An ideal substrate is one that is absorbent, digestible if swallowed, inexpensive and aesthetically pleasing. Selection must be tailored to the particular needs of the individual species (e.g. burrowing or desert species may require sand which is usually not suitable for other species). | An ideal substrate is one that is absorbent, digestible if swallowed, inexpensive and aesthetically pleasing. Selection must be tailored to the particular needs of the individual species (e.g. burrowing or desert species may require sand which is usually not suitable for other species). |