Top 5 Scallop Facts

A scallop is a siphon-less bivalve shellfish with a ring of multiple simple eyes around the edge of its mantles. These shellfish are biologically enclosed by two grooved shells connected by a hinge and two valves. One side of the shell formed of calcium carbonate is slightly flatter, while the other is more concave.

These underwater species have blue eyes and peculiar single adductor muscles. The animal has myriad shades, from dull creamy tinges to vivid hues. Their mouth or openings are covered by cilia that allow the passage of food and feces.

Top 5 Astounding Facts About Scallop

Top 5 Astounding Facts About Scallop

Scallops cannot close and seal their shells completely like mussels and oysters. They are intolerant of fresh water and can only survive in the deeper total salinity seawater.

Did you know you can tell the age of a scallop? Each annulus on the ring of a scallop shell represents a year of growth. However, a ring might symbolize a stressful incident in a scallop’s life.

Below are the top five astonishing facts about scallops that you need to know.

  • Scallops’ Eyes Have Photoreceptors

A scallop’s blue eyes have photoreceptors, which can regenerate. The eyes are sensitive and have tiny mirrors that are the primary source of interaction with the environment. These eyes can be up to 200 in number. 

The eyes are embedded at the base of the sensory tentacles that run along the outer edges of their upper and lower shells. They form a luminous blue tinge that allows the scallop to perceive and respond to light, dark, shadow, and motion. One of the most interesting fun facts is how the scallops use their retinas to focus light, a cornea’s job in human eyes.

  • Scallops Are Filter Feeders

Scallops feed by purifying plankton in their surrounding waters. As water enters the scallop, mucus traps planktons in the water. This is followed by tiny hair-like cilia moving the food into the scallop’s mouth. The underwater animal’s diet includes tiny organisms like planktons, krill, algae, and larvae.

  • Scallops Swim by Clapping Their Shells

Scallops are surprisingly speedy free-swimming animals, unlike the sessile mussels and clam bivalves that attach themselves to a substrate. They escape sea star predators and danger by clapping their shells repeatedly using their highly developed adductor muscles.

This action forces a jet of water to pass the shell hinge and propels the scallop forward. The adductor muscle is the round, fleshy yummy seafood that controls the opening and closing of the shell. It varies from white to beige, and any seafood lover will instantly recognize it.

  • Scallops Reproduce Externally

Scallops spawn by releasing eggs and sperm into their water environment. Most scallops are hermaphrodites, meaning they have male and female sex organs.

Scallops spawn in late summer and early autumn. Once the egg is fertilized, the larvae drift in the water column for up to seven-week before sailing to the sea floor. The larvae attach themselves to a substrate with byssal threads, which they let loose as they grow and become free-swimmers.

The veliger creates a shell as it develops into an adult and might stick around or swim away.

  • Scallops Have Fully Developed Nervous System

Scallops lack an actual brain, just like all other bivalves. Instead, their highly developed nervous system is controlled by three paired ganglia found at various points throughout their anatomy. Their nervous system is controlled by cerebral ganglia, the pedal ganglia, and the visceral ganglia.

When a scallop opens and closes its shell, that is a reaction due to its nervous system, and not calling out pain or danger.


Scallops have no brain, only a highly developed nervous system. Unlike the hound fish which use their reflexive bodies for survival mechanisms, the scallop species’ eyes are imperative for their survival and are used as early warning signals to escape predators. Their sex can be distinguished where the female scallop’s reproductive organs are red while the males’ are white.


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