No, shrimp and lobsters are not bugs. They are crustaceans, a group of animals that also includes crabs and crayfish.
Crustaceans have a hard exoskeleton, jointed legs, and multiple body segments, which are characteristics that are different from insects, which have a chitinous exoskeleton, three body parts, and six legs.
But you might also have heard that lobsters were once called the “cockroaches of the sea” thanks to their abilities to scavenge food and their historically poor reputation.
But if you want to widen the description to include any “creepy crawly” with six legs or more, then sure, shrimps and lobsters, along with many other crustaceans, could be called bugs of the sea.
Science has specific descriptions for animals and their classes, so there isn’t room for confusion.
Considering what could be a bug in general terms, we’ll discover precisely what shrimps and lobsters are and how they differ from the insects and other arthropods many of us think of as bugs.
Lobsters, shrimps, and other crustaceans belong to the class crustacea, while insects belong to the class insecta.
Both insects and crustaceans are part of the phylum arthropoda, but they have differences in anatomy.
Shrimps and lobsters may be referred to as “sea bugs” in common language, but the term “bug” is more accurately used for insects with six legs or more.
Are Shrimps and Lobsters Bugs of the Sea?
To answer, “are lobsters bugs?” we must consider what we mean by the word.
If you mean an insect, then no, shrimps and lobsters are crustaceans.
But try asking your friends what a bug is. You might be surprised at the range of answers you get!
What is a Bug?
Depending on who you talk to, a bug could be any insect.
It could also include, more broadly, any critter with more than six legs like a spider or a centipede.
In a different context, doctors even call some disease-causing germs superbugs, and hopefully, your seafood isn’t that!
But, if you know your entomology, you’ll know that, scientifically, a true bug is a specific set of insects known as order Hemiptera.
Scientists use words that have specific meanings to avoid any confusion.
But in the real world, we often talk a bit more generally. We’re understandable, just not quite as precise.
The Museum of New Zealand says that “the word “bug” means a creepy crawly in everyday conversation. It refers to land arthropods with at least six legs.”
In the book “The Handy Bug Answer Book,” Gilbert Waldbauer notes that bugs are not insects but that “when most people use this word, they have in mind multi-legged creatures.” He suggests that although the phrase is loosely used, extending it to legless creatures like slugs and snails “stretches the word too much.”
So, generally, when most of us say “bug”, we mean one of the many-legged beasties, such as insects, spiders, beetles, moths, or centipedes.
Shrimps and lobsters are crustaceans, and they live in the sea, so if you were thinking of bugs only as land animals, they’re not included.
However, as we’re going to see, crustaceans, including shrimps and lobsters, sit inside the large phylum Arthropoda, just like the more generally named land bugs.
So, following this logic, why not commonly call shrimps, lobsters, and their other relations bugs of the sea?
Indeed there are already other locally named sea bugs, such as the Balmain bug, Moreton Bay bug (slipper lobsters), and the mudbug (a name for crayfish).
So, let’s agree that it’s ok to call shrimps and lobsters sea bugs, but in doing so, try and work out more precisely what they are.
What Are Shrimps and Lobsters?
Shrimps and lobsters are crustaceans.
Crustacea are a large group (a subphylum) of arthropods under the class mandibulata that contains over 67,000 species.
Examples of crustaceans include tiny copepods, mantis shrimps, fish lice, krill, barnacles, and the enormous Japanese spider crab.
Most crustaceans are found in underwater environments, although a few are land-based such as terrestrial hermit crabs, sandhoppers, and woodlice.
The most common crustaceans, like crabs, lobsters, crayfish, prawns, and the most well-known shrimp are found in the order of decapod crustaceans.
Decapod means “ten-footed,” and there are about 15,000 crustacean species, of which about half are crabs and around 3,000 are shrimps.
What is a Shrimp?
Are shrimps insects? No, shrimps are swimming crustaceans with long abdomens and antennae and typically look a little like miniature lobsters.
With such a massive number of species, it should be no surprise that shrimps vary dramatically in their size.
One of the smallest shrimp orders, the Anostraca fairy shrimps range from 6–25 mm (0.24–0.98 in) long.
The mantis shrimp of the order Stomatopoda at the other end of the spectrum can grow as large as 38 cm (15 in).
Most shrimps are found in saltwater environments, including seas beneath the Antarctic ice and in harsh hypersaline lakes. However, there are also many freshwater species.
Eating insects may be growing in popularity, but, at least in the Western world, it’s nothing like as prevalent as enjoying shrimp.
But are shrimps the bugs of the sea? Well, they’re multi-legged. Most are decapod crustaceans with ten pairs of appendages.
Shrimps are also omnivores that will scavenge and eat almost anything. This certainly sounds like a bug to us!
What is a Lobster?
Like shrimp, the answer to “are lobsters insects?” is a firm no.
Lobsters are a family of large marine crustaceans.
Are lobsters the bugs of the sea? Like shrimps, we think the larger multi-legged critters might also fit the bill for this general term.
The most well-known lobsters are those from the crustacean family Nephropidae. These are the clawed lobsters and the ones that you’ll recognize from the best restaurants.
There are also spiny and slipper lobster crustaceans that don’t have the big claws and are often even referred to as bugs locally.
Most lobster have thick muscular tails on their long bodies, and they’ll live in burrows in the seabed or inside rocky crevices.
Like shrimp, lobster are omnivores and will scavenge as well as eat live prey.
It’s even been known for lobsters to be cannibalistic if their population gets too large and there’s not enough food to go around.
What are the Main Differences Between Crustaceans and Insects?
Having told you that shrimps and lobster aren’t insects, let’s look at some of the most important differences that mean they can’t be categorized as traditional “bugs.”
Insects are divided into three distinct body parts; the head, thorax, and abdomen.
Meanwhile, in shrimps and lobster, the first two parts, the head, and thorax, are joined together as one part called a cephalothorax.
Additionally, the abdomen of shrimps and lobster are segmented, unlike insects, where it is one single part. For example, a shrimp’s abdomen is divided into six segments.
All members of the phylum Arthropoda, including insects and crustacea like shrimps and lobsters, have a hard exoskeleton.
This waterproof shell provides structure, support, and protection to the animal organs and the attachment points for the muscles.
For insects, the exoskeleton is made from chitin, a tough natural polymer.
However, the chitin is thickened compared to most insects and toughened with calcium carbonate in crustaceans.
So, if the animal you’re looking at has a hard calcium exoskeleton (like a shell), then it’s probably a crustacean.
Sticking out of the heat of the critter is another crucial difference between insect land bugs and shrimps and lobsters.
On an insect, you’ll only see one pair of antennae, whereas, on crustaceans, you’ll see two pairs in total.
There may be two long antennae and two much shorter (antennules and antennae), so you might have to look closely. However, on shrimps and lobsters, there’ll be four there somewhere.
It may sound obvious when talking about underwater animals, but lobsters and shrimp don’t have wings!
Almost all insects have wings. The only exceptions are fleas, lice, silverfish, and firebrats.
However, wings are not always immediately visible as insects have often evolved not to use them.
For example, on a beetle, the wings have become the hard outer covering on the back of the animal.
So, while they’re not always obvious, if you can see evidence of wings, you can be sure it’s an insect you’re looking at.
Another excellent way to tell the difference between insect bugs, shrimps, and lobsters is to count their jointed legs.
On land, you can readily tell the difference between insects with six jointed appendages and spiders (arachnids) and scorpions with eight legs.
Decapod crustaceans, including shrimps and lobsters, have at least ten legs.
Lobsters are a bit tricky as they have eight walking legs. However, the large claws are also biologically regarded as legs and make up the decapod count.
Shrimps have numerous appendages, although not all are obvious as legs.
Up front, there are three pairs of maxillipeds (meaning “jaw feet”) that the shrimp uses to feed.
Then there are five pairs of pereiopods on the thorax carapace which look more like traditional legs. They’re then followed down the segmented abdomen with pleopods that are used for swimming.
If that all sounds complicated, you only need to remember that if you see ten legs or more, it’s a crustacean in front of you.
How Crustaceans and Insects Breathe
Unsurprisingly, insects and sea crustaceans breathe differently as they live in the air or underwater.
Insects breathe through holes in their exoskeletons called spiracles that use an internal tracheal system of tubes to transport oxygen.
Crustaceans, like shrimp, have exposed gills and use their legs to pump oxygenated water over them.
In the case of the lobster, the gill cavities are protected underneath their shells, and the animal continually pumps water into them.
Insects have a reasonably straightforward digestive system, and they excrete waste products as uric acid containing dry fecal pellets once water and nitrogenous products have been absorbed.
Crustaceans are a bit more complicated and have developed glands to control their excretory system.
Lobsters even have structures that function as kidneys in their heads and will excrete ammonia as their waste byproduct.
Where They Live
Finally, the most obvious difference between insects and crustaceans is where they live.
Almost every insect is found exclusively on land (or in the air). Crustaceans are almost exclusively found underwater, apart from a few exceptions like the woodlouse.
In insects, the stages follow a straightforward pattern: egg, larvae, pupa, and adult.
In crustaceans, the larvae from eggs have multiple phases, including the nauplius, zoel, and then the post-larval stage.
The post-larval phase is distinctive as it looks very much like a miniature version of the adult.
In insets, it’s common for the larvae to look entirely different from the adult animal.
Are There Any Similarities Between Crustaceans and Insects?
Having been through all the differences, we should ask why shrimps and lobsters, like insects, are often called bugs.
If we step back from the differences we’ve discussed, they look pretty similar.
They all have numerous legs, antennae, rigid exoskeletons, jointed legs, and segmented bodies. They just differ a bit in the details.
So compared to other obviously different animals like mammals on land or fish underwater, it’s understandable to group these critters together.
Are Shrimps, Lobsters, and Insects Related? (Are Lobsters Related to Bugs?)
Biologically, insects and crustaceans, including shrimps and lobsters, belong to the phylum arthropoda.
It’s just that insects are separated into the class insecta, while shrimps and lobsters are in the class crustacea.
Each class has its specific defining characteristics, but it’s certainly easy to see that there is more in common to all these “bugs”.
Indeed, DNA evidence suggests that of all the arthropods, insects and crustaceans are most closely related to one another.
It seems fair to call shrimps and lobsters sea bugs if you think of land insects and other similar beasties all as bugs.
Are There Any True Underwater Insects (Other Aquatic Arthropods)?
Having asked, are lobsters sea bugs, are there any underwater insects that we could also give the name to?
Aquatic insect species, including dragonflies and mosquitoes, have aquatic larval stages with gills.
There are even diving insects, like some beetles, that will hunt for their food underwater.
However, as terrestrial insects breathe air as a gas, adult insects struggle to live entirely underwater like crustaceans. Although some species have developed clever solutions, including trapping air bubbles on their bodies or using breathing “straws.”
The only insect regarded as a marine species is the sea skater, which remains firmly on the water surface.
Are Lobsters Bugs? – Conclusion
So, are lobsters bugs? Are shrimps bugs?
Well, if you’re being scientifically correct, no. The only true bugs are the insects known as order Hemiptera.
Additionally, if you generally meant insects when referring to bugs, shrimp and lobsters are crustaceans that are not the same.
However, we think it’s reasonable to be a bit more flexible.
Lobsters and shrimps, insects, spiders, beetles, centipedes, and many other creatures are all ultimately arthropods.
They’re all multi-legged, have an exoskeleton, typically scavenge for food, and have a similar look about them.
So, while it might be more common to refer to the general terrestrial creepy crawlies as bugs, we think it’s reasonable to at least call shrimp, lobster, and other similar creatures sea bugs if you want to.
However, if we’re in a seafood restaurant, we’ll stick to ordering our shrimp and lobster clearly so we don’t get any nasty surprises!
British-born Dan has been a scuba instructor and guide in Egypt's Red Sea since 2010.
Dan loves inspiring safe, fun, and environmentally responsible diving and particularly enjoys the opportunity to dive with sharks or investigate local shipwrecks.
When not spending time underwater, Dan can usually be found biking and hiking in Sharm's desert surroundings.