Invertebrate pets: Handle with the utmost care

Not all invertebrates can be sexed according to their appearance or their mouthparts, as in spiders. Some have a life cycle of four stages: cockroaches lay eggs, snails are hermaphrodites and certain stick insects lay fertile eggs without male intervention. The breeding cycle has to be studied with full cognisance of all the needs for success.

One has to learn how to handle or restrain each individual invertebrate without causing injury to both parties. Snails, millipedes and crabs are not a problem if carefully handled. Some large spiders may respond to bad handling by biting or releasing urticarial hairs from the top of their bodies, which can induce a severe inflammatory skin reaction. If there are doubts with handling or if there is a fear of being hurt, then the invertebrates can be viewed in transparent glass containers or on a sheet of plastic where there is no opportunity for escape – even gentle handling with gloves can be worthwhile.

Some veterinarians have perfected anaesthesia, or hypothermia can be applied by keeping the creature at 4°C for up to thirty minutes. They can become sluggish, easier to handle but are not pain-free.

It is important to study each invertebrate at length and macroscopically so that any sign of decreased activity, alteration in movement, colour change, deformity, swelling or discharge can be detected readily. One must know the normal to detect the abnormal. While there is very little data on cell counts in haemolymph or bacteria flora of mouthparts of certain spiders, some laboratory work has been extrapolated from discharges found from orifices of a spider or haemolymph from snails.

Viruses have been diagnosed in moths and butterflies, but can occur across the range in invertebrates. Bacterial infections are common in invertebrates, but the difficulty lies in diagnosing whether the bacteria found is normal or pathogenic in any given species. A bacterium of veterinary importance is the one causing “foulbrood” in European honeybees. In some countries certain antibiotics have shown a degree of success, and affected hives have to be burnt by the apiarists. In some forms of the disease ropey threads are found in the hive or mortality in larvae. These various forms of “foulbrood” are notifiable to the government authorities.

Fungal infections are a significant problem throughout the arthropod world and diagnosing it is a problem. Certain crickets suffer high mortality in a humid environment due to the overgrowth of fungus and fungal spores. One fungus, sometimes found in silkworms, can affect over five hundred invertebrate species.

Invertebrates can be stressed by excessive handling. The failure to adapt to captivity will affect feeding. This will induce nutritional diseases, failure to thrive and cause premature death.

In invertebrates relatively low down on the evolutionary ladder certain similar nerve structures have been found as in the higher forms of life and while the level of pain differs vastly, one should still be concerned about appropriate analgesia for surgical procedures.