Do they find the shells lying around and climb inside them? Do the shells form from sand around their glob bodies over the course of a hundred years?
In: Biology
Scallops are a type of [mollusc](https://en.wikipedia.org/wiki/Mollusca). They are [bivalves](https://en.wikipedia.org/wiki/Bivalvia), which describes the way their shell is in two halves, joined by a hinge. You are probably more familiar with their relatives the [gastropods](https://en.wikipedia.org/wiki/Gastropoda), many of which have a shell which have a coiled shell (like the ones you see on garden snails). Other bivalves you may be familiar with include mussels and clams.
The [shell](https://en.wikipedia.org/wiki/Bivalve_shell) is a part of the animal and they grow it. It’s made calcium carbonate which they extract from the water. While in no way a perfect analogy, you can think of it as us growing nails, but nails so big they encase us completely.
Scallops are “small globs of meat” but so are many invertebrates. They are very simple animals with no brain, just a basic nervous system. Most scallops live for a decade or two. Some species can reach [20 years](https://www.fisheries.noaa.gov/species/atlantic-sea-scallop).
Here’s how mollusks grow their shells from Scientific American. “The exoskeletons of snails and clams, or their shells in common parlance, differ from the endoskeletons of turtles in several ways. Seashells are the exoskeletons of mollusks such as snails, clams, oysters and many others. Such shells have three distinct layers and are composed mostly of calcium carbonate with only a small quantity of protein–no more than 2 percent. These shells, unlike typical animal structures, are not made up of cells. Mantle tissue that is located under and in contact with the shell secretes proteins and mineral extracellularly to form the shell. Think of laying down steel (protein) and pouring concrete (mineral) over it. Thus, seashells grow from the bottom up, or by adding material at the margins. Since their exoskeleton is not shed, molluscan shells must enlarge to accommodate body growth. This pattern of growth results in three distinct shell layers: an outer proteinaceous periosteum (uncalcified), a prismatic layer (calcified) and an inner pearly layer of nacre (calcified).”
The shape of the shell has to do with the fact that scallops are free swimming unlike their oyster relatives. They swim by clapping their shell together. If the shell was not symmetrical the scallop would swim in circles. Not good for getting anywhere.
Also they are more than just muscle blobs. They can even have 200 eyes over their mantle. They are pretty complex.
As mollusks develop in the sea, their mantle tissue absorbs salt and chemicals. They secrete calcium carbonate, which hardens on the outside of their bodies, creating a hard shell.
In addition to what others have said, the scallops you get at a restaurant or whatnot are only a small portion of the actual scallop- specifically the muscle that opens and closes the shell. Whole scallops look like this: https://www.chowhound.com/post/recipe-entire-scallop-898901
Much more structure than just a “small globs of meat”!
Latest Answers