Ostra-blog 7 - Trapping ostracods

Some ostracods are attracted to traps, namely bait traps and light traps. My first experience with ostracod trapping came in 1998, during my trip to Japan (see ostrablog-5) as a graduate student intern.

My Japanese host, Katsumi Abe took me, along with members of his lab to his "mountain home", near Tateyama. Abe's mountain home was a geodesic dome, mostly without walls on the inside, except for the bathroom (complete with remote-controlled toilet), which thankfully had walls. This mountain home seemed to be designed as a well spring for creativity: puzzles, games, and books littered the structure. I remember signing the guest book, and writing a Haiku, inspired by the well spring, and by the beautifully wooded and mountainous surroundings. My lab mates and Abe's son constructed flutes from bamboo growing outside.

In nearby Tateyama, there is a pier, and this is a very famous place to catch "umihotaru", which translates to "sea fireflies" - the scientific name is Vargula hilgendorfii, an ostracod. This animal is a scavenger. At sunset and later, they rise from the bottom, where they rest all day, and follow the scent of dead flesh to find and feast on fresh carcasses. We can take advantage of this behavior and design traps to attract umihotaru. In Tateyama at this pier, the animals come to the traps by the thousands.

We arrived at the pier just before sunset. Professor Abe was a celebrity there. Meeting us were a class of high school students and several members of a biochemistry lab, who study the light producing chemistry of umihotaru. Abe walked the pier proudly. Many people came up to him asking him questions, bowing deeply. The show was about to begin.

We placed traps in the water; glass jars with holes drilled through the lids. Inside, we placed pig liver, which attracted the umihotaru nicely. After leaving the traps in the water for 20 or so minutes, we pulled up the ropes, and dumped the contents into an aquarium net to separate ostracod from liver and from water. When the ostracods hit the net, they were disturbed, and when they are disturbed, the produce their intense blue light. The light producing chemicals mixed with the sea water, and cascaded down on to the pier, through the planks, and back into the ocean. The biochemistry lab was thinking big. They came from far away in Japan, and needed a large haul of umihotaru to support their studies for a while. They had many traps, and one after the other, they emptied animals into a square container, perhaps 2feet wide by 3 feet long by 2 feet deep. By the end of the night, this container was half full with ostracods; thousands upon thousands of them.

The night felt festive. Enthusiastic students were asking questions, and marveling at the light show. I felt a part of this community. Despite my knowing very little Japanese, I felt I understood a lot from context, from body language. By that time I had also built a language with my lab mates - I'd learned which English words they knew, and which phrases and verb tenses to avoid because they caused confusion. I remember naturally answering someone excitedly in the affirmative with "so so so so", as I'd often heard the Japanese do, and this came naturally to me. Caught up in the festiveness, I decided it would be fun to eat some umihotaru. The ostracods tasted like .... seawater. My mouth glowed with the bright blue light we'd watched cascading down the pier all night. I'm quite certain the students thought me a crazy "gaijin", and they were happy to laugh and talk excitedly among themselves, and my mouth continued to glow.

I have some video of trapping umihotaru, taken at this very pier. This video is from a Japanese science documentary that featured Abe's lab. I copied the VHS tape while there, and I moved some parts to computer a while back (I also sped up the video a little, so I could show it in seminars and not take too much time):






Since my first introduction to trapping ostracods, I've designed my own traps. These are cheaper, lighter, and safer to transport than glass jars. Since I'm working on an invited book chapter on how to collect ostracods, I've made a figure describing my design. Perhaps you want to try to trap ostracods where you live:


Figure 1 - a. Inexpensive 50 ml conical tubes are available from many vendors, and are nearly ubiquitous in labs conducting molecular biology. b. The first step is to saw the end off of the tube, above the conical portion c. a hole is drilled in the bottom of the cone. The size of the hole can be varied; only animals that fit through this hole will be trapped. d. The cap is removed, and the cone-end is placed in the opening. Friction holds the cone tightly in place. e. Bait (such as imitation crab meat made of pollack) is placed in the tube, and the open, sawed end is covered with material (such as that cut from an old t-shirt), and secured with a rubber band. Numerous traps can be secured to nylon rope with plastic zip ties.

Ostrablog 5 - Three shows and a funeral

In 1998, I spent nine weeks in Japan in an international graduate student program co-sponsored by the National Science Foundation of the United States and the Japanese ministry of Science, Monbusho. The trip was for me a memorable and life-changing experience I many ways. Besides a high school trip to Mexico, Japan was my first trip abroad, and the magnitude of cultural differences between the US and Japan was a big part of the memories. For me, immersion in a different culture is mind-stretching. If you haven’t been to Japan and want to get a sense of what I mean, I found the film Lost In Translation to be quite a good [although decidedly amplified and somewhat stereotyped] facsimile of total immersion in the culture. Besides culture shock, another vivid memory of my Japan trip involves the subject of today’s ostra-blog, the ostracod Vargula hilgendorfii.

Vargula hilgendorfii. Male on top female on bottom. Image from umiho.net

Vargula hilgendorfii is known to the Japanese as ‘umihotaru’. “Umi” means “sea” and “hotaru” means "firefly". Umihotaru are vividly, potently, bioluminescent. When threatened, they spit out a liquid cloud of light that is the blue of a sun-drenched Caribbean bay. The animal is only about 2 mm in length, roughly the size and shape of a sesame seed. Yet the “light bomb” (as one of my Japanese friends called it) can be seen from meters away. To detonate this bomb, umihotaru spits out an enzyme and its substrate from glands on its “upper lip”, an organ just above its mouth that also spits out digestive enzymes. My Japanese advisor and host, Katsumi Abe, had the idea that the light producing enzyme is actually derived from a digestive enzyme, and evolutionary novelty that arose by duplication and divergence. It was hundreds of light-vomiting umihotaru that provided one of my most potent, and decidedly surreal memories of my Japanese adventure.

Light from the ostracods of the species Vargula hilgendorfii. Image from http://www.kanko-otakara.jp

Imagine a nearly full sheet of plywood (4 x 8 feet) standing in the back of the room. Attached to the plywood are rows and rows of vials filled with seawater. The vials are capped and through each cap runs two thin wires, dipping into the water. The wires all bundle together behind the plywood and snake back to a console. The console looks like a mixing board at a rock concert, with a row of sliders. The consoled is plugged into an electrical outlet in the wall so that the wires can deliver a potentiated jolt of electricity to the vials of sea water. I would soon find out that swimming in the numerous vials of seawater, were hundreds of ostracods, umihotaru.

While I examined this strange contraption, trying to imagine the purpose, the room lights when dark, and cheesy, achingly theatrical, synthesized new age music filled the room. An operator took his position behind the electric console, leaning forward with his hands on the sliders like a rock star keyboard player. He dexterously began moving the sliders in time with the music, sending pulses of electricity into the bodies of the umihotaru. They felt threatened, and they were vomiting their luciferase enzymes into the vials of brine, producing effervescent azure explosions of light, pulsing in time with the music.

The vials were not the only part of the show. Hidden behind curtains, the electric console-wielding front man had assistants. Poised precariously on top of a step ladders, their instruments were funnels aquarium nets and buckets of water. Inside the nets? Hundreds more umihotaru! Precisely choreographed with the music, the assistants vigorously poured water into the nets of umihotaru. Too large to pass through the nets, the water coursing over them threatens them until they spit out their light, illuminating the coursing water. The water cascaded into the funnels, which were directly attached to clear aquarium tubing. The tubing ran the length of the room, 30 feet at least, descending and arcing gracefully like garland at Christmas time. The water stayed lit on its journey through the tubes, the entire length of the room. The same electric blue that pulsed in the vials punctuated cymbal crashes by coursing through the tubing.

As if that weren’t enough, umihotaru was on display in one more way. Larger clear tubing hung in “U” shapes in a few places in the room. One each side of the U, wires ran, connecting back to the electric console. These larger tubes stayed filled with seawater, and again, umihotaru swam in the water. Dedicated sliders jolted the U with electricity, and umihotaru swam, leaving behind illuminated contrails, like tiny psychedelic fighter jets – and again choreographed to the blaring music.

I’ve told this story many times, and depending on my mood, and how well I know the listeners, I will sometimes stop here. People laugh incredulously, ask a question or two, and we move on to other stories. Because the story takes a more somber turn here, I often leave out the most unbelievable part of the story. The kitchy, surreal display I just described actually began the funeral of my Japanese advisor Katsumi Abe. People even took pictures and video. Of a funeral.

A week earlier, Abe was tragically killed when his car struck an oncoming truck head on. He was young, in his mid-40s I suppose, full of energy, full of life. He had five children. I was one of the last people to see him alive. He left a conference that we were at late at night. He probably fell asleep at the wheel and never woke up. I felt so alone in that foreign land without my host and I felt guilty for feeling alone. What right did I have to feel bad, compared to five children who lost their dad, or to a wife who lost her husband? The night after the funeral, I had to go to Tokyo. My plane was scheduled to leave the next day. Fitting my mood, a torrential storm from a typhoon drenched me while I waited for trains with a Japanese friend who kindly escorted me. He also was at the funeral and knew Abe well. A few days later, I would be a world away in sunny Bermuda to collect other ostracods. But no matter the distance I travel, I will never forget Japan. Abe wrote a book in Japanese which translates to "The Light of the Marine Firefly". Whenever I see that electric blue light, I think of him.