Anything-can-happen Thursday
I love the American comedy The Big Bang Theory. It's about physicists at Caltech, and as you may expect, it's a very nerdy show. One of the main characters, Sheldon, is on the Autism spectrum and is notoriously rigid. In one episode, his friends try to shake up his routine by declaring "Anything-can-happen Thursday" and replacing Sheldon's typical Thursday pizza dinner with Thai food. It does not go over well.
Friends, I'm hope you're not eating pizza, because today is Anything-can-happen Thursday.
I'm working on processing the samples I recovered from the Josephine Marie wreck as part of my shipwreck project this summer. You know - the one where I went diving on shipwrecks in Stellwagen Bank National Marine Sanctuary to see whether they could serve as stepping stones for invasive species. At each wreck, I deployed fouling panels and larval traps and collected samples of the adults that were living there. I recovered the fouling panels and larval traps from two of my sites in August this year, but the weather was never calm enough for me to make it to the third site.
Well, I'm currently processing the larval samples from the Josephine Marie wreck, and I had a very Anything-can-happen-Thursday moment.
As I looked through the larval sample, I kept seeing heart-shaped shells. They were bivalves like clams or mussels, because they had two symmetrical shells attached at an umbo - a very standard morphology. I assumed they must have been a species that lived buried in the sediment because I didn't remember seeing bivalves on the shipwreck. I sorted them without thinking much of it.
But then I noticed something else in the larval sample: a juvenile limpet. It's not uncommon for small juveniles to get washed off of their substratum and into a trap, but what actually caught my eye was the larval shell embedded in the juveniles. When shelled animals like snails, limpets, and clams settle, they grow their new shell as an extension of the old one, so the shell they had as a larva remains. The more I looked at the limpet, the more the larval shell looked heart-shaped, just like the larvae I had seen.
But bivalves don't just transform into limpets. They're two separate things. Bivalves are things like clams, and limpets are more like snails. One does not simply become the other.
I took a closer look at the juvenile "limpet." I turned it over. I zoomed in using the microscope. I adjusted the light. And I started to notice something I hadn't seen before - a thin shell on the underside of the "limpet." It had a small hole in it. This wasn't a limpet at all, I realized, but rather a bivalve with a two very different shells.
I pulled out a reference book from my advisor's collection. Marine invertebrates of southern New England and New York. I flipped through the pages until I reached the bivalves. I scanned for one that had two different shells, one hearty and translucent, the other clear and with a small hole. And there it was. Anomia sp., commonly known as a jingle. They're bivalves that live attached to a surface with their translucent upper shell exposed to the water and their thin lower shell facing the substratum. The small hole in the lower shell allows threads to pass through that anchor them to the substratum.
And then it dawned on me. The jingles in my larval trap were not the only jingles I had captured. Larger juveniles had colonized my fouling panels, but I had incorrectly identified them as the limpet Crepidula sp. Now I know that they are jingles.
Altogether, I had 469 heart-shaped jingle larvae in my sample, and another 21 small juveniles. They were the single most common species. Even though I don't remember seeing them on the wreck, I wasn't focused on looking for small bivalves at the time, so I may have missed them. It's an interesting species to be aware of for future studies - maybe they could be a good model species for some of my scientific questions!
Friends, I'm hope you're not eating pizza, because today is Anything-can-happen Thursday.
 |
| Heart-shaped bivalve larvae, magnified 50x |
Well, I'm currently processing the larval samples from the Josephine Marie wreck, and I had a very Anything-can-happen-Thursday moment.
As I looked through the larval sample, I kept seeing heart-shaped shells. They were bivalves like clams or mussels, because they had two symmetrical shells attached at an umbo - a very standard morphology. I assumed they must have been a species that lived buried in the sediment because I didn't remember seeing bivalves on the shipwreck. I sorted them without thinking much of it.
 |
| Juvenile "limpets" from my trap, magnified 50x |
But bivalves don't just transform into limpets. They're two separate things. Bivalves are things like clams, and limpets are more like snails. One does not simply become the other.
I took a closer look at the juvenile "limpet." I turned it over. I zoomed in using the microscope. I adjusted the light. And I started to notice something I hadn't seen before - a thin shell on the underside of the "limpet." It had a small hole in it. This wasn't a limpet at all, I realized, but rather a bivalve with a two very different shells.
 |
| A larger juvenile jingle from my fouling panels. The larval shell is the small yellow spot on the apex. |
And then it dawned on me. The jingles in my larval trap were not the only jingles I had captured. Larger juveniles had colonized my fouling panels, but I had incorrectly identified them as the limpet Crepidula sp. Now I know that they are jingles.
Altogether, I had 469 heart-shaped jingle larvae in my sample, and another 21 small juveniles. They were the single most common species. Even though I don't remember seeing them on the wreck, I wasn't focused on looking for small bivalves at the time, so I may have missed them. It's an interesting species to be aware of for future studies - maybe they could be a good model species for some of my scientific questions!
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