Tubeworms and the Impact of Evolutionary Theory on Medical Research

This is another from the archives….
Tubeworms or interesting creatures. They live deep in the ocean near volcanic vents where the temperature often exceeds 200 degrees. They have no mouth or stomach, instead they acquire all their nutrients from colonies of symbiotic chemosynthetic bacteria.

More on Bone Eating Sea Worms

As I mentioned in a previous post some sea worms feed on whale bones. BBC News is reporting some have been discovered off the coast of Sweden (they were previously known only off the coast of California).

above is a picture of the Swedish species. Below is a scanning electron micrograph of the sea worm.

Here is another picture:

Here is what is know, so far:

Osedax worms are about 1-2cm in length.

A scanning electron micrograph shows up remarkable detail in the North Sea worm
They root themselves to the whale bones which they then plunder for oils with the help of symbiotic bacteria. The worms’ flower-like plumes pull oxygen from the water.

There is a mystery:

Their reproductive system is extraordinary – certainly in the case of the Pacific Osedax.

“The female Pacific worms keep males inside their tube as a sort of little harem that fertilises eggs as they are released into the water column,” explained Dr Glover.

“We’re not sure what’s happening with the reproductive biology of the Swedish worms yet. We’ve only got females; we haven’t found any males. It’s a bit weird.”

Scientists have established that all of the Osedax species so far identified appear to be closely related to vestimentiferan tubeworms, which are found only at the volcanic cracks in the ocean floor called hydrothermal vents.

There is also a fly in the ointment. Since these worms live on whale falls (I. E. carcasses of dead whales that sink to the ocean floor) it is believed that whale carcasses act as stopping points that allow organisms to move around the ocean floor. If whales have low population numbers or are extinct this “island hopping” can’t work:

What concerns researchers is that the commercial hunting which so devastated whaling populations would also have severely curtailed this activity by reducing the incidence of whale fall.

It may even have led to the extinction of some bottom-dwelling organisms that depended on this rare but concentrated nutrient supply.

Tubeworms and the impact of Evolutionary Theory on Medical Research

Tubeworms or interesting creatures. They live deep in the ocean near volcanic vents where the temperature often exceeds 200 degrees. They have no mouth or stomach, instead they acquire all their nutrients from colonies of symbiotic chemosynthetic bacteria.

Tubeworms 1

The red at the top of the tubeworm is due to hemogloblin. One of the other unique aspects of the tubeworm environment is the extremely large amount of sulfides. Sulfides present two problems to tubeworms. First, free sulfide reacts with oxygen. Second, they have to provide sulfides to the symbiotic bacteria that provide the tubeworms nutrients.

Tubeworm 2 

Tubeworms actually have two different types of hemoglobin. The second type is more interesting. “The hollow spherical structure in the hemoglobin of this species includes 12 zinc ions in depressions at the outer part of the molecule,” explains Flores. “These ions form a reversible bond with the hydrogen sulfide molecules that could block the oxygen-carrying sites, allowing the molecule to simultaneously carry oxygen and sulfide.”
Flores says that the hollow spherical structure is unique. “Human and other hemoglobins have a ‘globular’ form, but none have been discovered with this symmetrical sphere. This sphere is a very stable shape, which may be part of the adaptation for the extreme conditions in which these worms thrive.”

Recent medical studies have focused on the worm’s large hexagonal hemoglobins as possible substitutes for oxygen carriers in human blood. “The newly characterized molecule is substantially smaller than the hexagonal hemoglobin, reducing problems of removal by kidney filtration, but still has six times as many active oxygen-carrying sites as human hemoglobin,” Flores adds.

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So, by studying the evolution of tubeworm:

“Our discovery, which results from a very multi-disciplinary approach, replaces the current paradigm for the evolution of worm hemoglobin by demonstrating that hydrogen-sulfide molecules are bound by a metal ion rather than by an arrangement of amino acids.”

we are led to a possible substitute for oxygen carriers in human blood – which could have many medical applications! Who says evolutionary theory doesn’t have implications for medical research?

For more info go to:
Science Daily , PBS , Exploring the Deep Frontier , Dr C’s Remarkable Ocean World and Here for more info.