Fossil Friday #12 – The Black Turban Snail (AKA the Greatest Snail There Ever Was)

I’ve been rather quiet on my blog this past year, in part due to an intense workload down in California, studying for my candidacy exam (I passed, phew), the usual suite of conferences and writing, and of course, life. But I’ve also been doing a lot of thinking and reflection on how to be a better science communicator. This year was an immense year of growth for me both as a scientist, and as a human being. The folks of Bodega Marine Lab were amazing, and I learned so much during my time down there about marine science, the importance of collaboration and peers, and how to advocate for science. I am probably going to do a blog or two about my time in California, but I figured I’d start with something familiar.

Anyone who has ever been tide-pooling along the rocky intertidal of the Pacific coast of Canada or the US has probably come across a little blackish-purple snail, often with an eroded apex that can look either pearly or orange, called the black turban snail. Its scientific name is Tegula funebralis (although this is hotly debated, and it should probably be called Chlorostoma funebrale, but I’m not going to get into that). During a low tide, you can find them by the hundreds, clustered around the bottoms of rocks, or in tide pools, munching on their favourite algae.

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Tegula funebralis – the black turban snail

Marine intertidal ecologists are very familiar with this little snail, and most of us are unusually fond of it. Why? It’s hard to explain, but somehow this non-descript little snail, with its little black foot (body) and curious epipodial tentacles that will explore you as it wobbles across the palm of your hand, is very charismatic. It is unusually long lived for such a small snail (up to 30 years), has been used for countless studies, and is commonly found in teaching labs and touch tanks at aquariums (not as scary as in Finding Dory). Some scientists refer to it as the “most noble snail”, and there has even been an article that lightly suggests that Tegula can explain the logic of the universe. I tend to agree.

BunchOTegula
Collecting Tegula funebralis

Tegula is a large genus, consisting of some 30-odd extant (living) taxa found all around the Pacific, including other species such as the brown turban snail, Tegula brunnea, which looks similar to T. funebralis, or a pretty, light coloured one called the dusky turban snail, Tegula pulligo. You can distinguish T. funebralis primarily by its purplish-black colour, eroded apex that will expose the pearly nacre of the shell, and crenulated ornament along the top margin of the whorl (spiral), although this is not always present. T. brunnea is similar in colour, and is also found in the intertidal (lower), but will be more brown than purple, does not have the eroded apex, and for living snails, will have a bright orange band on its foot that is not present in T. funebralis.


The fossil record of the Tegula genus extends back as far as the Cretaceous, to a creature called Tegula jeanae (Squires and Saul, 2005), which interestingly looks a lot like Tegula funebralis. As many Tegula are found either in the intertidal, or in the shallow subtidal, their fossil record isn’t the best, as these environments usually erode, rather than become buried. However, there is some nice material, particularly of T. funebralis, from the Plio-Pliestocene of southern California. Interestingly, I discovered from curators at the Natural History Museum of LA County Invertebrate Paleontology Collection that while most fossils lose their colour, even from the Late Pliestocene (~12,000 – 126,000 years ago), T. funebralis retains its dark purple colour, making it very easy to spot among the drawers of dusty, beige fossil shells. In addition to fossil material, there is also a lot of archaeological material from shell middens, as Tegula has been used for food by people all along the coast (Erlandson et al. 2015).

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A behemoth Tegula funebralis with 9(!) repair scars

Not only is Tegula a cute little snail and excellent experimental animal, it is also important ecologically. Being one of the most common and abundant intertidal snails, it is food for lots of animals, such as sea stars, crabs, octopus, and even birds. One of the reasons we study it so much in the Leighton Lab is because populations of T. funebralis often have lots of repair scars from crab attacks, meaning we can study how this crab-snail interaction is affected by things like wave-energy, environment, other potential prey, and even ocean acidification (which is what I am exploring for my dissertation). Unfortunately, OA studies have found that T. funebralis is in trouble (e.g. Jellison et al. 2016). From the results of my experiments, it is in huge trouble (Barclay et al. 2017 – stay tuned for updates!). And if something happens to Tegula, it could be detrimental for intertidal ecosystems. Think of it this way: without Tegula, there would be a lot less food for predators, which puts more pressure on other prey animals and could disrupt populations their populations, potentially messing up the “food chain” or established interactions within the whole ecosystem.

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Tegula funebralis about to become a snack for a hungry sea star – credit: Darrin Molinaro

So the next time you happen to visit the Pacific coast, keep your eyes out for the black turban snail. Once you spot one, you’ll notice them all over the place. Lightly twist one off a rock and place it in your palm. If you are gentle and patient, it will venture out of its shell and explore your hand. Remember that they are in trouble due to climate change, and will need our help to make decisions that will work towards protecting them and their environment. And if you see a piece of kelp washed up, try feeding it to them. It’s their favourite snack, and it’s fun to watch their little raspy radula (tongues) hard at work. We could all benefit from taking to time to just sit, soak in their rocky intertidal home, and explore life at a “snail’s pace”.

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Tegula funebralis in their intertidal habitat credit: Steven Lonhart (SIMoN


Literature Cited (and other cool links):

Barclay, K. M., Gaylord, B., Jellison, B.M., Shukla, P., Sanford, E., and Leighton, L.R. 2017. Impact of ocean acidification on shell growth and strength of two intertidal gastropods exposed to the scent of predation. Western Society of Naturalists 98th Annual Meeting

Erlandson, J. M., Ainis, A. F., Braje, T. J., Jew, N. P., McVey, M., Rick, T. C., Vellanoweth, R. L., and Watts, J. 2015. 12,000 Years of Human Predation on Black Turban Snails (Chlorostoma funebralis) on Alta California’s Northern Channel Islands. California Archaeology 7:59-91.

Jellison, B. M., Ninokawa, A. T., Hill, T. M., Sanford, E., and Gaylord, B. 2016. Ocean acidification alters the response of intertidal snails to a key sea star predator. Proceedings of the Royal Society B 283:20160890

Squires, R. L., and Saul, L. R. 2005. New Late Cretaceous (Santonian and Campanian) gastropods from California and Baja California, Mexico. The Nautilus 119:133-148

At A Snail’s Pace – Bay Nature – a great article in which Tegula explains the logic of the universe

WoRMS – World Register of Marine Species – Tegula

Gastropods.com Tegulidae – has great pictures!

 

 

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