The life of a hermit crab is a mysterious question. This is because very less is known about the internal workings of the crab physiology and their ideal lifespan in the wild. However, a general rule of hermit crab lifespan is that the lifespan of hermits is directly proportional to the molting patterns of the crabs. The molting is a process of continuous growth of the hermit crabs during when the crabs shed their exoskeleton and regenerate the lost body parts of their body. Generally, the older hermit crabs molt more frequently than the younger crabs. However, instances of older crabs going into frequent molting has also been observed.
The question of how long do hermit crabs live also involves the question of diseases. Interestingly, no known disease of hermit crabs has been observed. Hermit crabs are also resistant to any kind of germ infections, but mites inside their shells can be a common problem for the crabs.
The responsibility of the owner is also an important criterion for the life of the little crabs. The care bestowed on hermit crabs is directly proportional to their life span. If not cared properly, a hermit crab dies within a few weeks. On the other hand, if the owner takes great responsibility of the crustacean friend, then they can even live up to 75 years! Generally, hermit crabs live for 25-27 years in their enclosures. Nobody knows how long they live in the wilds. Since, they are adapted to a process of rejuvenation of body tissues, so it is probable that hermit crabs can live for very long periods of time. (Animals with shells usually have very long lifespan; take turtles for instance).
There are a few aspects of hermit crab care that should be mentioned over here. The key points of hermit crab care are maintenance of the crab enclosure, taking proper care during molting, taking proper care of food and water provisions and taking preventive care when you are handling the hermit crabs. The maintenance of the crab enclosure is important for both the marine and the land species. However, it must be mentioned that the maintenance of the marine reef systems is usually more rigorous than maintaining the enclosures of the land crabs. The water in the marine reef aqua system should be without traces of any heavy metals, chemicals and other pollutants. Ammonia, chlorine, nitrite and nitrate concentration of the aquariums should be nil and the specific gravity of the water should be maintained at a range of 1.022-1.0240. The land crab enclosures should be humid enough because the land hermit crabs breathe the oxygen from the humidity in the air.
The provision of nutritious food to the crabs also helps answering the question of how long do hermit crabs live. If the crabs receive nutritious food enriched with calcium, carotenoids and antioxidants then they live healthily and happily for long. The hermit crabs grow in size as they molt and grow. When the crabs are molting seclusion and privacy should be arranged for the land crabs especially. The land crabs generally molt for 8-9 weeks and the marine crabs molt within a couple of minutes. Be careful not to displace or disrupt the unmoving land crab when it is molting because the effects of this can be disastrous. When you are handling the crabs, remember that no traces of soap should be left on your hand, because the ingredients of soap can damage the health of the hermit crabs.
Another important factor that determines how long do hermit crabs live is the presence of a friend. It has been observed that if hermit crabs find their soul mates, they can live for many years.