The first time I came across a Haswell’s Shore Crab was during a “Clean Up Australia Day” at a reserve area in Hays Inlet which included mangrove and saltmarsh habitats. There was a number of car wrecks in the wetland area (which were all removed at a later date by the local Council) as well as domestic debris including a large piece of carpet overlay which was almost welded to the ground surface. As we pulled up the offending piece of carpet we were surprised by a number of brown and orange crabs who immediately lifted their claws and let us know their displeasure!
Since then, and many clean up days later, I have always rushed to any piece of flat rubbish or debris in order to look for these marvelous creatures. They are one of the dominant species in the saltmarsh habitat which can prove to be a tough area to make a living in. Over the years we have seen the salinity in these habitats vary greatly from below ocean levels (approximately 35 parts of salt per thousand) to more than triple the salinity. During extended dry periods, the saltmarsh soil dries out, cracks and is often covered with a salt encrustation. There is no shade, except from the saltmarsh succulents and the marine couch so it can get very hot as well.
The crabs are pretty hardy and dig burrows in the marine couch area in order to escape the sun and avoid desiccation. They are generally nocturnal feeders which makes sense in terms of avoiding the harsh conditions as well as reducing the risk of predation. With a number of wetland birds scouring the area during daylight hours it is a good strategy to avoid becoming an avian meal. Of course another idea is to find a piece of debris such as carpet and make their way underneath in order to take advantage of a moist retreat from the harsh conditions of the saltmarsh.
They are very common in the saltmarsh areas, and often you will see hundreds of their casts dispersed across the saltmarsh vegetation almost like snow.
Since then, and many clean up days later, I have always rushed to any piece of flat rubbish or debris in order to look for these marvelous creatures. They are one of the dominant species in the saltmarsh habitat which can prove to be a tough area to make a living in. Over the years we have seen the salinity in these habitats vary greatly from below ocean levels (approximately 35 parts of salt per thousand) to more than triple the salinity. During extended dry periods, the saltmarsh soil dries out, cracks and is often covered with a salt encrustation. There is no shade, except from the saltmarsh succulents and the marine couch so it can get very hot as well.
The crabs are pretty hardy and dig burrows in the marine couch area in order to escape the sun and avoid desiccation. They are generally nocturnal feeders which makes sense in terms of avoiding the harsh conditions as well as reducing the risk of predation. With a number of wetland birds scouring the area during daylight hours it is a good strategy to avoid becoming an avian meal. Of course another idea is to find a piece of debris such as carpet and make their way underneath in order to take advantage of a moist retreat from the harsh conditions of the saltmarsh.
They are very common in the saltmarsh areas, and often you will see hundreds of their casts dispersed across the saltmarsh vegetation almost like snow.
RSS Feed
