Is Shrimp Considered a Fish? A Closer Look at How We Classify Seafood

When it comes to seafood, the question of “is shrimp a fish?” is a common one. While shrimp and fish both come from the water, they are quite different creatures and are classified differently by scientists. In this article, we’ll take a closer look at how shrimp and fish compare, how we categorize different types of seafood, and why shrimp is not considered a fish.

The Distinct Differences Between Fish and Shrimp

At a glance fish and shrimp may seem similar since they both live in the water. However, they have several key differences that set them apart

• Skeleton – Fish have internal skeletons made up of bones Shrimp have exoskeletons, meaning their skeletons are on the outside of their bodies like a shell.

• Appearance – Fish come in a variety of shapes, but generally have long, streamlined bodies. Shrimp have short, curved bodies with a distinct bend.

• Limbs – Fish do not have jointed limbs or legs. Shrimp have 10 limbs ending in pincers that they use for swimming and feeding.

• Fins – Fish have fins to help them maneuver through the water Shrimp use paddle-like swimmerets (small appendages) and their tail to propel themselves

• Breathing – Fish have gills to breathe underwater. Shrimp breathe through gills and also have small sacs to help them breathe air at the water’s surface.

These are just a few of the major differences that set fish and shrimp apart biologically. While they occupy the same habitats, their anatomy and physiology are quite distinct.

How We Classify Fish vs. Shrimp

The differences between fish and shrimp are significant enough that scientists categorize them into completely separate groups:

• Fish are vertebrates, meaning they have a backbone and internal skeleton. All fish belong to the phylum Chordata. There are over 34,000 known species of fish.

• Shrimp are invertebrates, meaning they lack a backbone and internal skeleton. Shrimp belong to the phylum Arthropoda, which also includes insects and spiders. There are over 2,000 species of shrimp.

More specifically:

• Fish are classified into the class Osteichthyes, which includes both bony fish and cartilaginous fish like sharks.

• Shrimp belong to the subphylum Crustacea, which includes crabs, lobsters, crayfish, and other organisms with exoskeletons.

Within Crustacea, shrimp belong to the order Decapoda, which are crustaceans with 10 legs.

So while fish and shrimp are both aquatic creatures, taxonomically they belong to completely different branches of the animal family tree.

Other Ways We Categorize Fish vs. Shrimp

In addition to scientific classification, we separate fish and shrimp using other broad categories:

Seafood – This umbrella term refers to any edible animals from the sea. Both fish and shrimp are considered types of seafood.

Shellfish – This refers specifically to aquatic invertebrates with shells or exoskeletons. Shrimp are grouped under shellfish, while fish have internal skeletons.

Finfish – This refers only to fish with fins, to distinguish them from other aquatic life like shrimp. All fish are finfish, but not all finfish are fish.

Scale fish – These are fish covered in distinct scales. Shrimp shells are not the same as fish scales.

So in all of these systems, shrimp are considered shellfish while fish are finfish. Even casual definitions separate the two based on anatomical differences.

Case Study: Are Shrimp More Closely Related to Fish or Lobsters?

To see shrimp classification in action, let’s look at a case study comparing shrimp to fish and another shellfish – lobsters:

• Shrimp and lobsters both have exoskeletons, 10 legs, swimmerets, and live on the seafloor. They are closely related and in the same subphylum (Crustacea).

• Shrimp and fish have some behavioral similarities, like hovering in the water column and schooling together. But anatomically they are very different (vertebrate vs. invertebrate).

So shrimp are much more closely related to lobsters than fish, since they share more anatomical features and DNA. This is why shrimp and lobsters are grouped together as crustaceans, while fish have their own distinct phylum.

The similarities between shrimp and fish are more a result of convergent evolution – adapting to similar environments, not close genetics. It’s their differences that tell the true evolutionary story.

Why It Matters How We Classify Seafood

Accurately classifying seafood isn’t just important for scientists – it also impacts how we fish, cook, and eat different species. Here are a few reasons it matters:

• Fishing regulations – Related species are often subject to similar fishing rules to prevent overfishing. Grouping shrimp and fish could lead to depletion.

• Cooking methods – Shellfish and finfish often require different cooking times and temperatures based on their anatomy and density.

• Allergies – Some people are specifically allergic to shellfish, but not finfish. Knowing which is which can prevent allergic reactions.

• Nutrition – Fish and shellfish have some differing nutrient profiles, so labeling is important for people monitoring their diet.

• Aquaculture – Farming related species together boosts efficiency. But incompatible species would decrease yield.

Properly differentiating between fish, shrimp, and other aquatic creatures helps ensure we handle them appropriately from an ecological, culinary, and health perspective.

Shrimp Are Not Fish – The Bottom Line

While fish and shrimp share an aquatic habitat, they differ significantly in their anatomy, taxonomy, and evolutionary history. Here are some key points demonstrating their differences:

• Shrimp are invertebrates; fish are vertebrates. This alone shows huge genetic differences.

• Fish have bony internal skeletons; shrimp have exoskeletons and shells.

• Fish use fins to swim; shrimp use swimmerets and tails.

• Fish breathe through gills only; shrimp use gills and respiratory sacs.

• Fish lack jointed limbs; shrimp have 10 articulate legs and pincers.

These biological differences underpin why scientists firmly classify the two into entirely separate phylogenetic groups. Fish are chordates, while shrimp are crustaceans.