

I recently went on a collecting trip up the coast, and there were hundreds of these sea slugs wandering around on the mud flats we were at. They are really small (my hand is the background in the picture), and the trip leader could not identify them. I took a quick picture and they took a egg mass back with them, to try and ID these slugs. I asked a friend who works with sea slugs and she tentatively identified them as an Aplysiopsis species. Interestingly, she had gone on a trip farther north, and seen hundreds of these as well. So they seemed to be blooming all along the central/northern part of the coast.

Alas, we won't truly know what species it is unless we look at its radula and penis, two of the main features used to distinguish different sea slugs. But this little adventure has allowed me to get some fun footage of mystery slug veliger larvae! This larval type is characteristic of gastropods, and if you look at them you will notice that as larvae, they all have shells. The shell is lost in the adult sea slug.

Without further ado...