Isopod: All You Need to Know for a Fascinating Discovery

Isopods are fascinating marine invertebrates belonging to the crustacean group, which also includes creatures like crabs and shrimp. They display remarkable morphological diversity, ranging in size from a few micrometers to half a meter in length, and can be found both in aquatic and terrestrial environments.

These critters are easily recognized by their flattened, many-segmented bodies, and compound eyes, not on stalks. Isopods have two pairs of antennae, with one pair being significantly larger than the other. Their seven pairs of walking legs are all quite similar in appearance, while their five pairs of double-parted pleopods serve as gills in aquatic isopods.

Understanding Isopods

Types of Isopods

Isopods are a diverse group of crustaceans that include both aquatic and terrestrial species. Examples of common isopods include:

  • Pillbugs
  • Sowbugs
  • Woodlice

Crustacean Characteristics

Isopods share common characteristics, such as:

  • Flattened top-to-bottom bodies
  • Seven segments with a pair of walking legs per segment
  • Head, thorax, and abdomen not immediately distinct
  • Eyes are compound and not on stalks
  • Two pairs of antennae
  • Mouthparts for chewing

Wild Isopods vs. Pet Isopods

There are key differences between wild isopods and those kept as pets:

Wild Isopods Pet Isopods
Natural habitat Controlled environment
Predator-prey relationship No predators
May face challenges like pollution Protected from environmental challenges

In both environments, they serve as decomposers, breaking down organic material, which helps keep ecosystems balanced.

Isopod Care and Enclosure

Setting up an Isopod Enclosure

Isopods are popular as they are easy-to-care-for pets and beneficial for vivarium habitats. To set up an enclosure, choose a container with a secure lid, such as a plastic terrarium or a glass tank. The size of the container may vary, but it should allow space for the isopods to comfortably roam and breed. Add a few pieces of wood, bark, or leaf litter for hiding spots and adequate cover.

Substrate and Soil Requirements

Isopods need a nutrient-rich substrate to create a healthy habitat. A mix of the primary ingredients below should work well:

  • Peat moss
  • Coco coir
  • Rotted wood or leaves

Additionally, to maintain the optimal pH, add crushed eggshells, cuttlebone, or limestone to the substrate.

Creating Ideal Moisture and Ventilation Conditions

Proper moisture and ventilation are crucial for isopod health, as they need to be kept moist to breathe. Here are some tips to manage both:


  • Maintain one side of the enclosure moist and the other side relatively drier
  • Mist the enclosure lightly with water regularly without soaking the entire substrate


  • Provide small air holes in the container for continuous air exchange
  • Prevent mold buildup by avoiding excessive moisture

Keep these tips in mind for maintaining a thriving isopod habitat and ensure their proper care and enclosure management.

Feeding and Diet

Food Sources for Isopods

Isopods are known to eat a range of materials such as:

  • Moss
  • Bark
  • Algae
  • Fungi
  • Decaying material (including leaf litter)

Fungi on some trees provide necessary nitrogen for isopod diets1.

Supplementing Nutrition with Calcium and Protein

Isopods have specific nutritional requirements that need to be supplemented with:

  • Calcium
  • Protein
Food Source Calcium Protein
Vegetables Yes No
Fruits No No
Invertebrates Yes Yes
Animal waste Yes Yes
  • Vegetables like carrots can be a good source of calcium
  • Invertebrates and animal waste provide both calcium and protein

Feeding isopods a well-balanced diet is crucial for their health and growth.

Breeding Isopods

Understanding Isopod Mating and Reproduction

Isopods, commonly known as pill bugs or sow bugs, have unique mating and reproduction habits. Males transfer sperm packages to the females, who then store them in a special pouch called a marsupium.

Isopods exhibit sexual dimorphism, which means that males and females look different. For example, males tend to be larger with stronger rear limbs, while females have more developed marsupium pouches.

Establishing a Suitable Environment for Breeding

To successfully breed isopods as pets, it’s essential to create a proper environment for them. Here are some points to consider:

  • Substrate: Use a moist mixture of peat moss, coco coir, and decaying leaves.
  • Moisture: Ensure a balance between wet and dry areas in the enclosure.
  • Temperature: Maintain a temperature of 70-75°F (21-24°C).
  • Hiding spots: Provide plenty of hiding spots such as bark and wood pieces.

When setting up an isopod colony, remember to:

  • Start small: A modest-sized colony will ensure that the population grows at a manageable rate.
  • Mix genetics: Introduce isopods from multiple sources to promote genetic diversity.
Pros of Breeding Isopods Cons of Breeding Isopods
Easy to care for and low-maintenance Overpopulation if not managed properly
Help to break down organic matter Some species may become invasive if released into the environment

By following these guidelines and keeping the colony well-maintained, you’ll be on your way to successfully breeding your own isopod pets.

Specific Isopod Species and Traits

Porcellio Scaber

Porcellio Scaber, also known as the common rough woodlouse, is a widespread terrestrial isopod species. It is characterized by its dark brown or gray color and distinctive rough texture.

Some traits of Porcellio Scaber:

  • Primarily feeds on decaying plant materials
  • Prefers moist habitats
  • Can be found under rocks, logs, and leaf litter

Armadillidium Vulgare

Armadillidium Vulgare, commonly known as the pillbug, is another popular terrestrial isopod. They are also known as “roly-polies” because they can roll into a tight ball when threatened.

Key features of Armadillidium Vulgare:

  • Can roll into a ball for defense
  • Consumes decaying organic matter
  • Found in moist environments similar to Porcellio Scaber

Dairy Cow Isopods

Dairy Cow Isopods (Porcellio Laevis) are a popular choice among isopod enthusiasts due to their striking black and white pattern, resembling a dairy cow. They are larger than many isopod species.

Characteristics of Dairy Cow Isopods:

  • Attractive black and white pattern
  • Larger than Porcellio Scaber and Armadillidium Vulgare
  • Useful in bioactive vivarium settings

Rubber Ducky Isopod

The Rubber Ducky Isopod (Cubaris sp.) is a highly sought-after exotic isopod species. These unique isopods have a distinct appearance that resembles a rubber duck, with a yellow “head” and darker “body.”

Rubber Ducky Isopod features:

  • Unique and visually appealing appearance
  • Rare and highly sought after by collectors
  • Requires specialized care compared to other species
Isopod Species Size Habitat Appearance Popularity
Porcellio Scaber Small Terrestrial Rough, brown/gray Common
Armadillidium Vulgare Small Terrestrial Smooth, gray Common
Dairy Cow Isopod Medium Terrestrial Black and white Popular
Rubber Ducky Isopod Medium Terrestrial Yellow and dark Sought after

Additional Uses and Significance

Isopods as a Cleanup Crew

Isopods play a crucial role in the decomposition of leaf litter and contribute significantly to nutrient cycling and soil ecosystem services. Their ability to break down organic matter makes them excellent natural cleaners for bioactive setups.

  • Animals benefiting from isopods: Frogs, geckos, and other inhabitants of bioactive setups.
  • Maintenance: Isopods help reduce maintenance by consuming dead plant matter and waste products.

Prey for Other Animals

Many predators, such as frogs and geckos, feed on isopods, making them an essential part of the food chain. Dwarf isopods, in particular, make an ideal food source for smaller animals as they are small and reproduce rapidly.

  • Advantages: Natural prey, easy to culture, rich in nutrients.
  • Disadvantages: May escape enclosures, not suitable for all sizes of animals.

Bioactive Setups

Isopods are invaluable in creating and maintaining bioactive enclosures for various animals, making it a self-sustaining ecosystem. They work well with other cleanup crew members, such as springtails, to create a balanced environment.

Isopod Culture

Isopod cultures are relatively simple to establish and maintain. Here are key points for a successful isopod culture:

  • Ideal temperature: Around 70-75°F
  • Humidity: Keep moist but not wet
  • Food: Decaying plant matter, vegetables, and reptile-safe leaf litter
  • Breeding: Provide hiding spots and adequate space for populations to grow

Comparison Table: Isopods vs. Other Cleanup Crew Members

Aspect Isopods Springtails
Size Vary in size, can be larger Smaller, less noticeable
Food Organic matter, leaf litter, vegetables Fungi, mold, decaying matter
Prey Many animals benefit from isopods as prey Fewer animals prey on springtails
Maintenance Reduce maintenance in bioactive setups Also help with waste management


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Reader Emails

Over the years, our website, 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 – Aquarium Isopod from Australia


Subject: freshwater aquarium isopod?
Location: Australia
March 13, 2015 8:04 am
Hi, I found this bug in my tank after adding some new plants. I think it might be an isopod of sorts but am unsure as to what type it is. I have it currently in a cup of water with some moss and the small mystery snail that also came with the plants. I’m too worried to keep it in the tank in case it is a parasitic bug that could harm my fish. If the bug is completely harmless please let me know so that I can add it back int the tank instead of them being stuck in a small cup. If it helps, I have noticed that it tends to roll into a ball when it feels threatened. Thanks.
Signature: weilmanu

Aquatic Isopod
Aquatic Isopod

Dear weilmanu,
We agree that this is some aquatic Isopod and we cannot guarantee that it will not cause problems in your aquarium.  We would not recommend introducing it to your aquarium.

Aquatic Isopod
Aquatic Isopod

Letter 2 – Australian Isopod: Slater


what bug is this?
Hi Bugman,
I was wondering if you know the name of this bug. I found it last week near a river in sydney. From what i remember the bug is about 3-4cm long. Thank you in advance.

Hi Phylis,
This is some type of Isopod. We found a photo of a marine specimen from Australia that looks very similar. A common name is Australis is Slater.

Letter 3 – Crustaceans: Marine Amphipods


Identification Request: found on Malibu Beach, Southern Califonia
Location:  Malibu, California
July 23, 2010 5:33 pm
These were collected at night the week of the 4th of July by my teenage son on the beach in Malibu, California. They are shown in a regular five gallon bucket and are about an inch long excluding antenna.
During the day I noticed similar looking, but much smaller, bugs jumping on the sand. The color camouflages them well. The small ones were far too fast for me to photograph.
Attached, a small photo. High res one (URL may change):
Eli the Bearded

Marine Amphipods

Hi Eli the Bearded,
Good name.  These are some type of Crustacean.  We believe they are Marine Isopods, but we cannot find a matching photo online.  Perhaps our readership can assist.

Marine Amphipods

Karl makes a Correction
These look like marine amphopods (Amphipoda), specifically beachhoppers (Amphipoda: Talitridae).  They are probably Megalorchestia californiana, California Beach Fleas (aka: California Sand Fleas, California Beach Hoppers, Long-horned Beach Hoppers), or perhaps another closely related species.  K

Letter 4 – Another Isopod


Hello…nice and informative website. I had a bug in my bath tub this morning that I was trying to identify. It looks similar to another photo that someone took and you said there bug was a Crustacean. Is the bug I found the same thing?

Yes, Ryan,
You have an isopod.

Letter 5 – BeachHopper: Marine Amphipod


Subject: Found at Crissy Field
Location: Chrissy Field Beach, San Francisco
June 2, 2015 11:19 am
Hey Mr Bugman, what’s my bug?
Signature: Griffin

Beach Hopper

Hi Griffin,
This is a Marine Amphipod commonly called a BeachHopper, probably
Megalorchestia californiana.  Your submission will post live to our site later in June while we are away from the office.

Thanks for getting back to us.  We found this guy on the beach and he was resourceful, so we really wanted to know what he was.
Thank you!

Letter 6 – Fast Isopod


Hey Bugman,
I found this bug in the house this morning. I live in Boise Idaho and I have never seen one of these before. It looks like a "Rolly-Polly", but was MUCH faster, and did not curl up into a tight ball. This is the only one I found. I tried to look it up on the internet and also in the National Audubon Society Field Guide with no luck. Can you help me out???
Ryan J
Boise ID.

Hi Ryan,
You are correct. It is a type of Isopod, a Crustacean, and is related to the common Pill Bugs you know as Rolly-Pollies. They generally do not do any damage unless they are very plentiful.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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.

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  • 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.

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5 thoughts on “Isopod: All You Need to Know for a Fascinating Discovery”

  1. These look like marine amphopods (Amphipoda), specifically beachhoppers (Amphipoda: Talitridae). They are probably Megalorchestia californiana, California Beach Fleas (aka: California Sand Fleas, California Beach Hoppers, Long-horned Beach Hoppers), or perhaps another closely related species. K


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