Ostra-blog 9. Postasterope barnesi

It's unfortunately been too long since I've posted an 'ostra-blog', a post about my main study group, the Ostracoda. If you haven't seen these, I encourage you to read some of them. Most contain little anecdotes, personal vignettes about interesting experiences I've had with ostracods.

Try this link, if you interested.

This installment is a quick post inspired by a colleague who is trying to collect bioluminescent Vargula (subject of previous posts). He did some plankton tows out by Catalina Island, and came up with some ostracods, but these are a different family. See our exchange below, and a picture sent by his student:


The query:
Hi Todd,

I apologize for the out of focus, low magnification photo attached -- but is it likely that these ostracods are Vargula tsuji? These are not from a trap, but instead from night surface plankton tows from the dock at Wrigley. These are quite large for ostracods (up to 1.5 mm or so in length, I'd guess), fairly bright orange, and very abundant in the plankton soon after dusk.

Thanks for any simple confirmation/rejection of our tentative id. I appreciate it. Sorry again for the low quality image; I'm not at Catalina or I'd take a better one. This was sent to me by a student.



The Picture:



The reply:

No, those are not Vargula, which is in the family cypridindiae. These that you found are in the family cylindroleberididae. I think the common sp out at Catalina is Postasterope barnesi, and this looks like it could be that species. Both are myodocopids, which are larger than the somewhat more common podocopids...

I've found males of this family to be attracted to lights at night. Most myodocopids mate in the water column after sunset, and the males of some sp are attracted to lights. Probably just about all the individuals they found are males, I'd guess. The one pictured looks like a male, based on the tapered carapace (hard for someone to see who hasn't looked at a million ostracods). But an easy way to tell a male in these is that the males have a REALLY long sensory bristle. It's a "hair" (2 actually, one on each side) that emerges from the front of the carapace along with the swimming appendages. But this sensory "hair" is really long, longer than the body in many cases. I actually can't tell from this picture if there are the long sensory bristles because of the focus, but I'll bet they are there... I do see a white line across the carapace in the right spot, but I can't tell if that is part of the swimming appendage, or the sensory bristle....

Ostra-blog - Euphilomedes morini

Male eyes Apollo, Nyx the female eyes

Stearn’s Wharf, the landmark wooden pier that effectively extends Santa Barbara’s main drag of State Street 1900 feet into the Pacific, is usually crowded with sightseers, diners, and fishermen; locals and tourists alike. Yet, unless they enter the Sea Center, probably very few of the visitors to the wharf stop and consider what is living just meters below the wooden pier where they walk. The ostracod crustacean species Euphilomedes morini is one of these denizens of the not-so-deep, and because of its distinctive eyes, it is an object of scientific study within the Cheadle Center for Biodiversity and Ecological Restoration at the University of California-Santa Barbara. Euphilomedes morini males have compound eyes that would make proud Apollo, the Greek God of light. But females lack these eyes, nixed not by the Goddess of night (Nyx), but by evolution and development.

Fig. 1 - Stearn's Wharf, Santa Barbara, CA

Class Ostracoda

Before discussing E. morini and its eyes, I will first introduce the class of animals to which the species belongs, Ostracoda, the ostracod crustaceans. Ostracods are small and ancient crustaceans, usually the size of sesame seeds or smaller. Sometimes known as “seed shrimp”, they make their debut in the fossil record in deposits of Ordovician Age, rocks that are some 450 million years old. Following this ancient appearance, ostracods are notoriously abundant in the fossil record. In some places, ostracod density can reach up to several thousand individuals per 100 g (3.5 oz) rock mass!

In addition to the estimated 30,000 different fossil ostracod species, some 15,000 species are alive today. But only roughly half of these living ostracods are known to science (have official scientific names). On one research expedition to a marine lab in Puerto Rico, I dipped a bucket in the ocean and chanced to find an unknown species, which we later named Euphilomedes chupacabra. This was on the pier of the marine lab, where hundreds of marine biologists have walked, and where their boats are docked. If unknown species live here, imagine what remains to be discovered in the farthest depths of the oceans, or the remotest ponds and pools. Even the subject of this piece, E. morini was first named as recently as 1997, after Jim Morin, an ostracodologist who has contributed much to our knowledge of the “fireflies of the sea”, a family of ostracods whose males produce brilliant blue light flashes to attract females (those females have eyes).

Ostracods are not confined to oceans. They live almost anywhere there is water. The small temporary ponds (vernal pools) that fill with California’s winter rains are home to hundreds of ostracod species. Life stages are resistant to drying over California’s long and often rainless summers. On a hike in the foothills above Montecito one winter, I once found a crevice in a boulder that had filled with rain water. To my surprise, that tiny bit of water teemed with ostracods. These animals also live in the water filled cups of bromeliad flowers, and some species even live without standing water, for example in the damp leaf litter of Australian rainforests, and just above the tides in the United Kingdom.

Not surprisingly, given the diversity of habitats occupied by ostracods, different species make a living in a wide variety of different ways. Some ostracods are scavengers. Others are predators, like the “giant” deep sea ostracod, Gigantocypris. Almost the size of a ping pong ball, Gigantocypris uses large silvery reflectors to focus light on its tiny retina and track down prey like plankton and even small fishes. Many ostracods are “deposit feeders”, feeding indiscriminately on organic matter found on the bottom of oceans or lakes.

Like the common housefly, ostracods are arthropods. Both houseflies and some ostracods see the world using compound eyes. Unlike our own eyes, which focus light through a single lens like a camera, compound eyes sample light through many lenses each a part of a separate facet called an ommatidium. Housefly compound eyes have hundreds of facets, while ostracod eyes have at most about 60, but usually fewer. Interestingly most living ostracods lack compound eyes, but some have them.

Euphilomedes morini

Although many ostracod species live locally, one in particular has been the subject of research in our lab for two reasons. First, E. morini is quite common and easily collected from Stearn’s Wharf or Goleta Pier. We simply drop a grab-sampler into the the water and bring up a bit of sand from the bottom of the Pacific. E. morini is one of the commonest animals of its size (~1 mm) in the shallow waters of the California coast. Second, E. morini has an interesting feature: Males have large compound eyes, but females do not.

Figure 2 (A, B) Lateral view of adult animals with half of carapace removed. Anterior is to the left. One lateral eye is visible (arrows). The female eye (A) is small and rudimentary without ommatidia and is only faintly pigmented. The male eye (B) is much larger, dominating the head of the animal with clearly visible ommatidia and a small rudiment (arrowhead) (C, D, E). Lateral view of instar IV male eyes from Euphilomedes longiseta (C) and Euphilomedes morini (D) and instar V Euphilomedes carcharodonta. Arrowheads denote rudiments. Stage matched lateral eyes from these three species are indistinguishable. Panel (E) depicts the development of a male compound eye. Pigment was photobleached under UV to allow a better view of the morphology. All rudiment pigmentation was removed in the photobleaching. The largest lenses and darkest pigmentation are at the distal end of the ommatidial field. Growth appears to occur in the direction of the curved arrow, as suggested by the presence of smaller lenses and fainter pigmentation. A putative morphogenic front is marked with a red arrowhead. (F, G) Eyes of late stage embryos (carapace fully formed) of the cylidroleberid Postasterope barnesi (F) and E. carcharodonta (G). Ommatidia are forming in the cylindroleberid embryo (arrows) but are absent in E. carcharodonta. (H, I) Ommatidial structure of E. morini. The schematic is based on panel (H), DAPI nuclear staining, and previous data on ostracod eyes (Land and Nilsson 1990). The distal portion of the ommatidia is the two lenses, which are clear and highly autofluorescent. These overlie two pigment cells (P) and the crystalline cone cells (C). Three retinular cells (R) were clearly visible, but six to eight have been reported in previous literature (Huvard 1990; Land and Nilsson 1990). A singe cone cell nucleus (C) was visible; the other may have been lost during preparation. Scale bar: (A, B) 500 μm, (C, D, F) 40 μm, (F) 55 μm (G, H, I) 15 μm. DAPI, 4',6-diamidino-2-phenylindole.

The surprising presence of eyes in male, but not female E. morini raises a number of questions. The first is, “Why?” In natural history, “why” questions are evolutionary questions. Why has a particular feature evolved to its present form? Evolutionary hypotheses are often inspired by adaptive explanations – what benefit does a particular trait bestow upon the individuals that posses it? Based on adaptive reasoning, and our knowledge of the natural history, we are currently testing two hypotheses to explain why E. morini males have eyes, but females do not.

The first idea is that males might be using their eyes to find mates. In nature, when females and males differ significantly, the reason often boils down to mating, to the process called sexual selection. Sexual selection occurs when sex-specific traits, like peacock feathers or larger body size, increase the chance of mating. If the trait is heritable, increased mating success will cause the trait to become more common. Peacocks with longer tail features are more attractive and may mate more often, having sons with longer tail feathers. In E. morini, males having eyes might allow them to find more mates.

A second explanation for differences between male and female E. morini is that differing life histories impose different demands on their visual systems. Specifically, we hypothesize that males encounter higher exposure to predators than females. In the E. morini and its closest ostracod relatives (the myodocopids), mating occurs in the water column. Even though most ostracods spend most of their lives in the sediment at the bottom, many swim toward the surface in search of romantic encounters, not unlike the nuptial flights of social insects like ants and bees, where virgin queens take flight to mate. It is at this time, during mating, that E. morini might be especially susceptible to predation, for example by fishes seeking a tasty crustacean morsel. Since females seem to mate only once, and males seem to enter the water column night after night to look for a mate, the males have a higher chance of becoming a meal. Perhaps their eyes allow them to avoid this fate. This predation risk hypothesis is based on piecing together information about myodocopid life history – how then do we know when these tiny animals mate, and how often they mate?

Although we currently know very little about the life history of Euphilomedes morini, we are making informed guesses based on related ostracod species. We perhaps know the most about a different family, the Cypridinidae, studied by James Morin (the namesake of E. morini) and Anne Cohen. Most cypridinid ostracods live in the warm waters of the Caribbean Sea. Since the animals produce a bright blue light (bioluminescence) that is visible by humans, and since the ostracods use this light as a pre-mating display, humans can study aspects of behaviors that could not be studied in E. morini, which does not produce light. Not unlike fireflies that are conspicuous on midsummer’s nights in the eastern and central US, the Caribbean cypridinids (‘sea fireflies’) produce coded messages by flashing. Male sea fireflies swim into the water column shortly after sunset and begin flashing their bioluminescent signal in hopes of attracting a female. Some males, called ‘sneakers’, follow the more industrious males without producing any light codes themselves. These sneakers hope to mate with an attracted female, without expending the energy to produce the signal. Mating presumably takes place in the water, after which females brood their young inside their shells. In captivity, females stored sperm from one mating event, which was used to fertilize multiple broods, and the females might not mate again after their first nuptial swim.

Fig 3. Small blue circles represent discrete flashes of light produced by male bioluminescent cypridinid ostracods. Patterns of different species are illustrated, with white arrows showing the direction of swimming of an individual animal producing the pattern over time. Each pattern is characteristic of a different species and are performed above different microhabitats. Original figure in black and white line drawing by Jim Morin and Anne Cohen. Color and photos added by T. Oakley.

There is also indirect evidence that Euphilomedes females only mate once and that males seek mates more often. In museum-preserved animals, females with broods are missing their swimming appendages. In many of these females, swimming appendages have been found in their guts. This suggests that after mating, female Euphilomedes consume their own swimming appendages, committing them to a celibate life in the sediment. Such behavior may seem strange by human standards, but it is not without analog in other animals. For example, ants hydrolyze their flight muscles after their nuptial flight, gaining energy from a structure that will no longer be needed. In contrast to females, we think that Euphilomedes males swim in search of females more commonly. In Puerto Rico, we found by sweeping nets through the water that swimming males outnumbered swimming females some 1000:1 at the peak activity time after sunset. Taken together, these data suggest a life history whereby eager males swim very often in search of mates. But females spend much less time swimming, instead mating once or few times before returning to the sediment to brood their young. All these small swimming male ostracods could provide a feast for predators such as small fishes, which are known to consume Euphilomedes.

To test the hypotheses that male E. morini eyes help them find mates and/or help them evade predators, we will make calculations of their optics, and perform behavioral experiments. Estimates of the visual abilities of males can be made by measuring aspects of their eyes, such as the number of facets, and the size of the lenses. If male eyes have enough resolution to see larger predators at a distance, but not enough resolution to see females until they are very, very close; this would support the predator-evasion hypothesis. We will also experimentally inhibit the vision of males. If the experimental animals are poorer at finding mates or evading predators, either hypothesis could be supported. Nature often shows us that there are multiple answers for “why” questions, perhaps even some answers we have not considered here.

For many, the beauty and allure of biology lies in the rich diversity of life. This diversity is apparent when we gaze at a tangled bank, or hike through a rainforest. But this amazing diversity is everywhere. The next time you walk on Stearn’s Wharf or Goleta Pier realize that many amazing creatures are living just meters below your feet. Even the cryptic have lessons to teach us about biodiversity.

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.

Ostra-blog 6 - Ostracodology and the Nobel Prize

Dagummit! I've been scooped again by the guys at the other 95% by this post: The Other 95%: The Nobel Jelly - Aequorea victoria . They point out that one of the winners of this year's Nobel Prize for chemistry is marine biologist, chemist, and one time ostracodologist, Osamu Shimomura. [By the way, I didn't invent the word ostracodologist - we actually use that to describe ourselves].

Early in his career, Shimomura studied bioluminescence in Vargula hilgendorfii (he called it Cypridina hilgendorfii, which is a synonym for Vargula hilgendorfii. Vargula is usually used today, the taxonomy is a bit complicated, and I won't go into it here). After that, Shimomura went to work on the jellyfish Aequorea and its bioluminescence. It turns out that Aequorea produces light with a protein called aequorin, which sends light to another protein (Green Flourescent Protein=GFP) that emits green fluorescence. GFP is today used in all sorts of applications, as Eric at TO95% nicely explained.

There also is one more connection between GFP and ostracodology. An ostracodologist actually named GFP (Morin and Hastings, 1971)! Jim Morin is a prominent ostracodologist, who, with Anne Cohen has described, in often exquisite detail, the biology of bioluminescent ostracods from the Caribbean. In my talks on ostracods, I often use a slide based on their work:

Fig 1. Small blue circles represent discrete flashes of light produced by male bioluminescent cypridinid ostracods. Patterns of different species are illustrated, with white arrows showing the direction of swimming of an individual animal producing the pattern over time. Each pattern is characteristic of a different species and are performed above different microhabitats. Original figure in black and white line drawing by Jim Morin and Anne Cohen. Color and photos added by T. Oakley.

Male ostracods of this family signal to females using flashes of light in rather complex species-specific patterns, often over sterotyped microhabitats. These Caribbean species are related to Vargula hilgendorfii (ostrablog 5), which does not signal. In the Caribbean species, there are even "sneaker males", males that follow a signalling male, without using the energy to signal themselves, in an attempt to mate with females attracted to those signals. I guess in bars, humans call this something like a "wing man".



I think this is a great example of how solid basic research will often lead to great advances. Shimomura was interested in bioluminescence because of pure scientific curiosity. I doubt he was aiming for a Nobel. The general public often does not understand this. In the 1970's, I'm sure some people wondered why anyone would want to spend enormous time and energy studying a glowing protein of a jellyfish. But that scientific curiosity has now paid big dividends!

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.

Ostra-blog 4 - Colymbosathon ecplecticos

Last week, somewhere near the top of my mental list of candidate species for ostra-blogs was Colymbosathon ecplecticos. A couple years ago, this species burst on to the ostracod scene, causing a global media event. Ostracodologists are not used to seeing their favorite animals in the headlines, so Colymbosathon caused quite a sensation. On Friday, Eric at The Other 95% generated a post, Who's Got the Oldest?, with Colymbosathon playing the prominent role. Eric described some of the species' vitals. Yes, it's the oldest fossil with identifiable male parts. Yes, its species name means "amazing swimmer with a large penis". Eric's post prompted me to make Colymbosathon the star of this, ostra-blog #4.

Colymbosathon first exposed itself to me at a scientific conference. I was immediately drawn to its rather prominent.... eyes. We were in Seattle in November of 2003, about a month before the Science paper was to be published, and cause the aforementioned media blitz. So it came as a complete surprise to me when the first picture of this 425 year-old fossil flashed on the screen. I remember a seeing on the screen a photo similar to Figure 1 below.



Figure 1. Colymbosathon ecplecticos, a 425 million year old fossil ostracod. Image copyright Science Magazine.


I study ostracod eyes, and I've dissected many of them. My attention went directly to the compound eyes. One is marked "le" in the figure above for "lateral eye". That's the left eye, the right eye is higher on this figure, just below the "H" in the figure.

This fossil was preserved about 425 million years ago in three dimensions inside a volcanic nodule. The scientists break open such nodules in search of interesting fossils. When they find one, they make an image of the fossil at the point it broke, and then grind away a tiny bit of rock (10 microns or so, if memory serves) and take another picture. Doing this procedure over and over again gives them a stack of images, which they can put together computationally to yield full 3-dimensional reconstructions of the fossils. For ostracods and other small animals, this is completely amazing. For most ostracod fossils, only their carapace is preserved, it's made of calcium carbonate. On a few fairly rare occasions the "soft parts" of ostracods are also preserved. (Soft parts refers to the non-carapace parts, even though they are not all that soft, having a chitinous exoskeleton). But even when soft parts are preserved, there were no cases where the full 3-dimensional structure was visible. With digital reconstructions, movies can be made, and specific parts of the animal can be highlighted or removed in order to view other structures.

Figure 2 - Computer generated image of Colymbosathon (side view). Different parts of the animal are colorized differently to make them easier to see. Faint parallel lines are visible, which is where the original was ground, 10 microns at a time, to yield an image stack of the 3-dimensionally preserved fossil. Image copyright Science Magazine.


It was obvious right away that this was something very special. It clearly impacted my own work on ostracod eye evolution. This marked the oldest ostracod compound eye in the fossil record, pushing back the date some 200 million years. In 2002, I published a molecular phylogeny of ostracods that shows that ostracods with lateral compound eyes are nested phylogenetically within multiple groups that lack lateral eyes. One possible interpretation of this is that lateral eyes evolved within Ostracoda (of course eyes don't evolve from nothing, so if this idea is true, many of the genes used in all animal eyes should still be present in the ostracod lateral eyes). Colymbosathon doesn't itself change these conclusions because it is a member of the same group (myodocopids) that today have lateral eyes. Nevertheless, the Colymbosathon fossil pushes back the origin of ostracod compound eyes quite a bit.

Of course not many other people cared about the eyes. They had other things on their mind. In particular, many journalists really rose to the occasion, devising many very entertaining headlines. Some of my favorites are below, and I've taken the liberty to put them into a few categories.

1. The "size matters" category

l

• Scientists Discover Ancient Gargantuan Penis
• Sea creature impressive in its maleness
• Well-endowed sea creature is nearly half a billion years old
• He's 425 million years old and clearly virile
• Male fossil makes a big impression

2. The "age before beauty" category

• Ancient penis brings fame to lowly fossil
• Oldest male fossil bares all
• World's oldest genitals found in Scotland

3. Wonderful alliteration category

• Phallic fossil found

4. And last but not least, the winkle category, a clipping of which hangs in the lab

• Fossilised shrimp has the oldest winkle in the world

Ostra-blog 3 – How we discovered chupacabra

I’m having a lot of fun with these ostra-blogs, which I started on a whim to increase awareness of my study taxon, Ostracoda (here are links to the first two posts: 1, 2). There are so many ostracods and related stories I want to share, that I hardly know where to begin. I’ve also decided to restrict myself to one ostra-blog per week, so as not to interfere with my ever-so-important other activities, like reviewing papers and sitting in on meetings. Therefore, if there are roughly 30000 ostracod species (fossil plus living), I will finish telling you about all of them by about my 600^th birthday, unless of course new species are described by then. In any event, I have reached a decision on this week’s ostra-blog. Since new species have been the subject of some recent blogs, and since I just saw chupacabra on the internet news, today, I will tell you the story of how my lab discovered and described the ostracod species Euphilomedes chupacabra. (Here is a link to the paper).

On new species

First of all, a word or two about new species: As relayed by The Other 95%, there is little academic reward for describing a species this day in age. Today, scientists are judged by their citation rate, and to a lesser but often still significant extent, by the number of grant dollars they pull in. True, in some cases describing a new species - for example by naming it after, say, Neil Young or Steven Colbert - can bring media attention. But media attention does not translate to grant dollars, and probably doesn’t usually increase citation rate.

Still, there are a few intangible perks to describing a new species. One is a certain understandability that the general public has about new species. If I tell a new acquaintance at a cocktail party (which I attend at least 8 days a week… anyway you know the figure of speech) that “we discovered a new species”, he or she seems to think it is significant. In contrast, if I say, we found a new class of vision genes in jellyfish, their eyes glaze over. Or in response, they might ask something like, “oh wow, so will that help us cure blindness, or better yet vision cancer?”). Another perk is a certain “geek cred” among those who value natural history. After all, you must be a real expert to be able to find a new species right? As I’ll discuss later, a final perk is that you get to name it!

Despite these few advantages, finding new species of ostracods for us is a bit of a hassle, honestly. It means that we really should describe the species before analyzing it (but see above regarding citation rate and grant funds – also I don’t think geek cred increases linearly with the number of species described, I think it asymptotes at about 1.1). This “hassle” of finding new ostracods is a common occurrence. In many places, roughly half of the ostracods I’ve collected are unknown to science. These are not inaccessible places. These places are beaches in the Florida Keys, where tens of tourists snorkel every day, or piers in Japan where people fish, all the time. The coral patch reefs of Australia and Belize sound exotic, and they are fantastically beautiful, but I can get there from here in a day or so in air conditioned comfort while listening to science podcasts. My best case in point for how understudied ostracods are brings me (finally!) to the story of E. chupacabra. I found this species by dipping a bucket in the water on the pier of a marine lab!

The initial discovery

A few years ago, I was visiting the University of Puerto Rico-Mayaguez marine lab, which is in Magueyes, near the famous bioluminescence bay. I was visiting my friend, who is a professor there, and we were using their ship to collect some deep sea ostracods. Before that cruise, I decided to do a bit of collecting near the pier. The marine lab is on a tiny little island. It used to be a zoo, and there are large lizards all over the island, which I’m told are descended from those that escaped from the zoo. To get to the island, one must take a boat across a small channel; they have attendants there 24 hours a day!

I’d collected in the Caribbean before, and I expected to be able to collect Skogsbergia lerneri, a species I’ve collected in Florida and Belize (and a species sure to be on a future ostra-blog). Skogsbergia come to baited traps, so I deployed a trap off the pier of the marine lab. While waiting for the animals to come to the trap, I dipped my bucket in the water. To my great surprise, I saw an ostracod buzzing around in the water like Michael Phelps on steroids. Ostracods are quite small, but they have a pretty distinctive swimming behavior (myodocopids at least). Unlike other things of their size, like copepods, ostracods swim very smoothly. I sucked it up into a pipette, and brought it back into the lab. I couldn’t believe my eyes, I suspected immediately I had a Euphilomedes!!

I was so surprised for two reasons. First, Euphilomedes is one of my favorite genera (another certain ostra-blog candidate), because the males have large compound eyes and the females do not. My lab is interested in how this strange eye dimorphism occurs developmentally and genetically. Second, Euphilomedes had never been described from the Caribbean before, so I knew I almost certainly had a new species on my hands. It turns out that it was a species unknown to science, and I had discovered it literally by dipping my bucket in the water in a place where hundreds of marine biologists, and even ostracodologists had passed; a marine lab of a major university. Still, it would be a few years before we mounted the expedition to find more individuals of this new animal, and before we’d decide on its name.

Study and description

Fast forward a couple of years. I decided it would be a good idea to describe this species I had found back at Isla Magueyes. First, we had started studying eye development of Euphilomedes from California. California water is cold, and the animals do not develop very quickly. I suspect that the new species from the warm waters of Puerto Rico might develop faster, and therefore be better suited as a lab animal. Second, I thought it would be fun to go back to Puerto Rico, and to take a couple students along to help me find out more about this species. The National Science Foundation kindly provided money for an REU (research experience for undergraduates) supplement, which would cover travel expenses for two students go to PR for a month. In addition, they would spend some time in the lab back in Santa Barbara beginning to describe the species. I think it is great to get students out doing field work, where they can gain a real appreciation for the wonder of the natural world. Our first order of business was to find more of this animal.

Why was this Euphilomedes in my bucket when I had just dipped it into the ocean? Well, ostracods usually live down in the sediment, making a living between the sand grains. But some swim, often just after sunset, usually to mate. Some ostracods are bioluminescent, the males signal with flashing lights to attract females (yet another future ostra-blog). I’ve collected some animals (mostly males) in light traps. So, I hypothesized that this Euphilomedes was being attracted to the lights at the pier. The undergrads’ first experiment was to test this hypothesis. To do this, they passed a small net through the water, the length of the pier. They put the resulting critters into a dish and counted what they had, repeating this every 15 minutes. They found that this Eupilomedes had a strong peak of activity about 2 hours after sunset. Essentially all of the Eupilomedes they collected were males, consistent with the idea that males swam around trying to find females to mate with. Females probably only mate once, and then do not swim up any more, thus the strong bias in males versus females.

The students also made many SCUBA dives to find where else this Eupilomedes lives. Another way to collect ostracods is by dragging a net across the bottom of the ocean, where the animals usually spend most of their time. We then sort the sand to keep the size class that will have ostracods, and laboriously sort sand grain from ostracod. This is another reason why it was so great to find this Eupilomedes – it is fairly rare to be able to get so many animals just by dragging a net through the water – we could get hundreds of males at a time this way, without having to sort them from sand. In the end, the students found that this Eupilomedes was living all over around the nearby patch reefs, some times very abundantly, especially in fine grained sand. Hundreds of boats, fishermen, wind surfers and SCUBA divers pass through these waters, all the time; while this unknown and fascinating species lurked inconspicuously between the sand grains below them.

Deciding on a name

A really fun part about describing a species is naming it. I took this pretty seriously, especially given some of the great names that people have come up with. Some of my favorite ostracods (again future ostra-blog candidates) are Harleya davidsoni, coined by my colleagues and motorcycle aficionados Kerry Swanson and Thomas Jellinick, and Kornickeria marleyi, named after Bob by Anne Cohen and Jim Morin. Some scientific names are pretty hard to top, like the clam formerly known as Abra cadabra or the wasp named Pison eyvae. (If you like these, you'll have fun if you check curioustaxonomy.net ). I won't go into some of the other candidate names, just suffice to say that in the end, we decided to name our new species after a mythical creature, "el chupacabra". On our first trip, I had fun joking around about the chupacabra with one of my friends who came along. Also, since the myth started in Puerto Rico, it seemed fitting to name this species after it. We simply dubbed it Euphilomedes chupacabra.

If you don’t know chupacabra already, the myth surfaced in the mid-90’s or so, when livestock, especially goats, began being found dead and ensanguinated, with puncture marks on their necks. The legend of el chupacabra (the goatsucker) has since migrated to other, especially Latin American countries. I just saw a headline today, suggesting people have captured video footage of the elusive chupacabra. Looks like a dog with a big nose to me.

So that is the story of Euphilomedes chupacabra. Perhaps one day, you too can discover a new species by dipping a bucket in the water. They are everywhere, and just think of the fun you can have at your next cocktail party. Oh, and by the way, Euphilomedes chupacabra does not suck the blood of goats, unlike the beetle Agra sasquatch, which really does have big feet. I’m not sure about its sister species, Agra yeti.

Ostra-blog 2 - To e or not to e

I was happy to see that Eric at The Other 95% put up a post about Ostracoda. There, he mentioned some of the stats on the group – thousands of species, both extant and extinct, making a living in pretty much any way you can imagine (except I don’t think there are any true parasites), and living pretty much anywhere there is water. I once hiked to the top of a Santa Barbara foothill (a mountain to a Wisconsinite) and found a crevice in a boulder that had filled with water. It teemed with Ostracoda. They not only live in mountain boulders, but also deep seas, hot springs, and even pools of water that collect in bromeliads.

Eric also raised one of the central issues of ostracodology, a war that has been waged for decades, a debate that elicits passionate arguments from both sides of a fundamental divide. This fray is so contentious as to be officially banned from the Ostracoda email list (called OSTRACON). The moderator, Rosalie Maddocks wrote “We further urge that the debate not be reopened on OSTRACON. We are as unlikely to settle the issue as we are to unite all religions and stamp out all disease.”

What is this debate that so enflames the passions even the most mild-mannered scientists? To e (ostracode) or not to e (ostracod), that is the question. In other words, how to spell the common name of Ostracoda in English?

Perhaps the definitive source on the matter was published in 1981 by Dick Benson, in an article entitled “The odds on "ode" in ostracode, or the omicron and omega of chancy spelling.” Here is a link for those who can access JSTOR.

Professor Benson takes us on a wild ride through history, taking a few pit stops to enlighten us about etymology and the Greek language. He makes a fairly compelling argument that “ostracode” is more linguistically “correct” (can you guess which side of the debate he falls on?). But he is also quick to admit that “because language is based on more than logical correctness, the alternative usage is not considered wrong.”

I will not try to recount this harrowing journey through history and language in any detail. Instead, will leave you with Dr. Benson’s lyrical summary, before divulging which side of the divide I fall on:

In celebration of Oxford’s mode,
Most Americans spell it “ostracode”

The Britisher’s closer proximity to God
Causes him [or her] to spell it “ostracod”.

A German claimed Aristotle said it first,
And of the two “ostracod” is wurst;

While a Frenchman after having learned to spell it,
Said it right, by right appellate.

The Italians with gestures free,
Pronounce one “ostracod-eh” and two “ostracod-ee”

All the rest look on amused,
Most don’t care which one is used.

For now, both “ostracod” and “ostracode” survive;
The two of them very much alive.

I end this ode with a short delighter;
Both may be right, but one is righter!

(Note, Professor Benson signed his poetic summary “Anonymous”, because he “holds popular acclaim to be superfluous”)

Where, you are no doubt wondering, do I stand in this great divide? Well, I usually preach pluralism, but on this I must take a monistic stand. Although typically Americans have used “ostracode”, I favor “ostracod”, which is more typically British (despite this trend, documented by Benson, who combed journals to tabulate preferences, he also points out in an ironic reversal that the British Oxford dictionary favors “ostracode”, whereas the American Webster’s favors “ostracod”!) .

My own reasons for "ostracod" are two-fold. First, this is the word I first learned, from my advisor (typo excepted) and from a paper by Andrew Parker. Have you ever had an old friend, say "Jimmy", change his name to the more adult "James"? You still call him "Jimmy", don't you??

Second, I am a bleeding heart, linguistic liberal. Language is an evolving entity, constraining it by arbitrary rules is kinda a diss, ain’t so? Let’s let language continue to evolve! Language is decided by the masses – it’s what people use that determines its path. The only constraint should be clear communication, not ancient Greek grammar. But OMG - WTF is up with all those textisms? Even a lingustic liberal cannot keep up. ITCCTY (Is this clear communication to you?)

Chat lingo aside, I am not fully anachronistic. Eric at The Other 95% has weighed in on this issue using stunning, awe-inspiring new technology, perhaps not even conceivable in 1981 when Dr. Benson considered the question. Eric set up a GoogleBATTLE, pitting ode versus od. GoogleBATTLES scour the entire World Wide Web, tallying occurrences of one word versus another. Current usage (on the web at least) puts ‘od over twice as well used as ‘ode! Who is righter now?

So to summarize my views:

Although typical Americans might find it odd,
For me to use the Brit word, “ostracod”,
How else could I retain my nickname; “ostra-Todd”?

Ostra-blog 1 - Gigantocypris

I study ostracods, or ostracodes, depending on your preference. Not octapods, as my father-in-law might tell you, but ostracods: Crustaceans of the class Ostracoda. Why you might ask? Well, the origin story is told at the beginning of this post.

Still, you may be asking, WHAT is an ostracod anyway? Many people, even biologists have never heard of an ostracod. This is why I carry a picture of an ostracods in my wallet, sandwiched between my credit cards and photos of my kids. Well, to promote ostracods to the seven readers of this blog, I've decided I would like to start a series of posts introducing ostracods and their amazing biology. I shall dub this series my "ostra-blogs". To kick things off, I'd like to tell you a little bit about Gigantocypris.

Gigantocypris is a deep-sea ostracod, living at around 1000m depth as plankton. Most ostracods are pretty small around half to 2 mm - barely visible to pepper corn sized. Gigantocypris, true to their name are ostracod giants, up to 3 cm in width - ping pong ball-sized. They are caught from big research ships in plankton nets. I've never had the pleasure of collecting one myself, but a colleague very kindly sent one to me by FedEx, so I could see one alive. In life, where people live at least, they are orange-red in color. But in their native deep sea habitat, long wavelength light does not penetrate the ocean very far, so their orange pigment would not reflect any light. Another kind colleague sent me some preserved specimens in ethanol from a ship that sailed the Pacific off South America. The alcohol preservative bleaches pigments and the ostracods turn a ghostly, semi-opaque white. When I grab the test tube, I always think of cocktail onions floating the the liquid - Gigantocypris martini anyone?


Perhaps the most amazing feature of Gigantocypris is their eyes. In most animals' eyes, light is bent and focused with lenses. But a select few bend light with mirrors. Gigantocypris is one of the few, bearing a huge pair of parabolic reflectors behind light sensitive patches. The naturalist Alistair Hardy described the animals this this way in 1959:

The paired eyes have huge metallic-looking reflectors
behind them, making them appear like the headlamps of
a large car; they look out through glass-like windows in
the otherwise orange carapace and no doubt these concave
mirrors behind serve instead of a lens in front.

Mike Land worked out the optics of these incredible eyes. Gigantocypris doesn't focus light beams on to a single point. Instead, a line of focus is made along an elongated retina. These animals probably are maximizing the detection of light out to their sides. There is essentially no sunlight at the depths where we find Gigantocypris, so Land suggests that Gigantocypris is detecting light created by bioluminescent animals. Gigantocypris is, in fact, a predator. Small fishes have even been found in their guts, great fun for an ostracodologist like me, used to painstakingly sorting sand grains from ostracods!

Gigantocypris is probably the most famous of ostracods (with the possible exception of Umihotaru, which will be the subject of another ostra-blog, I'm sure). Gigantocypris having made it to MBARI's deep sea poster (mid-right, #26) and if you watch Blue Planet carefully, you can catch a video glimpse.

I will leave you with some fantastic photos of this beautiful animal that are available on the web.




Charismatic aren't they? (Picture from this polar scientist''s blog)

The picture below is a side view. This one is "pregnant".

Other images are also online. Try this search.