Difference Between Clams Mussels and Oysters

The main difference between clams mussels and oysters is that clams live in fresh or salt water, having hard shells that are smooth and shiny, and mussels live in fresh or salt water, having shells that are oval in shape and elongated at the ends whereas oysters live in salt water, having a more calcified, irregular shaped shell.

Clams, mussels, and oysters are three different types of shellfish that are edible. They have one, two or more shells that completely or partially cover their unsegmented body. All three types of mollusks are harvested for food as well as for pearls. That means, all three types of mollusks produce pearls unique to the type of mollusk.

Key Areas Covered

1. What are Clams
     – Definition, Facts, Edible Types
2. What are Mussels
     – Definition, Facts, Edible Types
3. What are Oysters
     – Definition, Facts, Edible Types
4. What are the Similarities Between Clams Mussels and Oysters
     – Outline of Common Features
5. What is the Difference Between Clams Mussels and Oysters
     – Comparison of Key Differences

Key Terms: Bivalves, Clams, Edible Mollusks, Mussels, Oysters 

What are Clams

Clams refer to a marine bivalve mollusk with shells of equal size. They spend most of their lives on the ocean floor partially buried in the sand. The two shells of the clams are connected together by two adductor muscles. Clams have a powerful burrowing foot as well. They always hide away in the sediments. 

Figure 1: Clams

Clams are generally consumed in a dish called clam chowder. Most of the edible clams are oval in shape. However, the razor clams, which are also edible, have an elongated shape. Clams are used as a food in North America, Italy, Japan, and India.

What are Mussels

Mussels refer to any of bivalve mollusks with a brown or purplish-black shell. They live in both freshwater and marine water. Most of the edible, marine mussels belong to the family Mytilidae. The shell of the mussels is asymmetric when compared to the shell of the clams. The outline of the shell is elongated. The shell is less oval or circular in shape as well. The color of the shell can be dark blue, brown or black. The inside is silver or grayish. Freshwater mussels species include freshwater pearl mussels.

Figure 2: Blue Mussels

Mussels live attached to the substrate with the help of their byssal threads in the intertidal zone. Some edible mussel species include blue mussels, California mussels, Mediterranean mussels, Mytilus coruscus, Perna canalicula, Perna perna, Perna viridis, etc. 

What are Oysters

Oysters refer to any of the bivalve mollusks with rough irregular shells that are often eaten raw. They live in marine and brackish habitats. The shell of the oysters is highly calcified and somewhat irregular in shape. The shape of the shell is oblong rather than oval shape. The two shells are connected to each other by a small hinge. Oysters have a special “siphon” in the body, helping to take the water in and filter it. 

Figure 3: Oyster

Oysters mainly live attached to a surface and they are also free to move. Oysters can be eaten raw and some edible oysters include Auckland oyster, dredge oyster, mangrove oyster, Ostrea angasi, Ostrea edulis, Pacific oyster, rock oyster, Sydney rock oyster, and Portuguese oyster. 

Similarities Between Clams Mussels and Oysters

• Clams, mussels, and oysters are edible mollusks.
• They are invertebrates.
• They have one, two or more shells that cover their body.
• They have a soft, unsegmented body.
• They are filter-feeders.
• All types produce pearls.

Difference Between Clams Mussels and Oysters

Definition

Clams: A marine bivalve mollusk with shells of equal size

Mussels: Any bivalve mollusk with a brown or purplish-black shell

Oysters: Any bivalve mollusk with rough irregular shells that are often eaten raw

Family

Clams: Family Veneridae

Mussels: Family Mytilidae

Oysters: Superfamily Ostreidae

Habitat

Clams: Live in fresh and salt water

Mussels: Live in fresh and salt water

Oysters: Live in salt water

Shell

Clams: Hard shells that are smooth and shiny

Mussels: Somewhat smooth shells

Oysters: Rough shells

Shell Shape

Clams: Equal, oval-shaped shells

Mussels: Asymmetric, oval or circular-shaped shells with elongated ends

Oysters: Irregular-shaped shells

Two Shells are Connected by

Clams:  Two adductor muscles

Mussels: Byssal threads

Oysters: A  small hinge

Locomotion

Clams: Have a foot to travel

Mussels: Sessile

Oysters:  Fairly mobile

Cooking Technology

Clams: Steamed or can be eaten raw

Mussels: Exclusively cooked

Oysters: Raw or cooked

Conclusion

Clams are bivalve shellfish that live in either fresh or salt water. They have hard shells that are smooth and shiny. In contrast, mussels live in fresh or salt water, having shells that are oval in shape and elongated at the ends. Moreover, oysters live in salt water and they have a more calcified, irregular shaped shell. All types of shellfish described above are edible and they produce pearls as well.

Reference:

1. “Clam.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 24 Aug. 2016, Available Here
2. “Mytilidae (Sea Mussels).” Naticidae (Moon Shells), Available Here
3. “Oysters.” National Geographic, 12 Mar. 2010, Available Here

Image Courtesy:

1. “Clams” By Marlith – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Blue mussel Mytilus edulis” By Andreas Trepte – Own work (CC BY-SA 2.5) via Commons Wikimedia
3. “559304” (CC0) via pixhere