Identifying Shells from Scotland, Spain and Massachusetts

I’ve always loved walking along the beach collecting shells, and just for the thrill of it I decided to identify these shells from three different beaches I’ve visited recently. I was struck by the differences and just wondered what the animals these shells came from looked like. The top row is from Portobello beach in Edinburgh, Scotland, the second row is from Sitges, Spain, and the bottom row is from Cape Cod, Massachusetts.

Most of them appear to be bivalves, which are sedentary animals that extend their siphons up to the surface of the sand for feeding and respiration during high tide, and then when the tide goes out they use their muscular “foot” to burrow into the sand in the intertidal zone. By hiding in the sand on shore they are protected from predators and dessication. So when you’re walking on a beach there are likely millions of these guys living below your feet!

Another strategy that some bivalves use (such as mussels and the common limpet) is to cement themselves to a hard surface or another shell permanently. These bivalves are more exposed to animals like lightning whelks, who drill through their shell, extend their proboscus and suck out their prey!

The top row from Edinburgh turned out to be Patella vulgata, or the “common limpet”, a common edible european sea snail. Apparently they grow on rocks and you can pry them off with a knife, and are supposedly delicious with butter and black pepper.

     

I believe the three shells in the very middle of the photo (from Spain) are Cerastoderma edule or the “common cockle”, which is found commonly on European beaches. These are the ones that burrow down into the sand below your feet. This species is also eaten widely and even farmed commercially in the UK.

Back in the neolithic age (6000 B.C.) primitive humans used these shells to create pottery decorations, the raised lines of the shell causing imprints on the clay. This type of pottery is known as “Cardial” because the old latin name for  Cerastoderma edule was Cardium edulis.

The three shells in the bottom left of the photo (from Cape Cod) appear to be in the family Pectinidae, which are also known as scallops. These guys don’t have a siphon like other bivalves, and actually catch plankton in their mouths. They have 100 bright blue eyes all around the edge of their shells that can distinguish from light and dark, and they can actually swim in short bursts by shooting water through their shells!

I believe the bottom right, spiraled shell (another from Cape Cod) is a Lightning Whelk (Busycon perversum) which is by far the coolest name. These are the predator sea snails mentioned earlier that extend their proboscis into the bivalves and suck them out like soup! The lightning whelk is so named because it’s the fastest draw’ in the west. Their sinistral (left) spiral was thought to be sacred by the Native Americans and it’s pretty unique to North America.

Here’s a video that shows you how big these snails can get, usually up to a foot long!

Lasers

Sometimes you hear something that completely blows your mind, along with all your pre-concieved notions and knowledge garnered from years of government loan-funded education. You’re going about your day, you ask someone a question, and you learn something that changes your perception forever. Ok so maybe it’s not as dramatic as all that, but you can decide.

In basic biology you learn about cells, powered by mitochondria, which are little organelles inside every single living (eukaryotic) cell that produce the majority of energy required for life. You may have heard about these mitochondria being remnants of bacteria, “swallowed” by another cell billions of years ago. This theory is supported by the fact that every mitochondria has it’s own set of circular chromosomes, separate from the DNA of your cells.

An interesting side note is that these circular genomes can be traced back to every single human’s original ancestor in Africa, a lineage that only follows that of our mothers because mitochondria are only passed from mother to offspring via the egg.

Anyways, these mitochondria, these little remnants of bacteria had another surprise waiting for me that sparked this ‘revelation’ so described earlier. I was shadowing at a veterinary practice in Fort Collins, Colorado when the vet I was working with pulled out a ‘therapeutic laser’. These lasers come in different wavelengths in the infrared range, depending on the depth and use.

    

I had used these lasers before, but I realized that I didn’t know how they work. I asked the vet and she said that the infra-red light of the laser stimulates the mitochondrial cytochrome C oxidase, which is an important protein involved in energy production in the mitochondria. (It’s the last complex in the electron transport chain). When you stimulate the cells with the right wavelength, you cause the production of excess energy, causing the cells to divide faster and to heal more quickly.

This means that every animal, every human is part plant! (sort of) That means that we can actually convert some forms of light to energy! So cool. If you think about it, stimulating very closely related chromophores such as rhodopsin (in your eyes) and chlorophyll (in plants) causes downstream reactions that cause, respectively, the sensation of sight and energy production from sunlight.*

I thought this was amazing because you’re taught in biology that animals convert glucose, water and oxygen to energy, and that plants do it via chlorophyll. But the reality is actually a bit blurred. Our mitochondria are acting like little plants!

Before you go baking your wounds in the midday sun though, you have to remember that sunlight also contains many harmful wavelengths, specifically UVA and UVB, that destroy your cells and cause mutations. These therapeutic lasers are tuned to a specific infra-red frequency, which is just on the edge and beyond the range of visible light.

Cool right?

Biology nerds please read on…

Another proposed/additional mechanism for the laser’s healing effects on cells is the production of reactive oxygen species, which can cause cell cycle stimulation via activating intermediates like NFkB (Chen et al. 2011). NFkB is a transcription factor that regulates inflammatory and stress-induced survival responses.

*Something cool from a chemistry point of view is the similarity between the chorophyll molecule, cytochrome C and hemoglobin. Hemoglobin has the heme group, with is a cyclic ring of carbon with iron in the center. In chlorophyll a very similar cyclic ring encircles a magnesium atom instead, and Cytochrome C contains two heme groups and two copper complexes. I’ll leave a chemistry major to take it any further ☺

Karu, Tiina (1999). Primary and secondary mechanisms of action of visible to near-IR radiation on cells. J. Photochem. Photobiol. B. 49, 1–17.

Karu, TI et al. (2008). Absorption Measurements of Cell Monolayers Relevant to Mechanisms of Laser Phototherapy: Reduction or Oxidation of Cytochrome c Oxidase Under Laser Radiation at 632.8 nm. Photomedicine and Laser Surgery 26, vol 6, 593–599.

Chen, A.C. et al. (2011) Low-Level Laser Therapy Activates NF-kB via Generation of Reactive Oxygen Species in Mouse Embryonic Fibroblasts. PLoS One. 6(7), e22453- e22453.