Have you ever heard of a lobster arachnid?
You may have seen joint-legged animals like scorpions, spiders, prawns, and different types of lobsters.
They look similar in appearance, but there is a distinction among them.
They may have a common ancestor. Scorpions and spiders are (arachnids), a different class of the phylum Arthropoda.
Did you consider lobsters to belong to Arachnids?
In this detailed article, we will talk about it, but let’s start with a quick answer.
Lobsters are underwater creatures with long bodies and muscular tails. They are malacostracans, not arachnids. Both belong to the same phylum, Arthropoda. Lobsters belong to the class Malacostraca within the subphylum Crustacea (crustaceans).
Arachnids, on the other hand, belong to the class Arachnida within the subphylum Chelicerata.
This means lobsters are crustaceans, while arachnids are primarily land dwellers (though some can live in water or moist environments).
However, this classification only tells part of the story. They do share some similarities despite their many differences.
Below, we’ll explore these amazing creatures and discover some amazing facts about lobsters and other arachnids.
Are Lobsters Spiders the Same or Separate? Discover the Truth About the Lobster Arachnid
Lobsters and spiders may look scary or creepy, but they belong to the same phylum, Arthropoda, the largest phylum of animals on Earth, with 80% of animals.
However, within this phylum, they belong to separate classes.
Lobsters
They are underwater crustaceans belonging to the class Malacostraca. They share the subphylum Crustacea with crabs, shrimp, and barnacles.
Spiders
These eight-legged land dwellers are arachnids belonging to the class Arachnida.
They are more closely related to scorpions, ticks, and mites.
04 main Similarities
Jointed appendages
- Both lobsters and spiders have legs with multiple segments for flexibility.
Exoskeleton
- They have a hard outer shell of chitin and calcium carbonate for protection.
Body Division
- Their bodies are divided into two main parts: a cephalothorax (fused head and thorax) and an abdomen.
Blood
- Some crustaceans, like lobsters, have a blue blood protein called hemocyanin that carries oxygen.
Differences
Legs
- Lobsters are decapods, meaning they have ten legs, while spiders always have eight legs.
Habitat
- Lobsters are aquatic, while spiders are primarily land dwellers (although some can live in water or moist environments).
Breathing
- Lobsters breathe through gills, while spiders use air sacs called book lungs.
Mouthparts
- Lobsters have mandibles for chewing, while spiders have chelicerae (modified fangs) for injecting venom and liquefying prey.
Despite their differences, lobsters and spiders are fascinating examples of the diverse adaptations of the phylum Arthropoda.
Why Not Are Lobsters Arachnids? (Biologically Explained)
Lobsters are aquatic malacostracans that differ from arachnids.
Lobsters belong to the class Malacostraca subphylum Crustacea, and arachnids, like spiders and scorpions, are in the class Arachnida under the subphylum Chelicerata.
Lobsters are adapted to water, while arachnids are mainly terrestrial, though some can live in moist areas.
Below, you can read about the main biggest differences between them. Read on!
Classification
Classification systems in taxonomy help divide animals into Kingdom, Phylum, Subphylum, Class, Order, Suborder, Family, Genus, and Species.
According to biological classification, arachnid animals (spiders, scorpions, harvestmen, spiders, mites, ticks, horseshoe crabs, etc.)
It belongs to the class Arachnida of the subphylum Chelicerata within the main phylum Arthropoda.
Lobsters (related to crabs and prawns) belong to the class Malacostraca, subphylum Crustacea, a very diverse group that includes sandhoppers and lobsters.
interestingly, Insects are phylogenetically are also considered crustaceans
within the phylum Arthropoda.
A paper also published on 05 August 2015 explores the concept of “Pancrustacea,” which groups insects and crustaceans due to their close evolutionary relationship.
So, Even though they share the same species and in the animal Kingdom, they have a lot of similarities. However, due to their different subphylums and classes.
Chelicerates and crustaceans diverged and had differences 38 million years before the appearance of the first land plants.
It is like how we are closer to sharks than a crab is to a spider.
Please refer to the chart of the phylum Arthropoda for more information.
Eyes
If you compare lobsters and arachnids, you’ll easily see one of their biggest differences: their eyes.
Lobsters are malacostracans and have compound eyes. These eyes consist of hundreds or thousands of tiny light-sensitive units called ommatidia.
Function: Each ommatidium detects light and creates a portion of an image. Together, they form a mosaic image with a wide field of view.
Scientific research shows that lobsters cannot see sharp images, but their compound eyes excel at detecting motion, especially in dim light.
Lobsters rely on this ability and their sense of smell to judge their surroundings.
Arachnids possess simple eyes, known as ocelli, with a single concave lens, receiving light for visual processing.
Unlike insects’ compound eyes, arachnids’ limited ocelli result in poor visual acuity, relying on touch and vibration senses.
Yet, some, like jumping spiders, excel with specialized retinas and movable ocelli.
The number of Eyes is also a big difference; how?
Lobsters
Two stalked eyes.
Arachnids
Varying numbers of eyes, typically from two to eight, depending on the species.
Examples
Scorpions
6 to 12 eyes
Tarantulas
Eight eyes – four small primary eyes in the front center and four larger secondary eyes on the sides
Breathing
There is a difference between them in the respiratory system. Lobsters breathe through gills.
Gills are feathery organs beneath their carapace (shell) that extract oxygen from water.
- Location: Water flows over the gills through openings at the base of their walking legs.
- Out of water: Lobsters can survive for a short period outside of water, but only if their gills remain moist.
This is because some oxygen exchange can still occur, but it could be more efficient in water.
Arachnids
Arachnids don’t have gills or lungs like mammals. They use a respiratory system called book lungs.
These flattened, sac-like organs with thin, leaf-like folds increase surface area for gas exchange.
- Trachea: Book lungs are connected to a network of air tubes called trachea that deliver oxygen throughout the body.
- Water: Most arachnids cannot breathe underwater because their book lungs require air.
However, there are some exceptions, like diving bell spiders, which can trap air around their bodies to create a temporary air bubble for breathing.
Appendages
This is a big difference between lobsters and arachnids.
Lobsters
Lobsters have five pairs of walking legs.
The first pair of legs in lobsters with claws are big claws.
They use their legs for walking, eating, and other things.
Lobsters use their legs to move, protect, eat, make babies, and clean themselves.
Some legs help them taste and feel things.
Arachnids
Arachnids usually have four pairs of walking legs.
Their front two pairs are special:
Fangs
for eating and protection.
Claw-like things for grabbing food, sensing, or mating.
They use their legs to move, protect themselves, eat, and make webs if they are spiders.
Understanding how their legs differ helps us see how they live in their homes.
Lobsters, you know, are aquatic animals and cannot survive out of water. They live on the seafloor in a variety of habitats, including:
Rocky areas: provide lobsters with crevices and holes for shelter.
Sandy bottoms: Some lobsters burrow in the sand to hide.
Kelp beds and eelgrass meadows: These underwater forests offer lobster protection and food sources.
Temperature
Different lobster species have varying temperature preferences.
Clawed lobsters (like the American lobster) generally prefer cooler waters and are found in the North Atlantic Ocean.
Spiny lobsters live in warmer waters and are commonly found in the Caribbean Sea.
Arachnids like Spiders: Spiders are terrestrial creatures that can be found in almost every habitat except the oceans.
However, they may not be able to survive in extremely cold regions like the polar regions due to the harsh temperatures. Especially lobsters can be cannibalistic in captivity if not fed them well. So always feed them a proper diet.
Antennae
Lobsters have two sensitive antennae (or antennules) covered with hairs on the front of their heads.
They use it to smell, locate food, and sense danger. Their size and length can vary from species to species.
Arachnids (such as scorpions and spiders) don’t have antennae.
They rely on other sensory organs, such as pedipalps (modified appendages near the mouth) and sensory hairs on their legs, to navigate their environment.
Interestingly, spiny lobsters use their long antennae for more than just sensing their surroundings.
They can also be used for protection against predators. Lobsters with large claws have shorter and thinner antennae.
Lobster Arachnid Origins? What Are Lobsters Related to?
Lobsters have two main groups of relatives, which makes them related to other sea creatures.
The first one is crustaceans, the closest group, including familiar animals like shrimp, crabs, crayfish, and prawns.
They share many characteristics with lobsters, such as having a hard outer shell (exoskeleton), ten legs (decapods), and living in water also pass through lobster molting or ecdysis process.
Arthropods: This is a broader phylum that includes crustaceans like lobsters but also insects, spiders, scorpions, and mites.
Cockroaches and lobsters are also related but closely related.
Cockroaches are insects and lobster crustaceans, both in the same species.
They are close to frogs and humans related to the phylum Chordata.
Lobsters and cockroaches have ancestors that date back 440 million years, and humans and frogs share ancestors that date back 370 million years.
Is A Lobster An Arachnid?
Lobsters are not arachnids. They are underwater animals with long bodies and strong tails ues their pee for communication.
They belong to a group called malacostracans, which are different from arachnids.
Lobsters and arachnids are part of the Arthropoda family but are put into different groups within it.
Lobsters are in the class Malacostraca, while arachnids are in the class Arachnida.
Crabs, shrimp, and crayfish are examples of crustaceans like lobsters, while spiders, scorpions, and mites are examples of arachnids.
One big difference between them is their body structure. Crustaceans usually have ten legs and a hard outer shell.
Arachnids have eight legs, and special mouthparts called chelicerae for eating.
Most arachnids live on land, while crustaceans usually live in water, although there are exceptions.
Similarities Between Lobsters and Arachnids: What Makes The Lobster Arachnid Connection Interesting
While researching oceanic animals, I discovered that lobsters and arachnids, though belonging to different classes within the same phylum (Arthropoda), share several similarities in their body structure.
Body Segmentation
- Both lobsters and arachnids have segmented bodies.
- They share similar body structures like cephalothorax and abdomen.
- The cephalothorax houses key features like antennae, eyes, mouthparts, and legs.
- The abdomen plays a role in movement and escape.
Exoskeleton
Lobsters and arachnids have an exoskeleton made of chitin, a complex sugar that provides rigidity and protection.
Chitin can be hardened with calcium carbonate in some species for extra strength.
Internal Skeleton
They lack an internal skeleton and depend on the exoskeleton for support and structure.
Exoskeletons can’t grow with the animal; they undergo molting (ecdysis) to shed the old exoskeleton and produce a new, larger one.
Juveniles molt more frequently, every few days or weeks, to accommodate rapid growth.
Adults molt less often, once a year or every two years for females, depending on the species.
You can read my other blog, where I explain the true nature of lobster roach biologically, Just read on…
Jointed legs
Lobsters and arachnids are arthropods, a large phylum containing nearly 80% of all animal species.
They share a key feature: jointed legs. However, their hard exoskeleton helps protect them and can limit the flexibility of their appendages.
Amazingly, their jointed legs allow for movement despite the exoskeleton.
Both lobsters and arachnids can bend their appendages at the joints.
This technique, combined with muscles attached to the exoskeleton on either side of the joints, allows for remarkable control of their limbs.
FAQs(Frequently Asked Questions)
Are lobsters related to Spiders, Crabs, and Shrimp?
Lobsters are distantly related to spiders, crabs, and shrimp within the Phylum Arthropoda. Lobsters, crabs, and shrimp belong to Crustacea, while spiders belong to Chelicerata. They diverged millions of years ago.
Are shrimp lobsters insects?
No. Lobsters and shrimp are not insects, but they’re closely related crustaceans. They share common features, suggesting a close evolutionary link.
How many legs do lobsters have?
A lobster has ten appendages, eight of which are true legs used for walking and two large claws, or pincers, for grasping and feeding.
Are lobsters related to Scorpions? (Same ancestors)?
Lobsters and scorpions share a common ancestor in the Arthropoda phylum, but they diverged early.
Lobsters belong to Crustacea, close to crabs and shrimp, while scorpions belong to Arachnida, closer to spiders and ticks.
Are lobsters related to cockroaches?
Yes, lobsters and cockroaches are related, but not closely. They both belong to the Arthropoda phylum but are classified into different classes.
Lobsters are in Crustacea (with crabs and shrimp), while cockroaches are in Insecta (with insects).
Resources:
1. The structure and classification of the Arachnida
2. Linking Insects with Crustacea: Physiology of the Pancrustacea: An Introduction to the Symposium
