dinoflagellates

Bad “Bugs,” Good Designs — The Case of Dinoflagellates

The other day, we described the exquisite design in the mosquito wing, well aware that mosquitos cause massive pain and death for humanity. We ventured some possible answers to the problem of “natural evil” but quickly retreated to the domain of intelligent design, which cannot venture to answer those questions. ID can, with high reliability however, determine that mosquito flight is exceptionally well designed.

Today here’s a different “bug” (actually, a eukaryotic microbe) that appears well designed to fire amazing weapons at its enemies.

 

Dinoflagellates: The Gatling Gun in the Red Tide

While evolutionists are arguing about which animal came first at the Cambrian explosion (see Nature), worried that the new contender (the comb jelly) is more complex than the old contender (the sponge), they have another problem on their hands. The first biological harpoons to evolve are more complex than the later ones. Evolution always proceeds from simple to complex, you see, except when it doesn’t.

If any organism should qualify for an alien from outer space, the dinoflagellates should be on the list. As the name implies, these complex microbes have “whirling whips” and look like craft from outer space. Second only to diatoms in abundance within marine plankton, some of the 1,555 known species are bioluminescent, creating eerie glowing waves and sparkling sands when they multiply along coastlines. Some are photosynthetic. Readers may recall the species with a camera eye we reported in 2015. And some dinoflagellates can rapidly “bloom” into enormous numbers, creating the “red tide” effect that often proves toxic to fish. Most amazing, though, is their weaponry. They possess hair-trigger harpoons that are beyond belief.

You know to keep away from jellyfish; they sting! Their weapons are “nematocysts” on their tentacles that inject toxins into approaching threats. Some creatures, particularly sea slugs, have mastered the art of stealing these weapons and transporting them unexploded onto their backs. Figure out how that must have evolved! The nematocysts of jellyfish (cnidarians) are pretty sophisticated, but wait till you see what was just learned about dinoflagellate nematocysts, also called extrusomes. Writing in the AAAS journal Science Advances, nine biologists call them “a new extreme in organelle complexity.”

Unexpectedly, our data suggest that different types of dinoflagellate nematocysts use two fundamentally different types of ballistic mechanisms: one type relies on a single pressurized capsule for propulsion, whereas the other type launches 11 to 15 projectiles from an arrangement similar to a Gatling gun. [Emphasis added.]

Be glad these things are so tiny, or you wouldn’t want to get within range. Under the microscope, one can see elongated capsules; in fact, the species with the camera eye has its extrusomes clearly visible in a photo in Figure 1 of the open-access paper (take a look).

How do they work? Well, first consider that the microbe has to protect itself from its own guns. It needs to store them safely till use. Most extrusomes look like a spear on a coiled rope inside an urn:

By capturing the first high-resolution videos of nematocyst discharge (movies S2 and S3), as well as the SEM micrographs of nematocysts arrested at different stages of firing (fig. S2), we were able to make functional inferences about the ballistic mechanism of these complex organelles (Fig. 3). First, the coiled tubule must exit the capsule, which (unlike in cnidarians) has no openings (Figs. 2F and 3). Therefore, the role of the stylet is not only to pierce the prey but also to puncture first the capsule from within, thereby liberating the coiled tubule (Fig. 3). The tubule must pass through two concentric rings (in the novel “stylet base”), then through the center of the nozzle. As the tubule exits through this passage, it forces the operculum open and then uncoils. Once fired, the ballistic tubule gradually dissolves (fig. S2, M to Q). Interactions between Polykrikos and prey dinoflagellates reveal that the tubule does not function as the tow filament, as we initially suspected. Rather, the tubule discharges distally — toward the prey — and is perhaps intended to puncture it.

Sounds nasty, but amazing, too. Figure 2, showing the structures at high resolution, is even more dazzling. Figure 3 shows a model of the discharge mechanism, with electron micrographs of the actual nematocysts in different stages of action. Want to see the “Gatling Gun” version? See the photo and description from the University of British Columbia that talks about the “microbial wild west.” A metaphor from Star Trek might be more applicable. Watch the video (above) of the sharpshooter harpooning its prey and reeling it inside. The scientists were impressed at what they witnessed.

Researchers have obtained an unprecedented view of the ‘ballistic’ weaponry of planktonic microbes, including one that can fire projectiles as if wielding a Gatling gun.

“People hadn’t been able to figure out how these dinoflagellates attack their prey because their ballistic mechanisms are so unexpectedly complex.”

“We think of plankton as the tiny alphabet soup of the ocean, floating around passively while larger organisms eat it,” says biologist Gregory Gavelis, who lead the study while a researcher at the University of British Columbia (UBC).

“But some planktonic microbes, like dinoflagellates, are predators and have developed incredible defensive and prey capture mechanisms.”

Anyone doubt that these harpoons look well designed for their purpose? Evolutionists, of course, doubt it, so they need to find some narrative gloss to paint over the apparent design. In fact, their problem was doubled by their discoveries.

These ballistic organelles have been hypothesized to be homologous to similarly complex structures in animals (cnidarians); but we show, using structural, functional, and phylogenomic data, that nematocysts evolved independently in both lineages.

Chalk this up to a spectacular case of “convergent evolution,” they conclude. But that’s not all: the microbial harpoons are more complex than those in jellyfish! Evolution went from complex to simple, they have to conclude.

Moreover, no homology was detected between dinoflagellate extrusome proteins and the known extrusome proteins from other microbial eukaryotes (for example, ciliates and cryptophytes). How then did dinoflagellates evolve these sophisticated ballistic organelles?

The invoke the narrative of the “evolutionary arms race” for this situation, finding ways to get the more complex Gatling Gun from simpler structures. It’s only a narrative, they admit: and a backwards narrative at that.

Although our hypothesis that a cellular arms race drove the elaboration of extrusomes has yet to be tested, it is clear that obligate predation has become a successful strategy for these dinoflagellates [that is, polykrikoids have lost photosynthesis multiple times]. Despite the misconception that phytoplankton are passive cells, eukaryotic algae have given rise to (and arose from) multiple predatory lineages and, in the process, have independently evolved sophisticated ballistic organelles that exceed those of animals in complexity.

End of story. That’s the last sentence in the ending discussion. It’s like, “We’ll get back to you on that.” Evolutionary explanations seem to be perpetually on back order.

It looks like we can dispense with evolutionary explanations for weaponized microbes for now. But as intelligent design advocates, we are moved to think about the origin of sophisticated mechanisms whose function is to inflict pain and kill. We live in a designed world filled with teeth, toxins, and traps. This reality contributed to Darwin’s doubts about Paley’s beneficent artificer. But if Darwin’s solution cannot work — if design is real rather than apparent — then of necessity we must think along different lines.

Unlike mosquitos, dinoflagellates pose no big hazard to humans (unless one consumes shellfish contaminated by a red tide), so the problem of natural evil differs somewhat in this case. Nevertheless, pain is not restricted to humans, as anyone with a suffering pet knows all too well. Some jellyfish nematocysts are so dangerous, they can kill a man. Why would a designer create things that seem designed for pain? Once again, ID cannot answer that question. However, there are smart people in the fields of ethics, philosophy, and theology who have given it a lot of thought. C. S. Lewis, for one, wrote a book on The Problem of Pain. We could not begin to do it justice in a summary, but our book The Magician’s Twin, edited by Discovery Institute vice president John West, explored some of Lewis’s beliefs about intelligent design, evolution, and the limits of science.

Source: Bad “Bugs,” Good Designs — The Case of Dinoflagellates | Evolution News

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