Animals lacking a spine or any internal bone structures are classified as invertebrates. They possess an exoskeleton, or outer shell, which they shed as they grow. This process is called molting.
At some point in the past, people started keeping these strange and interesting animals as pets, and now a whole hobby has been built around keeping them.
Unlike with many traditional pets, you don’t have to take pet invertebrates for walks, train them or provide very large enclosures.
The 3 Best Pet Invertebrates for Beginners
Here is a list of 3 commonly available invertebrates that can be great pets:
#1 Pet Invertebrates for Beginners: Hermit Crabs
Hermit crabs are one of the most common first pets, but many aren’t given the proper care to survive very long.
In captivity, hermit crabs can live 10–20 years under the right living conditions. They thrive in high humidity, along with a varied diet and companions.
These crabs are surprisingly social and do well in groups. Watching their interactions is one of the joys of keeping them.
- A 20-gallon aquarium will provide decent room for your pet hermit crab to roam.
- If you’re adding more members to the group, a 55- to 75-gallon aquarium will work much better.
- Hermit crabs need access to both fresh and saltwater.
- The salt must be the kind made for marine fish.
- Stick to natural shells, preferably the same size or a little larger than what the crabs are currently wearing.
- Avoid painted or decorative shells — they’re known to cause illness in the crabs.
- To create a deep, moist substrate, use silica-based sand and coco husk.
- This substrate also provides a place for them to burrow into it from time to time and molt underground.
Humidity and Temperature
- Keep the humidity level at 75–85% at all times.
- A comfortable temperature range is 75–85 F.
Lighting and Heating
- If your house is on the cool side, you can add an under-tank heater to one side of the tank to add warmth for the inhabitants.
- A fluorescent tube light should suffice for viewing, and provide a day and night cycle for the crabs.
- Avoid commercial foods — hermit crabs are sensitive to preservatives and other additives.
- A diet of varied veggies, fruits, leaves, flowers, crushed coral and calcium will benefit all crabs.
- They love meaty foods, including dried insects, cooked meat and eggs.
- Some hermit crabs enjoy handling, while others do not. Try to keep your hand flat and allow them to crawl on you to avoid any pinching.
- Some crabs will actively climb your hands and clothes, and they appear to like exploring a bit. Just keep handling out of the tank to 10–15 minutes — the humidity outside the tank isn’t really comfortable for the crabs.
- For more detailed information on caring for hermit crabs, visit this great care sheet.
#2 Pet Invertebrates for Beginners: Giant Millipedes
Giant millipedes are multi-legged arthropods that are relatively friendly. There are multiple species available of varying sizes, and some can live 7–10 years.
Some millipedes sport lovely color schemes. Their docile nature makes them a great choice as a more easily handled pet invertebrate, and they don’t move too fast either.
If they feel threatened, millipedes will curl into a tight spiral and secrete an irritating liquid from pores in their body. It can be harmful to your eyes or mouth, so wash your hands if this occurs. Some species may have a higher toxicity, so make sure to correctly identify what millipede species you want to keep as a pet.
You can house giant millipedes with their own kind, and they will generally get along fine. They will even breed readily if both males and females are present. If you have breeding adults, make sure you can find homes for the little ones.
- A 10- to 15-gallon tank will comfortably house a couple of millipedes.
- Millipedes like to burrow, so provide a 3- to 4-inch depth of substrate. A peat/soil mixture will work well. You can add sphagnum moss on top.
- Make sure there aren’t any pesticides in the soils you use.
- Keep the substrate damp, not wet, with regular misting.
Temperature and Humidity
- A good temperature range is 75–85 F, and a small dip at night should be fine.
- Maintain a high humidity of 75–80%.
Lighting and Heating
- No special lighting is required.
- For heating, you can use an under-tank heater to add warmth to one side of the tank.
- Keep a shallow dish of water for your pet millipedes in the tank.
- Clean the water dish and refill it often.
- Millipedes are herbivores that eat mostly decaying plant matter.
- You can feed your pet millipedes vegetables cut into small pieces. Soft fruits and veggies work, too. If the food starts to decay, that’s all right — they prefer it that way.
- Add some leaf litter for them, too. Just make sure it’s free of pesticides or other bugs.
#3 Pet Invertebrates for Beginners: Mexican Redknee Tarantulas
Mexican Redknee Tarantulas are among the more hardy and docile tarantula species, and they tolerate some handling.
Reaching a leg span of about 5 inches, Mexican Redknees are colorful and long-lived tarantulas — a few have reached their 20s in captivity.
Unlike tree-dwelling species, the Redknee is terrestrial and needs more floor space than height with respect to housing.
- A terrestrial container or terrarium should adequately house 1 tarantula.
- Include a lid — these spiders can climb.
- A plastic terrarium-style critter-keeper will do just fine.
- Adding an overturned flower pot or driftwood will provide hiding spots.
- Use horticultural vermiculite (not insulation type) or Eco Earth. Both hold humidity well and are made specifically for pets.
- It’s best to add a layer of at least 2 inches.
Temperature and Humidity
- A steady 70–78 F is a good range.
- A heating source may not be needed depending on your climate.
- Humidity should be maintained at 50–60% in the tank. It is thought that raising the humidity during the molting process helps them.
Lighting and Heating
- No lighting is needed.
- Heating isn’t necessary either, unless you live in a cold climate.
- Supply a small, shallow dish of water for the tank.
- Place 1–2 pebbles to prevent drowning of prey items.
- Clean and refill often.
- Feed your Mexican Redknee Tarantula properly sized crickets, superworms or roaches once a week.
- The size of prey and the frequency at which you feed will depend on the age and size of the tarantula.
- Determine handling according to how comfortable or stressed the tarantula is. Some keepers forego handling to reduce the chance of stress to the animal.
- Another potential reason for avoiding handling is the irritating hairs the tarantulas can flick off their abdomens when they feel threatened. These little hairs can irritate eyes, nose and skin.
- There is also the fact that these spiders can bite.
- Some tarantulas do well with a little handling, but take care not to drop yours — this can lead to injury or death. For such large spiders, tarantulas are still delicate.
Watch these amazing hermit crabs in the wild:
Where to Find These Pet Invertebrates for Beginners
Local and online vendors may carry the species of pet invertebrates you’re looking for. (Make sure they are reputable sources.)
Connect with message boards relevant to what you’re interested in, and they may be able to point you in the direction of both breeders and vendors. You may also find some invertebrate pets needing to be rehomed by their keepers.
Keeping Pet Invertebrates
Invertebrates can add a unique insight into their world when in captivity, whether kept as pets or in a collection.
Many of their instinctual behaviors remain unchanged, and keepers can observe several events during their life cycles that would otherwise be hidden. You learn each individual animal’s preferences and personality.
A novice keeper can gain knowledge and experience with beginner species and eventually graduate to keeping more difficult ones. The hobby can culminate in keeping and breeding species usually reserved for the more advanced keeper.