Substrate - It's Importance & How To Make It

In the wild, Hermit Crabs burrow deep down into the sand dunes to safely moult. Now that they have been brought into captivity, we must provide them with a similar environment and substrate so that they can continue to safely moult and survive.

What is Substrate?

When people refer to substrate (sub) in the Hermit Crab world, we are referring to the sand mixture at the bottom of the tank.

Substrate is a vitally important aspect of a Hermit crab tank and can often mean life or death for Captive Hermit Crabs.

Too shallow and they will be forced to surface moult, too inconsistent and they won't be able to tunnel, too dry and their moult caves will collapse, too wet and they could drown, wrong products used, and they could die.

Building the right substrate may sound scary and hard, but it is actually very easy, and if done right, it only needs to be done once.

Why is deep substrate so important

In the wild, Hermit Crabs can dig down 12+ inches (30cm) into the sand to begin their moult. They need a dark environment for their moult to begin and be successful. They also need a closed off space away from predators and other Hermit Crabs to avoid being attacked while they are in such a vulnerable state.

If you don't offer deep substrate for a Hermit Crab to moult in captivity, they will likely be forced into a surface moult which is very unnatural for them and can often lead to death or complications such as limb loss.

Products needed to make your substrate

To construct your substrate, you will require the following supplies:

• Coir Peat Brick

• Play sand

• Prime Water Conditioner

• Water

• A bucket or scoop for measuring

• 2 x Large Bucket or Tub

Coir peat is readily available at Bunnings stores and gardening centers in your vicinity. It is derived from finely ground coconut husks and is a cost-effective option.

The incorporation of coir peat into the substrate is attributed to its exceptional water retention properties. This feature facilitates maintaining adequate moisture levels in the sand and ensuring the substrate's optimal consistency.

Please refrain from purchasing the following products at gardening stores for use in animal enclosures: coco peat, peat moss, coir gardening soil, and coir potting mix. These items are not recommended for such applications.

What ratio of substrate do Australian Hermit Crabs need

In Australia, we try to make our substrate as close as possible to what they have in the wild. The best way to do this is by making your substrate a ratio of 8 parts sand to 1 part of damp coir peat.

This is very easy to measure if you are not usually comfortable with ratios. Simply use your bucket or scoop and fill it 8 times with sand, and then 1 time with damp coir peat. Repeat the process until you reach the desired level.

Hermit Crab species overseas will often use the 5:1 ratio of 5 parts sand to 1 part coir peat. Our natural environment over here is a bit sandier, more of an 8:1 ratio, which is why our ratio is different for Australian Hermit Crabs compared to their overseas cousins.

How deep and why

Because Hermit crabs prefer to dig down deep to complete their moults, it is recommended to have a MINIMUM of 6 inches (15cm) of substrate. However, if you can go deeper, you should.

Setting up the substrate

• Fill a large bucket or tub with tape water and treat it with your Prime water conditioner. Break apart your coir peat brick and soak it in the water until completely soaked, making sure to break it apart so there are no dry parts left.

• Grab yourself another bucket or tub and scoop up the sand with your desired measuring device 8 times and place it into the bucket.

• Remove some of the soaked coir peat and wring it out in your hands until it is damp (not soaking wet) and measure out 1 part (this should be the same device you used to measure the sand) place it into the tub that has the sand in it. Continue with the 8 scoops of sand and 1 scoop of coir peat until you have a large mixture in the bucket.

• Using your hands, thoroughly mix the sand and coir peat together until it is completely combined. Place it into your tank and continue the measuring/mixing process until you have completely covered the bottom of the tank and have the sand mixture sitting at a minimum of 15cm. Keep in mind that your substrate will settle over time, so going a bit over 15cm is best. Use a ruler or tape measure to check the depth, the substrate should be equal in height throughout the tank. There is no need to have a shallow side and deep side. By having the entire substrate the same depth, you are offering more moulting space for your crabs.

Substrate Consistency

Your substrate should be a sandcastle consistency at all times. What does this mean? If you scoop up some substrate and firmly squish it into a ball, it should keep its shape (like a sandcastle)

You can also check the consistency by poking a finger into the substrate or pushing a straw down to the bottom of the tank up against the glass and removing it. The holes you make should keep their shape. The substrate should not look wet, only moist.

Inappropriate Substrates

It is imperative that these products are not utilized as substrate for Hermit Crabs.

These products do not facilitate the natural behavior of digging and safe moulting for Hermit Crabs. They lack the ability to retain moisture and do not provide a conducive environment for building secure caves. Utilizing these products as substrate significantly increases the likelihood of issues such as surface moulting, shell dropping due to stress, or even fatality for the Hermit Crab.

Regrettably, pet stores may promote these types of substrates as suitable options due to a lack of knowledge. The prevailing practice in pet stores often dictates the marketing of Hermit Crabs with these inappropriate substrates.

Failure to provide the correct substrate mixture will result in insufficient moisture levels in the tank, leading to dry conditions. Furthermore, the absence of safe moulting spaces can induce stress and distress in the Hermit Crabs. While these substrates may be encountered in the wild, they are not the preferred choice for Hermit Crabs to moult in their natural habitat.

Instances where Hermit Crabs seem to thrive for extended periods on these unsuitable substrates are misleading. In reality, the lack of appropriate moulting opportunities can hinder growth and lead to unnatural surface moulting or death within a year. If these products currently serve as your substrate, it is not too late to rectify the situation and provide a safe and suitable environment for your Hermit Crabs.

• Tanbark

• Calcium Sand

• Reptile Bedding

• Dirt

• Just Sand

• Just Coir Peat

• Coconut Fibre

• Rocks and Pebbles

• Coloured Sand

• Shell Grit

• Reptile Sand

What makes these substrates unsuitable for accommodating your captive hermit crabs? The aforementioned products do not provide the appropriate consistency for your hermit crab to construct its moulting cave in a safe and secure manner. Without a proper moulting cave, your hermit crab may be forced to moult above the surface, a process known as surface moulting.

Furthermore, calcium sand is a substance that solidifies upon contact with moisture. There have been numerous instances where hermit crabs have become stuck inside their shells due to the hardening of calcium sand within the shell.

Substrate - not just for moulting!

A lot of people think substrate is only for moulting, but that's not true at all. Substrate plays a much bigger part within your Hermit Crabs world. They will often dig down into the substrate to distress when they have been through a stressful ordeal such as being purchased from the pet shop, moving homes, being handled too much, being put under stress etc.

The substrate also plays a part in your humidity and heat. By having moist substrate, it will help aid the humidity within your tank and by having deep substrate, you have less air space to heat up, making it a much more cost-effective option for your electricity bill. Hermit Crabs will also dig down into their substrate to cool down if they are feeling too hot.

Adding more substrate

Alot of owners start with the right mixture and consistency for their substrate but make it far too shallow. There are no issues in topping up the substrate, but if you have Hermit Crabs down, you will need to be careful to not collapse their caves.

You can add 3cm of substrate on top of the current substrate every week. Adding to much will weigh down on the tunnels. Simply sprinkle the new substrate over the top of the current one and avoid pushing down.

Why is my substrate dry

It is very normal for the top 2-3cm of substrate to dry out. This is usually caused by the heat in the air, as well as heat emitted from lights, as long as the bottom layers of your substrate are moist, this shouldn't be an issue.

Another reason for dry substrate can be because you have either placed your heat source under the tank or below the substrate line. Both of these things should be avoided at all costs. You ONLY want to heat the air, NOT the substrate.

Avoid spraying the substrate to remoisten it. This can cause a flood.

When should I change the substrate

The answer is, if done correctly the first time, never. There are only 3 reasons for changing out your substrate, a flood, a bug infestation or if you are moving house.

You can read more about substrate emergencies such as floods and bug infestations here https://www.happyhermie.com.au/post/hermit-crab-emergencies-flooding-bug-infestation

The Coir Peat Brick needed. Purchase the BLUE packaging

• Washed play sand that is bagged

Coir Peat soaking in Primed water

Coir Peat after being broken apart and completely soaked

8 parts play sand and 1 part coir peat

Completely mixed together and placed into the tank at 15cm deep