Nudibranchs defend themselves with their food

Nudibranchs, or sea slugs, are descended from animals with protective shells like those of modern snails. Nudibranchs have lost that shell, leaving them potentially vulnerable: squishy morsels in an ocean full of hungry things. But nudibranchs have some tricks to avoid becoming someone else’s meal: they use their own food to protect themselves.

Hermissenda crassicornis may not have a shell, but he is well-defended. Photo by M. LaBarbera

Hermissenda crassicornis may not have a shell, but he is well-defended.
Photo by M. LaBarbera

One trick is to steal the defenses of your prey. Many nudibranchs eat stinging animals like hydroids and anemones. These animals use specialized stinging cells to catch their own prey and to defend themselves.

Hydroids. The stinging cells are on the ends of the long tentacles, waiting to catch prey. Photo by M. LaBarbera

Hydroids. The stinging cells are on the ends of the long tentacles, waiting to catch prey.
Photo by M. LaBarbera

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Velella velella! Or, falling off the edge of the world

They were strewn all along the beach, these transparent, tripartite things. At first glance they looked like plastic trash, but they felt organic in my fingers.

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Fortunately I happened to be beachcombing with a world expert on marine invertebrates. “Ooh,” he said, “Velella!”

Velella velella, or by-the-wind sailor: a living sailboat, a jellyfish on a stiff frame. In their preferred state, i.e. when not washed up on beaches, these animals float on the ocean surface with their tentacles just below the water, to catch food, and their upright sails above the water, to catch the wind.

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Seeing through scales and walking with six legs

There are a lot of scientific journals out there. There are the big shots (Science, Nature), the bird journals (The Auk, The Condor), the topic-specific (Behavioral Ecology), etc. And then there is The Journal of Experimental Biology, or JEB. I love JEB. It claims to be the journal for “comparative animal physiology” but that doesn’t cover the half of it. JEB is about crazy, wonderful strangeness—strange animals and strange scientific methods. Following are two characteristically odd JEB studies: snake eyes and how walking sticks walk.

Leucistic (lacking pigment) black rat snake is looking at YOU.

Leucistic (lacking pigment) black rat snake is looking at YOU.

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Featured paper: cuttlefish are lying cheaters

Although the cuttlefish may be best known for making those flat cuttlefish bones that your pet bird nibbles to get calcium, this paper shows that it should be known for being a lying cheater.

That was uncalled for. Photo by Tom Olliver

That was uncalled for.
Photo by Tom Olliver

Cuttlefish, like their relatives the squids and the octopuses, are masters of visual communication. They can change their appearance almost instantaneously (video here), and they use color and pattern to say things like “Back off, I’m angry!” and “Pretty lady, I would like to do some romance with you now,” and “Please don’t do romance with me, I am male.”

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The slow, slimy style of snails

It doesn’t rain very often here, but when it does, the snails come out in force. I’ve always liked snails and their ilk; as a kid I kept slugs as pets. Unfortunately I think the snails here are brown garden snails, an invasive species.

snails1Sinister invaders or not, like any snails they’re surprisingly engaging to watch. Bumpy skin, patterned shells, eyes on stalks, and total flexibility give a lot of opportunities for expression.

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Non-birds of the field I: invertebrates

From most of the pictures on this blog, you might think that the only animals we saw this summer were the ones that flew into our nets. Not so!

Big red fuzzy moth

Of course, whether I can identify these non-birds is a different matter entirely. If you see anything you recognize, please comment and let me know what these exoskeleton-clad creatures are.

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