Crustaceans belong to a larger group of arthropods that includes lobsters, crabs, and shrimp. Shellfish is a broader term that encompasses any aquatic animal with a shell or exoskeleton.

TL;DR Crustaceans Vs. Shellfish

Crustaceans are diverse marine animals like lobsters, crabs, and shrimp, with segmented bodies and jointed limbs. They can regenerate lost body parts.

Shellfish are edible aquatic creatures with protective shells, including clams, mussels, and oysters. They filter-feed and have unique reproductive processes.

Crustaceans and shellfish are distinct categories; crustaceans have segmented bodies and legs, while shellfish have shells and soft bodies.

What are crustaceans?

picture of crustaceans

Crustaceans are a diverse group of animals that inhabit both freshwater and marine environments. They are characterized by their jointed limbs, hard exoskeletons, and segmented bodies. With over 67,000 known species, crustaceans encompass a wide range of fascinating creatures.

From the mighty lobsters to tiny shrimp, crustaceans come in all shapes and sizes. These incredible beings play an essential role in marine ecosystems as they serve as both predators and prey.

Some notable examples of crustaceans include crabs, crayfish, barnacles, and krill.

One distinctive feature of crustaceans is their ability to regenerate lost limbs or even entire body parts. This remarkable regenerative power allows them to adapt and survive in various environmental conditions.

What are shellfish?

picture of clams

Shellfish are a type of seafood that have a hard outer shell, making them distinct from other types of marine creatures. They include various species such as crabs, lobsters, shrimp, and clams. Shellfish are found in both saltwater and freshwater environments.

Many types of shellfish have specialized appendages or filters that allow them to extract nutrients from the water they live in. This unique feeding behavior makes shellfish an important part of aquatic ecosystems.

Another interesting aspect of shellfish is their reproductive process. Many species release eggs into the water where they are fertilized by sperm released by males. These fertilized eggs then develop into larvae before eventually settling on the ocean floor or attaching themselves to rocks or other surfaces.

Crustaceans Vs. Shellfish – Key differences

While all crustaceans are considered shellfish, not all shellfish are crustaceans.


Definition: Crustaceans are a diverse group of arthropods that typically have a hard exoskeleton (shell), jointed legs, and two pairs of antennae. They belong to the class Crustacea and are found in various aquatic environments, including freshwater and saltwater habitats.
Examples: Crabs, lobsters, shrimp, crayfish, and krill are examples of crustaceans.
Body Segmentation: Crustaceans exhibit distinct body segmentation, including a cephalothorax (fused head and thorax) and an abdomen. They often have a pronounced carapace, which is the hard shell covering the cephalothorax.
Respiratory Organs: Crustaceans typically have gills for respiration, which are often located in specialized chambers.
Feeding: Crustaceans are diverse in their feeding habits and can be scavengers, filter feeders, herbivores, or predators.


Definition: Shellfish is a broader term that encompasses a variety of aquatic organisms with shells. It includes both mollusks and crustaceans.
Examples: Mollusks such as clams, mussels, oysters, and scallops are considered shellfish. Additionally, crustaceans like crabs, lobsters, and shrimp are also categorized as shellfish.
Shell Types: Shellfish have shells or exoskeletons that provide protection and support. These shells can be made of calcium carbonate (as in mollusks) or chitin (as in crustaceans).
Respiratory Organs: Mollusks usually have gills or lung-like structures, while crustaceans have gills for respiration.
Feeding: Shellfish have various feeding strategies. Mollusks like clams and oysters are filter feeders, while others like snails are grazers. Crustaceans, as mentioned earlier, have diverse feeding habits.

Image Credits

Featured Image By –  Johnny_px from Pixabay

Image 1 By – © Hans Hillewaert

Image 2 By – Kindel Media

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