How cool are worms? Really cool. Worms are freaking neat. Annelids (the phylum including earthworms, leeches and polychaetes) are just flat out odd sometimes, and odd makes for teachable concepts.
They don’t, not exactly.
They don’t have mouths. They don’t have stomachs, intestines or anuses either, and yet, they eat the bones of dead whales, and are called bone eating worms or osedax, which means bone eating in Latin.
They use a branching anchor with rootlike structures, covered in microvilli, to secrete acid, which breaks down the calcium structure, liberating fats, which are absorbed and then digested by bacteria living in the tissues of the worm. And zombie worms aren’t even the most grossly named of these critters. Behold the bone eating snot flower worm!
So they don’t eat, but do break down bone and absorb food from their surroundings.
It sounds a bit like a fungus, actually. And this can be a great chance for you to talk about how what a normal defining characteristic of a kingdom (ingesting food for Animalia, photosynthesis for Plantae) are sometimes abandoned, but the organism never hops to another kingdom. A ghost orchid that doesn’t photosynthesize is still a plant, existing as a parasite on fungi underground, only poking up to flower on rare occasion. Students often want to think of non-photosynthesizing plants as fungi, and might want to do the same with bone eating worms, but they still have all the other features of their kingdoms. The osedax still doesn’t have cell walls or mycorrhizae like a fungus. It still has closer genetic ties to other polychaetes and annelids than to anything else. The ghost orchid still has cellulose cell walls instead of chitin. It may not have chloroplasts, but it still is a plant. Great chance to have a lesson on phylogenetic trees.
Another topic you can bring up is the use it or lose it concept. Osedax don’t use a digestive tract and don’t need one. The genes for a digestive tract are turned off and over the millions of years since they evolved, the genes probably have become mutated into a non-functional state. It was once assumed that once you go down this tract, you can’t go back, but scientists have found that geckos have gained and lost their adhesive toe pads several times, and some lineages of scorpions have gone from surface to cave dwelling and back, and lost their eyesight and regained it. The longer you don’t use something and it remains unexpressed, the harder it is to reactivate, but it isn’t impossible.
I would really love to see a study of the early development of these worms, especially to see if their larval forms have digestive tracts.
One other cool detail… Osedax have both male and female sexes, but the males live in a larva like state inside the female.
Worms = cool
A new gene in the influenza virus has been discovered. Let me pick up my teeth. Influenza just went from a genome of 10-11 genes to 11-12.
The gene is hidden in the code of another gene, and it appears to limit the severity of the immune response. If the mouse model is correct, when this gene works, the flu symptoms are less severe. If it is mutated, the flu is more severe and is more likely to kill otherwise healthy people.
The gene wasn’t discovered until now because it is found after the main gene on segment three starts. It basically is a second open reading frame (this is the link to the original paper in the journal Science), and is activated by a ribosomal frame shift. (Does this sound like it may be for an undergraduate genetics course? Oh yeah. But don’t be afraid of handing it to a gifted high school student.)
Basically, the gene is transcribed as normal, making the viral mRNA. The mRNA is then translated, and when the ribosome reaches the start of the internal gene, it slips, missing a nucleotide and the rest of the protein is produced according to the internal gene. This is similar to eukaryotic alternative splicing, and is a very cool way to get two genes coded into the space of one.
This produces a protein that represses the genes of the cell, and probably inhibits the cell from putting up the little red flags that tell the immune system that it has been infected. Less immune response, less chance for a cytokine storm, the nightmare scenario for flu.
Misc science goodness:
Neutron star racing across space
Graphene may make for an efficient way to make salt water into fresh
Nice way to explain the different parts of the electromagnetic spectrum (xrays to visible light to radio waves) and their significance to astronomy
Why does coal become rare in the fossil record around 300 million years ago? Fungus that could break down lignin evolved about that time.
A rare freshwater mussel is facing extinction.
Animals from the Ediacaran period preserved by volcanic ash.