Episode 216 – Atlantic Bay Scallop: Lord of the Eyes

“…and today we’re talking about a familiar creature with a Lovecraftian feature. But more on that later.”

The sea is full of creatures aberrant to polite society. They swim in the murky depths or live in dark crevasses. But even a familiar sea creature may be alien to you when you really get to know them in their environment. To seafood lovers, the scallop is a known entity. A delicious dish with butter and lemon. But the creature alive and in its shell may bear some features that may astonish you. But it shouldn’t be surprising that the ocean hides the strangest secrets in Life, Death, and Taxonomy. 

Description of the Atlantic Bay Scallop

  • Their shells look like pretty quintessential collectors shells – or if there was a seashell icon on Microsoft Word.
  • They’re half-circles that come to a point on one end like an ornamental fan.
  • They also have two little wings coming off the sides.
  • Their shells have waves radiating outward, making them look like a delicious sun chip
    • It’s usually dark brown at the ridges of the waves and lighter brown in the valleys
  • The clam itself is a series of organs protected by the shell. Its kidneys, intestines, nerves, and gills are all kinda just stuffed into the shell. 
    • They don’t have brains, but they do have nervous systems that allow them to move around, find food, and avoid predation.
  • It also has a large muscle in the center that allows it to open and close its shell.
  • The edges of the clam are lined with tentacles.

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com. We don’t have a new Measure Up intro! 

  1. Albatross
  2. Big Gull
  3. Cormorant
  4. Deadlock


  • 60 to 70 mm (2.7 inches)
  • How many Atlantic Bay Scallops go into the widest canal in the world?
  • Hint: The widest is the Cape Cod canal which separates Cape Cod from the mainland. It was constructed between 1909 and 1916 and it’s about 28 km (17.4 miles) long.
  • 2,400 scallops. 164.6 m (540 foot) wide.


  • 0.01 – 0.02 oz (0.35 – 0.52 g)
  • How many Atlantic Bay Scallops go into the Giga Pearl?
  • Hint: The pearl is the largest non-nacreous pearl known to exist. It’s worth around $60 to $200 million dollars. It was formed by a giant clam and it’s currently on display being held by a golden octopus sculpture. 
  • 53,173 scallops. The pearl is 27.65 kg (60 lb 15oz). 

Fast Facts about the Atlantic Bay Scallop

  • Range: Lives along the cost of the northwest Atlantic from Cape Cod to the Gulf of Mexico
  • Diet: They open their shells to filter algae and other detritus out of the water
  • Behavior: 
    • You don’t usually think of clams as mobile, and most really aren’t
    • But the bay scallop is actually able to swim in quick bursts by opening and closing their shells and spitting water out
    • They can also use their “foot” to help them burrow into the sand on the seafloor
  • They can create pearls, though they aren’t super pretty so no one wants them.

Major Fact: Grant Us Eyes 

If you’re diving and you see the quintessential example of a shell with a pleated design and arced shape, you may be looking at a bay scallop. But most people don’t know that it may also be seeing you. 

Unlike most bivalve molluscs, scallops have eyes. And not just one or two of them. Around the lip of the shell opening, you may see dozens of beady little baby blues peering out of the animals protective casing. 

These eyes aren’t as sophisticated as an owls. But they aren’t mere eyespots. Plus, there’s something about them that is unique in the animal kingdom. 

First, it is strange for a mostly sedentary creature to have any kind of vision at all. Scallops can swim sometimes, but they are considered at least semi-sessile. Many scientists believe that eyes are used in locomotion. If you can’t move, you don’t need to see where you are going. 

But that’s not all that’s weird. Scallops have a mirror in the back of their eye called tapetum, which is common among creatures that need to see in low light, like nocturnal animals. In most nocturnal creatures, the tapetum bounces light back into the lens to maximize the amount of light picked up by photoreceptors. 

But in scallops. The tapeta is angled to focus light, which is usually the job for the lens and cornea. But scallops also have a lens in their eyes. In other words, they have two structures in each eye that function like a lense. What else has two lenses?

Telescopes. Scallop eyes are remarkably similar to the way a telescope works. In a telescope, one lense picks up as much light as possible while the second lense magnifies the subject without losing focus. 

Are scallops staring at galaxies? While a many eyed sea creature staring into the cosmos is very Lovecraftinan, the purpose of these sophisticated eyes in a bivalve is still up for debate. Researcher Daniel Speiser, conducted an experiment where he showed scallops a video of food, which they responded to by opening their shells to feed.

Opening your shell as a mollusk is risky. Your shell is safe but you need to feed. Being able to peak out and assess the area for filter feeding may be helpful. Food particles are small and the ocean is dark. Maybe the double-lense helps them see small objects in dark places like telescopes see distant objects in a dark universe. 

Ending: So squirt around the ocean, keep your clam shut, and stare into the cosmic eldritch evil of the universe with your array of eyes like the bay scallop here in LDT.