Where Do Crustaceans Live: A Friendly Guide to Their Habitats

Crustaceans are a diverse group of creatures that primarily inhabit aquatic environments. These fascinating creatures can be found in various ecosystems, ranging from oceans and freshwaters to damp soil, where they play essential roles in maintaining the ecological balance.

You may be familiar with some crustaceans, such as crabs, lobsters, and shrimp that inhabit coastal habitats and are popular in culinary dishes. However, crustaceans are not limited to these well-known marine animals. For example, copepods and isopods can be found in freshwaters, taking on crucial roles in aquatic food chains.

In this article, we’ll explore the diverse habitats where crustaceans live, showcasing the incredible adaptability of these intriguing creatures. We will uncover the various ecosystems they occupy, and how these environments contribute to their unique characteristics, offering insight into their interesting lives.

Crustaceans: An Overview

Crustaceans belong to the phylum Arthropoda and are a diverse group of invertebrate animals. Some examples of crustaceans include crabs, lobsters, and shrimp. Here are some common features of crustaceans:

  • Invertebrate animals
  • Part of the subphylum Crustacea
  • Exoskeleton for protection
  • Distinct body sections: head, thorax, and abdomen

As arthropods, crustaceans have various appendages such as antennae for sensing their environment and specialized mouth parts for feeding. They also possess jointed legs, which help them navigate their surroundings.

Most crustaceans live in aquatic environments, though a few can be found in terrestrial habitats. Of the nearly 67,000 aquatic crustacean species, only 10% occur in freshwater environments.

A comparison of three common crustaceans:

Crab Lobster Shrimp
Appendages 10 legs 10 legs 10 legs
Antennae 2 pairs 2 pairs 2 pairs
Head Cephalothorax Cephalothorax Cephalothorax
Thorax Fused with head Fused with head Fused with head
Abdomen Distinct section Distinct section Distinct section

Though they share many similarities, crustaceans can vary considerably in size, habitat, and behavior. Keep this overview in mind while delving deeper into the fascinating world of crustaceans, as it provides a foundation for understanding the diversity and adaptations of these remarkable creatures.

Classification of Crustaceans

Crustaceans belong to the phylum Arthropoda and are a diverse group of invertebrates. The subphylum Crustacea includes various species such as crabs, lobsters, shrimp, barnacles, amphipods, isopods, and krill. Here we will briefly discuss their classification.

Classes and Species

Crustaceans are divided into several classes, some of which are:

  • Cephalocarida: Primitive crustaceans with a small number of species.
  • Branchiopoda: Includes water fleas, fairy shrimp, and other species with gills on their feet.
  • Remipedia: A small group of rare, blind, cave-dwelling crustaceans.
  • Ostracoda: Small crustaceans resembling clams, commonly known as seed shrimp.
  • Cirripedia: Contains the sessile and free-living barnacles.
  • Malacostraca: The largest and most diverse class, comprising species like crabs, lobsters, and shrimp.

Decapods, Amphipods, and Isopods

Within the class Malacostraca, you’ll find the order Decapoda which includes popular crustaceans like crabs, lobsters, and shrimp. While the order Amphipoda involves species like beach fleas, and the order Isopoda contains species like pillbugs and woodlice.

In general, Decapods have:

  • 10 legs
  • A hard exoskeleton
  • Two major body segments: the cephalothorax and abdomen

Comparatively, Amphipods and Isopods have:

  • A flattened body from side to side
  • Different leg types for various functions

Krill and Euphausiacea

Krill are small, shrimp-like crustaceans found in every ocean and are part of the order Euphausiacea. They play a crucial role in marine ecosystems, serving as an essential food source for many marine animals.

To summarize, crustaceans come in a variety of shapes and sizes, ranging from tiny krill to massive lobsters. They thrive in diverse habitats, showcasing their adaptability and crucial role in the ecosystem.

Habitats of Crustaceans

Crustaceans are predominantly aquatic creatures, but some species have also adapted to live in terrestrial environments. They can be found in various aquatic habitats such as sea and freshwater environments like oceans, lakes, and rivers.

In marine ecosystems, crustaceans inhabit the water column and the seafloor, from the intertidal zone to the deep sea. You might find creatures like crabs, shrimp, and lobsters living in these habitats. In freshwater habitats, only about 10% of crustacean species can be found, including crayfish, water fleas, and pill bugs. These freshwater crustaceans can be found in rivers, streams, and lakes.

While the majority of crustaceans are aquatic, some have adapted to life on land. Terrestrial crustacean species are relatively rare, but they do exist. For example, pill bugs or woodlice are crustaceans that you might find in your garden, under rocks or in damp areas.

In summary:

  • Aquatic crustaceans:
    • Marine habitats: crabs, shrimp, lobsters
    • Freshwater habitats: crayfish, water fleas, pill bugs
  • Terrestrial crustaceans: pill bugs (woodlice)

The wide variety of habitats that crustaceans inhabit show their incredible adaptability and their importance in diverse ecosystems. You’ll discover these fascinating creatures in various environments, making them an interesting subject to learn about and observe.

Aquatic Crustaceans

You may find various types of crustaceans in both freshwater and marine environments. Some common aquatic crustaceans include the Japanese spider crab, American lobster, and barnacles.

Marine crustaceans like shrimps and prawns live in salty ocean waters. A few examples are:

  • Japanese spider crab: They are known for their massive leg span, which can reach up to 12 feet from claw to claw.
  • American lobster: You might be familiar with their delicious taste, and they are mostly found in the Atlantic Ocean.

Freshwater crustaceans like fairy shrimp, seed shrimp, and water fleas dwell in rivers, lakes, and ponds. For example:

  • Fairy shrimp: These delicate creatures live in seasonal pools, laying eggs that can survive during dry periods.
  • Seed shrimp: They can act as filter-feeders, removing particles from the water and contributing to the ecosystem.

Some crustaceans like fish lice are parasites that latch onto fish, while others, such as barnacles, attach themselves to hard surfaces like rocks or ships.

Here is a comparison table of a few crustaceans:

Name Environment Mobility Size
Japanese spider crab Marine Free-swimming Up to 12 feet leg span
American lobster Marine Free-swimming Up to 20 inches in length
Barnacles Marine Sessile 0.4 to 2.7 inches in diameter
Fairy shrimp Freshwater Free-swimming 0.2 to 1.4 inches
Seed shrimp Freshwater Free-swimming Up to 0.2 inches

While exploring aquatic environments, make sure to observe these fascinating creatures in their natural habitats!

Terrestrial Crustaceans: Woodlice and Beyond

Woodlice, commonly known as pill bugs or roly-polies, are fascinating creatures. While you might typically associate crustaceans with aquatic environments like oceans and rivers, woodlice are an exception, thriving in terrestrial habitats. They are among a small group of crustaceans that have adapted to life on land, making them a unique example within the subphylum Crustacea.

One interesting aspect of woodlice is their walking legs. Unlike insects, which possess six legs, woodlice have seven pairs of walking legs. These legs help them navigate through diverse environments, from your garden soil to a forest floor. A key difference between woodlice and insects is their exoskeleton, which is calcium-rich and requires frequent molting to accommodate their growth.

Woodlice play a vital role in their ecosystems, particularly as part of the soil food web. Here’s a quick list of their ecological benefits:

  • Decomposers: Woodlice break down leaf litter, aiding in nutrient recycling.
  • Prey: They serve as a food source for various animals, such as birds, frogs, and spiders.

Although woodlice occupy a fascinating ecological niche, they’re not the only terrestrial crustaceans. Some other examples include beach hoppers found along sandy shorelines and desert-dwelling seed shrimp. Each of these terrestrial crustaceans contributes to their respective ecosystems, highlighting the incredible adaptability and diversity of the Crustacea subphylum.

Crustaceans in the Food Web

Crustaceans play a crucial role in the food web, acting as both predators and prey. They come in various shapes and sizes, making them suitable for consumption by a wide range of organisms.

In the ocean, crustaceans such as copepods and amphipods feed on algae and plankton. By doing this, they help maintain the balance of these primary producers, preventing overgrowth in the ecosystem. In turn, small crustaceans become a primary food source for a variety of fish and other marine vertebrates.

Larger crustaceans like crabs and lobsters are scavengers, feeding on dead fish and other organic matter that fall to the ocean floor. They play an essential role in breaking down and recycling nutrients in the marine ecosystem. As predators, they also control populations of smaller organisms like mollusks and small fish. At the same time, these larger crustaceans become prey for fish, sea birds, and marine mammals like seals and whales.

A few examples of predator-prey relationships involving crustaceans are:

  • Whales feed on krill, which are small shrimp-like crustaceans.
  • Fish such as cod and haddock consume smaller crustaceans like amphipods.
  • Seagulls prey on crabs, breaking their shells open to access the meat inside.

Crustaceans have evolved various ways to protect themselves as well. Some species have developed hard outer shells to deter predators, while others rely on camouflage or have adapted to unusual environments to avoid competition and predation.

Parasites are also part of the crustacean’s life in the food web. For instance, certain types of fish lice attach themselves to fish, feeding on their blood and tissues. Crustaceans like barnacles may also serve as hosts for parasitic species.

Remember, crustaceans make up a vital part of the marine food web, contributing to a healthy ecosystem through their roles as predators, prey, and scavengers. By understanding their relationships and interactions with other organisms, you can appreciate their importance in supporting biodiversity in the ocean.

Life Cycle of Crustaceans

Crustaceans are fascinating creatures that live in a variety of environments, from the depths of the ocean to freshwater habitats. In this section, we’ll briefly explore their life cycle, touching on important aspects such as eggs, larvae, and molting.

The life cycle of crustaceans begins with the laying of eggs. Female crustaceans either release these eggs into the water, or they carry them around until they hatch. Some crustaceans, like certain crabs and shrimp, even have specialized appendages for carrying their eggs, ensuring their safety before they hatch.

Once hatched, the young crustaceans emerge as larvae. These larvae often differ drastically in appearance from their adult counterparts. They go through a series of molts, shedding their exoskeletons, as they grow and mature. This process, known as instar, involves shedding and regrowing an exoskeleton that is more suitable for their growing bodies.

During the molting process, crustaceans are incredibly vulnerable, as their new exoskeletons have not yet hardened. This leaves them exposed to predators and other environmental threats. But with each molt, they will gradually gain features and adopt the appearance of an adult crustacean.

As crustaceans grow, their reproductive systems develop, and they eventually become sexually mature. Most crustaceans reproduce sexually, but there are also cases of hermaphrodites within the crustacean community. For instance, some barnacles possess both male and female reproductive organs, increasing their chances of successful reproduction.

In summary, the life cycle of crustaceans involves:

  • Laying eggs (either free-floating or carried by the female)
  • Hatching and emergence of larvae
  • Instar stages, including shedding exoskeletons
  • Development of reproductive systems
  • Sexual reproduction (or hermaphroditism)

As you can see, the life cycle of crustaceans is a complex and fascinating process that allows these unique creatures to adapt and survive in their diverse environments.

Adaptations of Crustaceans

Sensory Adaptations

Crustaceans have developed various sensory adaptations to survive and thrive in their habitats. They rely on their eyes to detect light in their surroundings. For example, many crustaceans have compound eyes with numerous facets that enable them to perceive a large field of vision.

Another vital sensory adaptation is their antennules. These hair-like appendages are crucial for detecting chemical and tactile signals in the water, helping them to find food and avoid predators.

Structural Adaptations

Some critical structural adaptations in crustaceans include features such as their mandibles, maxillae, carapace, gills, and telson. These parts play essential roles in their survival.

  • Mandibles and Maxillae: These mouthparts are designed for efficient feeding. Mandibles help to crush and grind food, while maxillae help in food manipulation and transport to the mouth.
  • Carapace: A hard, protective covering or exoskeleton that shields the cephalothorax (head and thorax region) of many crustaceans, providing defense against predators and physical damage.
  • Gills: These structures allow crustaceans to extract oxygen from the water, enabling them to breathe and live in various aquatic environments. The gills’ efficiency may vary depending on the water’s salinity and temperature.
  • Telson: The telson is the last segment of the crustacean’s abdomen, which serves as a tail for some species. It helps with propulsion in swimming species and can also be used for defense or digging in burrowing crustaceans.

Crustaceans living in sessile habitats, such as barnacles, display a different set of adaptations. These organisms possess a hard, calcified shell and modified legs to adhere to surfaces, allowing them to withstand strong currents and wave action.

Your understanding of crustacean adaptations will help you appreciate the incredible diversity and resilience of these fascinating invertebrates.

Crustaceans: Importance in Ecosystems

Crustaceans play a vital role in marine ecosystems. They come in various sizes, from microscopic planktonic organisms to large, highly prized species like lobsters and crabs. Thanks to their diversity, they serve as a critical link in food chains and contribute to the overall health of their habitats.

You might be surprised to learn that crustaceans have a fossil record dating back millions of years. This rich history reveals how they have evolved and adapted to different environments over time. Today, many crustaceans are essential in maintaining the balance of their ecosystems. For instance, they help recycle nutrients by breaking down organic matter and support the growth of aquatic plants.

Some notable crustacean characteristics include:

  • Varied body structures and sizes
  • Adaptability to both aquatic and some terrestrial habitats
  • Significant contributors to Earth’s biodiversity

While crustaceans provide numerous benefits to ecosystems, their populations can also be impacted by external factors like climate change. It can affect their reproductive cycles, growth rates, and habitat suitability. As a result, the stability of ecosystems they inhabit may also be at risk. Therefore, efforts to protect and conserve these fascinating creatures are essential in preserving our planet’s biodiversity.

Remember, the more you learn about these amazing creatures, the better you’ll understand their importance in maintaining healthy, thriving ecosystems. So, keep an eye out for crustaceans on your next beach adventure, or even in your backyard – they’re an essential part of the world you live in!

Crustaceans Across the Globe

Crustaceans are diverse creatures that inhabit various environments worldwide. Their habitats range from the deepest ocean floors to the shores of the Arctic and Antarctic regions. For example, in Japan, one can find crustaceans like crabs and shrimp living both in the ocean and on land.

Crustaceans have different preferences when it comes to their diets. Some species eat plants and algae, while others are carnivorous predators feasting on fish or other crustaceans. A few examples of crustaceans’ dietary habits include:

  • Hermit crabs prefer scavenging on plant and animal matter.
  • Mantis shrimp are known for their aggressive hunting skills and powerful punches.
  • Water fleas feed primarily on algae in freshwater environments.

In comparison to other marine creatures, crustaceans display a range of adaptability and versatility. They can survive in vastly different environments and temperatures, allowing them to thrive all around the globe. Here are just a few examples:

  • Snow crabs can survive in the freezing waters of the Arctic Ocean.
  • Coconut crabs live on tropical islands and can climb trees to find food.
  • Copepods are tiny crustaceans commonly found in both cold and warm waters of various oceans.

Now that you have a glimpse of the fascinating world of crustaceans, enjoy exploring more about these incredible creatures and the diverse habitats they occupy.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Land Hoppers from Australia

 

What bug is this?
Location: Sydney Australia
April 9, 2012 2:44 am
We found hundreds of these on the floor of our family room (all dead) next to two walls – from corner to corner.
Shiny gold/brown with a soft shell. Look like a giant flea.
Climate – warm. Fairly dry after 2 years of wet.
Signature: Mike of Epping

Land Hoppers

Dear Mike of Epping,
These terrestrial Crustaceans or Amphipods are native to Australia and they are known as Land Hoppers.  Most of our reports come from California and occasionally UK and Florida where the species has been introduced at the beginning of the twentieth century, or perhaps even earlier, most likely with the introduction of Australian plants that were imported to grow in foreign gardens.  In North America, Land Hoppers are known as House Hoppers or Lawn Shrimp.  They live and thrive in damp soil where they generally go unnoticed due to their drab coloration.  After heavy rains however, they often migrate in great numbers to drier areas like garages and homes where they promptly die and turn pink or red in color.  You may read more about Land Hoppers on the Victoria Museum website and on University of Florida IFAS website where their dampness requirements are explained as:  “Terrestrial amphipods live on the surface (top 1/2 inch) of mulch and moist ground. After rains, large numbers of amphipods can migrate into garages or under the doors of houses. There they soon die. Amphipods do not have a waxy layer on their exoskeleton as do insects. They lose or gain moisture from their environment. Too much of a water loss results in desiccation while too rapid a gain is also lethal. This is why they migrate out of rain-soaked soil to drier areas where they usually end up dying anyway. Most species are active at night.”

Letter 2 – Gooseneck Barnacles wash up on beach in Denmark

 

Subject: Strange animal found in Denmark
Location: Hvide Sande, Denmark
November 9, 2013 4:55 pm
Hi,
Just browsed through my pictures and found this one. I remembered that I was trying to find out what that is unsuccessfully. Looks like a mixture between an animal and seashells.
Thanks for your time.
Signature: Aquila

Gooseneck Barnacles
Gooseneck Barnacles

Dear Aquila,
This looks to us to be a small cluster of Gooseneck Barnacles, marine crustaceans that attach themselves to rocks and other surfaces where they lead a sedentary existance, feeding on plankton that drifts their way.  This group must have gotten detached, perhaps by severe wave action, and washed up on your shore.  Here are some photos from North Island Explorer and Oceana.

Dear Daniel Marlos,
Thanks a lot, a long time mystery solved 🙂
Aquila

Letter 3 – Oriental Hornets attack Ghost Crab in Oman

 

Air attack by hornets on crab
In Oman recently, observed some hornets attacking a crab which was defending a piece of discarded food on the beach. Three hornets ended up attacking together from different directions. The crab just swiped at them with its big claw. The hornets gave up in the end. Hope the pictures are of interest.
John Jackson

Hi John,
Wow, what action photos you have sent us. These are Oriental Hornets, Vespa orientalis, and they are social wasps. We found a website that identifies them, lists the distribution as northern africa, western asia and madagascar, and gives other information about them. We are not sure what type of crab it is and we haven’t the time to research that right now.

Update (12/03/2007) crab vs. hornet
that has to be the funniest picture I have ever seen! It’s like David and Goliath. I guess the hornets thought it was worth the try. I’m sure the crab was laughing! happy holidays
Lee Weber
Nottingham PA

Hi Lee,
We agree that these photos are quite amazing. We were in a big rush to post them this morning before going to work.

Update: (12/05/2007) The crab and the oriental hornets
Hi Daniel,
The crab in those really great pictures is a species of Ghost Crab, genus Ocypode. They are called ghost crabs because at least some of the species are so well camouflaged that they are pretty much invisible on the sand until they move, which is often very rapidly indeed! In the Caribbean they come out of their burrows towards the end of the day. I don’t know which species this would be, as there are apparently 5 different species in the genus in Oman. All the very best,
Susan Hewitt

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Land Hoppers from Australia

 

What bug is this?
Location: Sydney Australia
April 9, 2012 2:44 am
We found hundreds of these on the floor of our family room (all dead) next to two walls – from corner to corner.
Shiny gold/brown with a soft shell. Look like a giant flea.
Climate – warm. Fairly dry after 2 years of wet.
Signature: Mike of Epping

Land Hoppers

Dear Mike of Epping,
These terrestrial Crustaceans or Amphipods are native to Australia and they are known as Land Hoppers.  Most of our reports come from California and occasionally UK and Florida where the species has been introduced at the beginning of the twentieth century, or perhaps even earlier, most likely with the introduction of Australian plants that were imported to grow in foreign gardens.  In North America, Land Hoppers are known as House Hoppers or Lawn Shrimp.  They live and thrive in damp soil where they generally go unnoticed due to their drab coloration.  After heavy rains however, they often migrate in great numbers to drier areas like garages and homes where they promptly die and turn pink or red in color.  You may read more about Land Hoppers on the Victoria Museum website and on University of Florida IFAS website where their dampness requirements are explained as:  “Terrestrial amphipods live on the surface (top 1/2 inch) of mulch and moist ground. After rains, large numbers of amphipods can migrate into garages or under the doors of houses. There they soon die. Amphipods do not have a waxy layer on their exoskeleton as do insects. They lose or gain moisture from their environment. Too much of a water loss results in desiccation while too rapid a gain is also lethal. This is why they migrate out of rain-soaked soil to drier areas where they usually end up dying anyway. Most species are active at night.”

Letter 2 – Gooseneck Barnacles wash up on beach in Denmark

 

Subject: Strange animal found in Denmark
Location: Hvide Sande, Denmark
November 9, 2013 4:55 pm
Hi,
Just browsed through my pictures and found this one. I remembered that I was trying to find out what that is unsuccessfully. Looks like a mixture between an animal and seashells.
Thanks for your time.
Signature: Aquila

Gooseneck Barnacles
Gooseneck Barnacles

Dear Aquila,
This looks to us to be a small cluster of Gooseneck Barnacles, marine crustaceans that attach themselves to rocks and other surfaces where they lead a sedentary existance, feeding on plankton that drifts their way.  This group must have gotten detached, perhaps by severe wave action, and washed up on your shore.  Here are some photos from North Island Explorer and Oceana.

Dear Daniel Marlos,
Thanks a lot, a long time mystery solved 🙂
Aquila

Letter 3 – Oriental Hornets attack Ghost Crab in Oman

 

Air attack by hornets on crab
In Oman recently, observed some hornets attacking a crab which was defending a piece of discarded food on the beach. Three hornets ended up attacking together from different directions. The crab just swiped at them with its big claw. The hornets gave up in the end. Hope the pictures are of interest.
John Jackson

Hi John,
Wow, what action photos you have sent us. These are Oriental Hornets, Vespa orientalis, and they are social wasps. We found a website that identifies them, lists the distribution as northern africa, western asia and madagascar, and gives other information about them. We are not sure what type of crab it is and we haven’t the time to research that right now.

Update (12/03/2007) crab vs. hornet
that has to be the funniest picture I have ever seen! It’s like David and Goliath. I guess the hornets thought it was worth the try. I’m sure the crab was laughing! happy holidays
Lee Weber
Nottingham PA

Hi Lee,
We agree that these photos are quite amazing. We were in a big rush to post them this morning before going to work.

Update: (12/05/2007) The crab and the oriental hornets
Hi Daniel,
The crab in those really great pictures is a species of Ghost Crab, genus Ocypode. They are called ghost crabs because at least some of the species are so well camouflaged that they are pretty much invisible on the sand until they move, which is often very rapidly indeed! In the Caribbean they come out of their burrows towards the end of the day. I don’t know which species this would be, as there are apparently 5 different species in the genus in Oman. All the very best,
Susan Hewitt

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

8 thoughts on “Where Do Crustaceans Live: A Friendly Guide to Their Habitats”

  1. wow, i just have seen this bugs in my living room in guarne ( Antioquia, Colombia) They are found in tropical countries? Im wondering.. they say they are native to Australia.

    Reply
    • Though native to Australia, Land Hoppers are invasive in Southern California where they are known as Land Shrimp or House Hoppers. According to BugGuide: “introduced into New Zealand, the British Isles, Florida and California.” It is possible they have been introduced to Colombia as well.

      Reply
  2. I live in La Ceja, Antioquia and it has rained heavily the past month and every morning I find these near the sliding glass doors. Curious to what they are and how to kill them. But they are easily swept up because they are dead. Thanks for the information. I was afraid they were termites or something serious. I also have a lot of spiders.

    Reply

Leave a Comment