Friday, October 25, 2013

Everyone loves a pretty seashell right? I know I do. Although their aesthetic qualities have intrigued Florida locals and tourists alike, they're also extremely important resources for archaeologists studying prehistoric coastal and inland waterway occupations.

Beautiful right?

This blend of malacology (the study of mollusks, which also includes animals like squids and octopuses) or conchology (often associated with the amateur collecting of shells) with archaeology has been deemed "archaeomalacology" by scholars both in the United States and in Europe and is considered a sub-specialty of zooarchaeology--the study of animals at archaeological sites. Here in the Southeastern United States, notable scholars include Karen Walker, Douglas Jones, and Irvy Quitmyer (Florida Museum of Natural History), Cheryl Claassen (Appalachian State University), Gregory Waselkov (University of South Alabama), Betsy Reitz (University of Georgia), and Fred Andrus (University of Alabama) and others!

Of course, these researchers do study shell midden deposition and site formation processes similar to archaeologists working in other settings around the globe, but they also consider the biology and ecology of the organism to understand:

Habitat- what kind of environment does the animal prefer? Subtidal or Intertidal? Marine, Estuarine, or Freshwater?

Archaeological Implications: How far did Natives have to travel to capture this resource? Did they have to swim out into the water or just collect on the beach? Where were they finding these species now deposited in a midden? How has the environment changed/not changed since the time these ecofacts were tossed away?

Locomotion and Activity Patterns- How does this animal move about- can it move at all? Is this species diurnal, nocturnal, crepuscular?

Those oysters aren't walking away.
Archaeological Implications: Could these animals be collected year-round or only seasonally, that is, are they available year-round? Do they have any techniques to resist predation by humans? (for example, lightning whelks can bury into the sandy seafloor)

Diet and Predation- Is this animal an herbivore or carnivore? Does it have natural predators?
Horse conch is the state shell of Florida, and they're always hungry!

 Archaeological Implications: Mobile whelks and conchs will avoid particular regions for extended periods of time (sometimes for several months!) because they know when their predators are most likely to be hunting! In turn, this affects their availability to Native populations.

Reproduction and Ontogeny- How many babies do they have? How often to they reproduce, and generally, how many survive? How long until they're sexually mature? How fast does the snail grow, and when does it grow? How long does it live?

Whelk egg casing

Archaeological Implications: Are these critters sustainable? Could Natives collect them at will because there were too many to deplete a population, OR did they have to manage the resource to ensure lucrative harvests in perpetuity?

As we can quickly see, shellfish ecology is of great use to the archaeologist of coastal Florida! Stay tuned for the next blog in this series, where we will meet--and learn about--several of Northeast Florida's shell residents!

Text and Images: Ryan Harke, FPAN Staff. Full credit to Florida International University (FIU) Department of Marine Biology and Oceanography for the zonation image. Credit to Mike Theiss for the queen conch photo, River Mud for the oyster bed photo, and credit to Karen Checca for the egg casing photo. Full credit to National Geographic and YouTube for the horse conch video.

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