Lobsters are iconic crustaceans that have captivated people’s imaginations for centuries. With their large front claws and armored bodies, they are instantly recognizable. But do these marine invertebrates have scales like fish?
If you’re short on time, here’s a quick answer to your question: No, lobsters do not have scales. Instead, they have a hard protective exoskeleton.
In this comprehensive article, we’ll take an in-depth look at lobster anatomy and biology to understand why lobsters lack scales. We’ll examine their evolutionary history, body structure, growth process, and more. Read on to learn all about whether lobsters have scales!
Lobster Evolutionary History and Taxonomy
Crustaceans Evolved Before Fish
Lobsters and other crustaceans have a fascinating evolutionary history that predates the emergence of fish. Crustaceans are arthropods, meaning they have an exoskeleton, segmented bodies, and jointed appendages.
The earliest arthropod fossils date back to the Cambrian Period over 500 million years ago, while the earliest fish fossils emerged in the Ordovician Period around 450 million years ago.
This means lobsters and other crustaceans were thriving in Earth’s oceans for tens of millions of years before the first fish came onto the scene. In fact, some scientists believe arthropods like trilobites were among the first complex organisms to evolve eyes, giving them an evolutionary head start in adapting to ocean environments through enhanced vision and predation.
So while fish dominate the oceans today, lobsters exist as “living fossils” that represent an ancient branch of life that evolved and adapted long before the first scales sprouted.
Lobsters Classified as Decapod Crustaceans
Taxonomically, lobsters belong to the Kingdom Animalia, Phylum Arthropoda, Subphylum Crustacea, and Superorder Eucarida. More specifically, they are classified as decapod crustaceans, along with shrimp, crabs, and crayfish.
“Decapoda” means “ten feet” and refers to their five pairs of thoracic legs. These legs enable lobsters to walk along the seafloor and grasp prey. Other distinctive decapod features include a carapace (hardened shell section), stalked eyes, anterior mouthparts, and a muscular abdomen or tail.
Lobsters comprise the infraorder Astacidea within decapods. They are most closely related to reef lobsters (family Enoplometopidae) and squat lobsters (family Chilenophoberidae). There are numerous lobster families, including Nephropidae (clawed lobsters) and Palinuridae (spiny lobsters).
The American lobster (Homarus americanus) and European lobster (Homarus gammarus) belong to the Nephropidae family. Their nearest relatives are the Norway lobster (Nephrops norvegicus) and the Cape lobster (Homarus capensis) of southern Africa.
So while lobsters share many traits with other decapods, they also have unique evolutionary adaptations like enlarged front claws that distinguish them as close cousins rather than direct ancestors on the crustacean family tree.
Lobster External Anatomy and Body Structure
Hard Exoskeleton Instead of Scales
Unlike fish that have scales, lobsters have a hard external skeleton called an exoskeleton. This protective exoskeleton covers the entire outer surface of the lobster’s body. It provides support, protects the soft inner body parts, and prevents water loss.
The exoskeleton is made up of a complex crystalline polysaccharide called chitin that is also found in the cell walls of fungi and the hard outer coverings of insects.
The lobster’s exoskeleton is divided into segments joined together by flexible membranes. This segmentation provides flexibility and allows the lobster to curl its tail underneath its body for protection.
Each body segment has a pair of appendages attached to it, including the legs, claws, antennae, and parts of the tail. Between 17-19 segments make up the lobster’s body.[1]
Lobsters periodically shed their rigid exoskeletons in a process called molting as they grow bigger. Young lobsters may molt up to ten times in their first year, while older lobsters only molt once every year or two. Immediately after molting, the new soft shell rapidly absorbs water and expands.
Within hours, the shell begins to harden and take on its protective qualities again.[2]
Segments and Appendages
Each segment of the lobster’s body has a pair of appendages attached to it that enable the lobster to sense, move, and function effectively in its ocean habitat. Here is an overview of some of the lobster’s key body parts and appendages:
- Antennae – Act like “feelers” to help the lobster locate food and navigate
- Eyes – Compound eyes at the end of eyestalks detect movement and light
- Mouthparts – sharp mandibles for cutting up food
- Claws – Crushing claws for defense and for grabbing prey. Lobsters can regenerate lost claws after molting.
- Walking legs – Allow the lobster to walk along the ocean floor and swim backwards quickly by curling and flapping its tail
- Swimmerets – Fine hairs under the tail to circulate water over the gills and carry eggs in females
The lobster’s segmented body gives it great flexibility to access the nooks and crannies of the ocean floor. Each jointed appendage moves independently, enabling the lobster to stand upright, walk or swim in multiple directions, and grasp things from many angles.
The lobster’s hardy exoskeleton, legs, claws, antennae, and tail form a remarkably adaptable suit of armor that enables it to thrive on rocky and sandy sea bottoms from frigid New England to the warm Caribbean waters.
The Lobster Life Cycle and Molting Process
Molting Allows Growth
Lobsters, like all crustaceans, grow by a process called molting where they shed their hard exoskeleton and produce a new, larger one. Molting occurs many times throughout a lobster’s life, beginning soon after it hatches from an egg.
Without this ability to molt, lobsters would be unable to increase in size as they aged.
During molting, lobsters hide until their new shell has hardened enough for protection. This process of shedding the old shell, growing a soft new shell, then hardening the new shell is complex and requires a lot of energy.
It leaves lobsters vulnerable to predators which is why they hide away in a shelter during this time. The frequency of molting decreases as the lobster ages.
The Stages of the Lobster Life Cycle
There are three main stages to a lobster’s life cycle: larval lobster, adolescent lobster, and adult lobster.
Larval Lobster Stage: A female lobster carries eggs under her tail for 9-12 months before they hatch into tiny larval lobsters. These larvae float freely in the ocean currents for several weeks, molting and growing until they reach the post-larval stage.Adolescent Lobster Stage: At this point, the young lobster settles to the sea floor and takes shelter among rocks or reefs where it continues to molt and grow over several years. During this long stage, adolescent lobsters change coloration, develop claws, and transition into maturity.Adult Lobster Stage: Lobsters are considered mature adults once they reach reproductive size, which varies by species. At 5-8 years old for American lobsters or 20+ years for giant ocean lobsters, they will mate and produce a new generation of offspring.
To summarize, lobsters grow from tiny free-floating larvae into bottom-dwelling juveniles before developing into reproductive adults. They increase in size throughout these life stages by periodically shedding their rigid shells through an energy-intensive process called molting.
Understanding this unique aspect of lobster biology allows scientists to support healthy and sustainable lobster populations.
Comparing Lobsters to Other Crustaceans and Fish
Crustaceans Lack Scales
Like all crustaceans, lobsters lack scales. Instead, they have a hard exoskeleton shell that provides protection and structure. Specific to lobsters, their exoskeleton contains calcium carbonate which gives them incredible strength to withstand the pressure in the deep ocean (up to 350 pounds per square inch!).
Scales are unique anatomical features found only on certain animals – mostly fish species. Scales grow as an external skin layer providing flexible & lightweight armor. Since crustaceans shed their entire outer shell as they grow, scales wouldn’t be practical.
Shedding allows essential growth in crabs, shrimps, crayfish, and lobsters.
The armored anatomy of lobsters and relatives reflects an evolutionary path distinct from aquatic animals with scales and fins like fish. Next we’ll compare some key differences to fish.
Fish Have Scales and Other Key Differences
Fish represent a unique branch of vertebrate animals specialized for life in water. Various kinds of scales compose a defining anatomical feature of most fish species. Fish scales provide flexible, breathable, lightweight protection unlike thick crustacean shells.
We can summarize some other key contrasts between fish and shellfish like lobsters:
Fish | Lobsters |
Vertebrates (have a backbone) | Invertebrates |
Breathe using gills | Breathe using gills and small leg paddles to circulate water |
Most have scales | Exoskeleton shell instead of scales |
Swim by body/tail movement | Walk along sea floor |
Live in saltwater and freshwater | Saltwater only |
Beyond anatomical differences, fish and lobster life cycles have unique aspects. Lobsters hatch from eggs as tiny planktonic larvae drifting in ocean currents before becoming juvenile lobsters. Most fish hatch from eggs ready to swim and hunt.
While shellfish like lobsters and scaled fish represent very different forms of aquatic life, they can coexist and thrive in the same vital seafloor habitats like kelp forests and coral reefs. Maintaining healthy oceans allows protection of critical ecosystems benefiting all marine life forms – whether exoskeleton or scale-covered!
Conclusion
In summary, lobsters do not have scales on their bodies. As crustaceans, they diverged evolutionarily from bony fish long ago and developed distinct anatomical features like a hard external skeleton. Molting allows lobsters to grow by shedding their rigid exoskeletons periodically.
While fish rely on scales for protection and flexibility, the armor-like shells of lobsters and related crustaceans serve a similar function. The next time you crack open a lobster tail, you can be certain that there are no scales to be found on these fascinating marine animals.