Category: biology

Whale Fall

Following the discovery of a new, natural whale fall in Antarctica (announced Wednesday), I entertained a brief obsession with marine snow and the communities that build up around whale falls. It is amazing how a whale carcass can support such a totally unique and vibrant community for 70 years or more. Of course it makes sense; since the sea floor is such a low-energy zone and there is a lot of food to be had on a whale.

This 7 million year old grey whale rib probably never contributed to a whale fall community, because it got fossilized instead of getting eaten (found at Point Reyes, Northern California)

Whale falls are incredibly difficult to find, because you must stumble upon the site of a whale carcass on the ocean floor entirely by chance.  The deep sea floor is incredibly difficult to explore, and so the chances of finding a felled whale carcass get lower and lower the deeper it sinks. This is why most of what we know about whale fall communities come from “artificial” whale falls, or whale carcasses which scientists sink and then study the progression of the community which arises.

Continue reading “Whale Fall”

The Dangers of Phase Contrast Microscopy

“Every time that the person before me left the scope in phase 3, and I forgot to check.”

This honestly happens to me far too frequently, you’d think I would learn to avoid it or something. I’m just going to say that I get so excited to see my little bacteria under the scope, that I can’t help myself and shove my eyes into the eyepieces as fast as possible. I mean, some of these guys have week-long doubling times!

The Photosynthetic Sea Slugs, and Horizontal Gene Transfer

The sea slugs known as Elysia chlorotica are certainly a strong contender for my favourite animal.  They are born clear, and they feed on algae for nutrients and energy.  But, they poke little holes in the turgid algae pieces with their tooth, and suck out the individual chloroplasts.  The chloroplasts do not get digested, and instead migrate to the animal’s skin, where the animal has gained the ability to keep the chloroplasts alive inside its animal cells (not in-between, but inside).  The chloroplasts then photosynthesize using sunlight, and produce energy for the slug’s cells.  The chloroplasts make the slug’s skin green, and indeed the slug has evolved to take on a shape which maximizes surface area, in order to harvest as much sunlight as possible.  The adults resemble leaves for this reason!

Watch this video of the little guy sucking out the chloroplasts from a piece of algae:


These slugs were successfully kept alive in excess of a year in a tank with absolutely no caloric input in the water, and with nothing but a UV “grow lamp.”  Their growth was very slow during this time, but this indicates that an animal was capable of living entirely off of photosynthesis!  This is the only animal known to be capable of keeping the chloroplast endosymbiont alive. Continue reading “The Photosynthetic Sea Slugs, and Horizontal Gene Transfer”