The number of lobster species is complicated because the word “lobster” is used broadly to describe several different groups of marine life. Lobsters are ancient marine crustaceans belonging to the order Decapoda, known for their distinct body structure and economic value. To find a precise number, one must define what a lobster is taxonomically, which separates the small group of “true” lobsters from other well-known types. This confusion between common names and biological classification causes varied answers to the species count.
Establishing the Official Species Count
The definitive answer to the number of true lobsters lies within the infraorder Astacidea. This group contains all clawed decapod crustaceans, including marine lobsters and freshwater crayfish. Astacidea is distinguished by having large pincers, or chelae, on the first three pairs of walking legs, with the foremost pair being notably larger.
The “true” or clawed lobsters belong exclusively to the family Nephropidae, which includes commercial species such as the American and European lobsters. Scientists currently recognize a relatively small number of species within Nephropidae, generally cited as being between 52 and 54 extant species globally.
This small number of species forms the biological core of the term “lobster.” While the entire infraorder Astacidea contains over 780 recognized species, most are freshwater crayfish. The specific count of true lobsters remains subject to revision as taxonomic updates sometimes lead to the identification of new deep-sea species.
The Three Major Types of Lobsters
The species count increases dramatically when the two other major groups commonly called “lobsters” are included. These three groups—Clawed, Spiny, and Slipper lobsters—differ significantly in their external anatomy.
Clawed lobsters (Nephropidae) are defined by their large, asymmetrical claws used for crushing and cutting prey. This group, including the American lobster, represents the most familiar form, yet their species count remains the smallest of the three major types, at around 54 species. These true lobsters are primarily found in temperate and cold marine environments.
Spiny lobsters (family Palinuridae) contain approximately 60 or more species and are recognizable by the absence of large claws. Instead of pincers, they possess long, whip-like antennae and a carapace covered in sharp spines used for defense.
The family Scyllaridae, known as slipper lobsters, contributes nearly 90 species to the common usage of the term. Slipper lobsters are easily distinguished by their highly flattened, broad bodies and unique antennae, which have evolved into large, shovel-like plates. These three distinct families collectively account for over 200 species widely known as lobsters.
Global Habitat and Size Diversity
The various lobster species occupy a wide range of habitats and physical scales. Habitat distribution for true lobsters extends from shallow continental shelves to deep abyssal plains. For example, the American lobster is found in shallower coastal waters, while certain Nephropidae species inhabit deep-sea environments, sometimes exceeding 1,800 meters.
Spiny and slipper lobsters exhibit broad distribution, often preferring warmer, tropical and subtropical waters of the Indo-Pacific and Caribbean, residing in coral reefs or rocky areas. In contrast, many true lobsters are adapted to the colder, deeper waters of the North Atlantic and Pacific Oceans. This wide geographical spread indicates the successful adaptation of these crustaceans to nearly every marine environment.
The physical size variation among these species is impressive, ranging from the largest known arthropod to species only a few inches long. The American lobster (Homarus americanus) is the largest, with individuals known to exceed 20 kilograms (44 pounds) and a body length of 64 centimeters. Smaller deep-sea species and slipper lobsters may only measure a few centimeters in length when fully grown.