You can't vaccinate an octopus

In a piece on octopus farming, Katherine Harmon mentions a fascinating fact — octopuses don't have an adaptive immune system, the handy-dandy network of different immune-response cells that allow us vertebrates to more easily fight off infections our bodies have encountered before.

That's a problem if you're trying to raise a bunch of invertebrates in close quarters (as per a farm) because you can't immunize them against pathogens that could easily spread from one octopus to another. As a random biological tidbit, though, it's just damned fascinating. Check out this doctoral thesis for more information on how the octopus immune system does work. You should also read this story that looks at the evolution of the adaptive immune system and asks a key question — does having immune "memory" really make us that much better off than the animals that don't have it?

Image: Octopus, a Creative Commons Attribution Share-Alike (2.0) image from alicecai's photostream

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When the octopus says, "ouch"

Given that people are going around doing things like cutting off octopus limbs in order to understand their distributed neuron processing system, it's worth asking some questions about how octopuses perceive pain, as well. That's more complicated than you might think. As Katherine Harmon explains, it's likely that octopuses have some kind of awareness of when they're touching something unpleasant. But just how that works, and how similar it might be to the way we vertebrates understand "pain", is a big mystery. Read the rest
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Sucking up to shrimp

Say you're a marine biologist and you want to study the little bitty creatures of the sea — shrimps and worms and things like that. How do you go about capturing them?

Why, with an underwater vacuum, of course.

At the PNAS First Look blog, David Harris writes that this "SCUBA-tank powered vacuum, called an “airlift,” inhales shrimp, sand fleas, marine worms, and 'things that would swim away if they had the chance.'" Read the rest

The business end of a sea urchin

How's this for an amusing case of photographic mis-identification? Call it "Dueling Disgustingness". Last week, New Scientist posted this lovely image of a blue-spotted sea urchin, taken by nature photographer David Fleetham.

New Scientist identified the photo as depicting said sea urchin in the process of expelling its own guts out of its mouth. Which, gross, but okay. That's reasonable. A surprising number of underwater animals eat in this manner, using the acids in their guts to dissolve prey before they actually slurp it up as a slurry.

But, at the Echinoblog, Smithsonian invertebrate zoology researcher Christopher Mah makes a compelling case against New Scientist's interpretation. That's not actually the sea urchin's mouth, says Mah. In fact, it's the opposite. That's a (rare) photo of a sea urchin taking a dump.

Mah has a lot of good photos that make his case quite well. You should check them out. Then, join me in contemplating this thought: If Mah is right, doesn't sea urchin poop look a lot like Dippin' Dots?

The New Scientist blog post—featuring lots of cool info about sea urchins

Christopher Mah's analysis of the photo, explaining why he thinks it shows a pooping sea urchin, rather than one that is eating something.

David Fleetham's website—for more (less disgusting) photos of nature

Via Scicurious

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Tool-using animals: Now with 100% more invertebrates!

Warning: This video contains footage of an octopus hiding under a coconut shell that it has carried around just in case it needed to hide from something. Watching this footage may contradict your previous assumptions about animal tool use, and may be too adorable for some viewers.

National Geographic: Octopuses Carry Coconut Shells as Instant Shelters Read the rest