Mictyris longicarpus (Soldier Crab)
Geographic RangeThis particular species is indigenous to eastern Australia. Even though the soldier crab can be found inhabiting certain areas of predominantly eastern Australia, it can be found in other areas as well. The predominant areas stretch between Queensland to New South Wales and again from Victoria to Tasmania.
Food HabitsSoldier crabs usually tend to eat detritus as their main source of food in their intertidal habitats. Therefore these creatures are known as detritavores. Detritus is defined as "Accumulated organic debris from dead organisms, often an important source of nutrients in a food web." (Detritus) Soldier crabs will comb the sandy intertidal zones scooping up this debris with their front claws and eating it. The crabs will then deposit the waste sand that is left over in compacted balls called pseudofaece. When we have a look at the other end of the food chain and/or food web, soldier crabs are the prey of much larger animals such as the heron and the ibis.
ReproductionSoldier crabs reproduce through means of copulation. The female can hold the male's sperm inside her until she releases the eggs. At this time the saved sperm fertilizes the eggs. Females will hold the eggs under her in a sponge-like mass until they are ready to hatch.
BehaviorThis species travels in large numbers of crabs, which have been named "armies". This type of crab is the sole member of its species that is able to walk forwards instead of the typical sideways motion we see in other crabs. When threatened, these soldier crabs begin to burrow themselves into the sandy beaches in a sideways corkscrew-like motion. This motion is mostly in the counterclockwise direction, but some have been seen to burrow in a clockwise direction. This burrowing into the sand increases the oxygenation within the sediments. This is known as bioturbation.
HabitatSoldier Crabs live predominantly on the sandy intertidal shore areas of eastern Australia. These areas have little wave action, but are constantly changing due to tidal activity and other erosion factors. Soldier crabs are typically found near the mangrove communities which provide adequate shelter and some protection for them. The wet and muddy nature of the sands allows for these crabs to make a quick retreat into a newly formed burrow when threatened in any way. Since the areas that these crabs are found in are low energy shorelines, they can become very abundant. Since these crabs can not burrow down into the ground where sea grass in present they tend to have a mutually exclusive relationship with seagrass.
Conservation/BiodiversityAs far as we know, the soldier crab is not an endangered species.
Economic Benefits for Humans
PositiveOne benefit of having Soldier crabs around is that they are scavengers. They feed off of the dead remains of animals on the beach and clean it up.
CommentsThe Soldier crab is a marvel to see with their beautiful lively color and behavior when travelling in their 'armies'. These creatures are a wonder to watch and are a recommended creature to keep an eye out for. That is if they do not burrow their way out of sight first. In the United States of America, our "hermit crab" is also referred to as a "soldier crab". This could cause confusion depending on who you are talking to about soldier crabs. Australians understand the "soldier crab" to be the one shown in the illustration at the beginning of this report.
References and Links
|Reference:||Davie, Peter et al. Wild Guide to Moreton Bay. Queensland Museum. 1998. pp. 101.|
|Entry Author:||Jason Nackley||Hobart College||2002|