Monthly Archives: July 2012

Sea Hare Ink Makes Lobsters See Purple

By Vladimir Brezina

This week’s Photo Challenge has got me thinking about the color Purple.

The most vivid purple that I’ve ever seen was not the purple of flowers, nor of sunsets. Rather, I see it in my lab. One of the experimental animals we work with is a large marine slug from California, Aplysia californica, popularly known as the sea hare. When disturbed, the sea hare releases a cloud of ink that has the most intense, rich purple color.

Those of a classical bent will recall Tyrian Purple, also known as Royal or Imperial Purple, a dye greatly prized in antiquity, which was made from a similar ink produced by several Mediterranean snail species:

Tyrian Purple was expensive: the 4th-century-BC historian Theopompus reported, “Purple for dyes fetched its weight in silver at Colophon” in Asia Minor. The expense meant that purple-dyed textiles became status symbols, and early sumptuary laws restricted their uses. The production of Tyrian purple was tightly controlled in Byzantium and was subsidized by the imperial court, which restricted its use for the colouring of imperial silks…

Interestingly, the purple color of the sea hare’s ink, as well as the purple tinge of its skin, actually derives from its preferred diet of red seaweed. If sea hares in the lab are fed green seaweed, their skin eventually turns green. I wonder if they then release green ink?

What is the biological function of the ink? We all know about squid, which release a dense cloud of ink (black in that case) into which they quickly vanish when danger threatens. But sea hares, despite their name, are sluggish. Their ink cloud is sparse to begin with, and when it disperses, the sea hare is still there.

It turns out, however, that the ink, together with other secretions that are released at the same time, provides a chemical, rather than a visual, defense. A 2005 paper by Kicklighter et al. analyzed the chemical composition of the secretions and their effect on attacking predators such as spiny lobsters. The secretions contain a complex mix of chemicals that elicit multiple, conflicting behaviors in the lobster. Indeed, while some of the chemicals are aversive, as one might expect, others actually stimulate lobster feeding behavior and mimic a food source.  The result is that the lobster is not just coated with sticky goo and repelled, but, if it persists, it is diverted to attack a phantom food stimulus—the inky cloud—while the real food item slips, slowly, away:

In multiple such sea hare–lobster pairings, Kicklighter et al. found that, if the sea hare was allowed to release its defensive secretions, it escaped from the lobster 60% of the time. But if it had had its secretory glands removed, it escaped only 19% of the time—most of the time, without its chemical defenses, it was eaten.

Kicklighter CE, Shabani S, Johnson PM, Derby CD. Sea hares use novel antipredatory chemical defenses. Current Biology 15:549-554, 2005.

Long Island Kayak Circumnavigation: Day 3—Along Fire Island

By Johna Till Johnson and Vladimir Brezina

<— Previous: Day 2

Fire Islands to Moriches Inlet
18 nautical miles (21 land miles)


(click on photos to expand them—they look a lot better when they’re BIGGER!)

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Weekly Photo Challenge: Purple

By Vladimir Brezina

This week’s Photo Challenge is Purple.

Purple is a color created by mixing red and blue. So there is a range of purples, depending on how much red and how much blue you mix together.

And the entire range of purples can be seen simultaneously at sunrise or sunset, as the red tinge of the rising or setting sun infuses the blue of the sky…

All from our recent Long Island Kayak Circumnavigation.

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Long Island Kayak Circumnavigation: Day 2—Jones Inlet to the Fire Islands

By Johna Till Johnson and Vladimir Brezina

<— Previous: Day 1

Jones Inlet to the Fire Islands
20 nautical miles (23 land miles)

(click on photos to expand them—they look a lot better when they’re BIGGER!)

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Weekly Photo Challenge: Inside, Take Two

By Vladimir Brezina

This week’s Photo Challenge is Inside. I’ve already posted one response to this challenge, but here’s another one.

The view from inside as the day begins…

Inspired by our recent adventures on Long Island.

Weekly Photo Challenge: Inside

By Vladimir Brezina

This week’s Photo Challenge is Inside.

What’s inside?

More photos are here and here. And here is a second take on “Inside”.

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Long Island Kayak Circumnavigation: Day 1—Off to The Rockaways!

By Johna Till Johnson and Vladimir Brezina

<– Previous: Prelude

Pier 40, Manhattan to Jones Inlet
32 nautical miles (37 land miles)


(click on photos to expand them—they look a lot better when they’re BIGGER!)

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Weekly Photo Challenge: Dreaming

By Vladimir Brezina

This week’s Photo Challenge is Dreaming.

Dream of ducks, duck dream, ducks dreaming, dreamy ducks…

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Long Island Kayak Circumnavigation: Prelude

By Johna Till Johnson and Vladimir Brezina

Ready to launch into adventure

On the morning of Wednesday, June 27, 2012, we found ourselves standing on Pier 40 in Lower Manhattan ready—we hoped!—to circumnavigate Long Island by kayak.

After paddling down the Hudson River last year, the Long Island circumnavigation seemed to be our next logical expedition. At roughly 230 nautical miles (265 land miles), it was twice as long, but not too ambitious. We estimated that it would take 11 days or so. And we loved the idea of simply taking a cab down to Pier 40, launching our kayaks and paddling round Long Island, and then taking a cab home upon our return.

The basic plan

But, although we’d spent months dreaming about the trip, we came down to the wire when it came to planning it in concrete detail.

The week prior to launch passed in a blur of sleepless nights, with mileage and tide calculations, electronics purchases on Amazon, food shopping, and last-minute trips to REI for camping necessities, all slotted in between the heavy work obligations that always seem to accumulate at such times. We bought tons of food: coffee, rice and oats, packages of dried fruit and nuts, apples and oranges, salami and cheese, vacuum-packed salmon—as it turned out, way too much. We pored over the charts and circled likely campsites, made reservations for places to stay, then cancelled some of them again.

Then there were the fears. Johna worried about things like unfriendly locals, and sharks. (In case that seems nuts, check out this article, from just a year ago, or this one, which fortunately appeared only after our return. Eighteen-foot sharks—Yikes!)

Vlad was no help when it came to allaying the fears. “Hmm,” he said thoughtfully. “We should rent ‘Deliverance’. And ‘Jaws’.” As it so happens, both made an appearance of sorts on the trip. And we were attacked during the 35-mile run up the South Shore—but in no way we had possibly anticipated.

On Monday, when we had originally planned to launch, we still weren’t ready. Nor on Tuesday. But by 3:30 AM on Wednesday we were up and readying to go. The plan was to leave at 5:00, and launch about 6:30 or 7:00 AM.

Johna ready to go!

We almost didn’t make it. Johna was putting the finishing touches on a work project, and as a result we didn’t leave for the pier until 5:25, with Vlad fretting that we’d miss the currents. In the cab on the way there, Johna had a panic attack when it appeared her project hadn’t uploaded, and Vlad suggested we turn around and launch Thursday. But after so much preparation, delaying another day didn’t seem right. (Johna’s work project made it through just fine, as it turned out).

Vlad ready to go!

With no traffic, by 6:15 AM we had arrived at Pier 40. Fortunately we had already packed most items into the kayaks on the previous day. But we still had to somehow fit in all our drinking water. (The loaded boats were then so heavy that we could hardly drag them to the water, a foretaste of things to come.) So it took us until 8:00 AM—almost the last moment to catch the ebb current that we would need to make it out of the harbor—to get ready, finally, to set off on our big adventure.

In subsequent posts, we will describe each day of the trip in sequence. And for fellow paddlers thinking about this or a similar trip, we’ll add a Postcript: Lessons Learned with more logistical details.

Next: Day 1 —>

Travel Theme: Night

By Vladimir Brezina

Over on Where’s my backpack?, Ailsa has posted this week’s theme for her Travel Photo Challenge: Night.

Every now and again I travel for work to San Juan, Puerto Rico, where I stay in the old town. The heat is unbearable and the air conditioning is spotty. But toward evening, as the air cools, I walk through the town. Invariably I end up on the esplanade, the vast grassy open space that separates the town from the Castillo San Felipe del Morro, the old Spanish fortress that from a high promontory overlooks the town and the harbor. Many others are there to watch the sunset, to fly kites in the ever-present breeze, and to enjoy the soft night air. I randomly wander through the open space or just lie down in the grass under the darkening sky…