Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater and fresh water together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root brak. Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it can be damaging to the environment.
Mangrove crabs are crabs that live in and around mangroves. They belong to many different species and families and have been shown to be ecologically significant by burying and consuming leaf litter. Mangrove crabs have a variety of phylogenies because mangrove crab is an umbrella term that encompasses many species of crabs. Two of the most common families are sesarmid and fiddler crabs. They are omnivorous and are predated on by a variety of mammals and fish. They are distributed widely throughout the globe on coasts where mangroves are located. Mangrove crabs have wide variety of ecological and biogeochemical impacts due to the biofilms that live in symbiosis with them as well as their burrowing habits. Like many other crustaceans, they are also a human food source and have been impacted by humans as well as climate change.
The Dungeness crab makes up one of the most important seafood industries along the west coast of North America. Its typical range extends from Alaska's Aleutian Islands to Point Conception, near Santa Barbara, California. Dungeness typically grow 6–7 in (150–180 mm) at their widest point and inhabit eelgrass beds and sandy bottoms. Its common name comes from the Dungeness Spit in the Strait of Juan de Fuca, Washington state, United States, which shelters a shallow bay inhabited by the crabs.
The Chinese mitten crab, also known as the Shanghai hairy crab, is a medium-sized burrowing crab that is named for its furry claws, which resemble mittens. It is native to rivers, estuaries and other coastal habitats of East Asia from Korea in the north to Fujian, China in the south. It has also been introduced to Europe and North America, where it is considered an invasive species. The species features on the list of invasive alien species of Union concern. This means that the import of the species and trade in the species is forbidden in the whole of the European Union.
The Diogenidae are a family of hermit crabs, sometimes known as "left-handed hermit crabs" because in contrast to most other hermit crabs, its left chela (claw) is enlarged instead of the right. It comprises 429 extant species, and a further 46 extinct species, making it the second-largest family of marine hermit crabs, after the Paguridae.
Adenium obesum, more commonly known as a desert rose, is a poisonous species of flowering plant belonging to the tribe Nerieae of the subfamily Apocynoideae of the dogbane family, Apocynaceae. It is native to the Sahel regions south of the Sahara, tropical and subtropical eastern and southern Africa, as well as the Arabian Peninsula. Other names for the flower include Sabi star, kudu, mock azalea, and impala lily. Adenium obesum is a popular houseplant and bonsai in temperate regions.
The Majoidea are a superfamily of crabs which includes the various spider crabs.
Sesarma reticulatum, the purple marsh crab or simply marsh crab, is a crab species native to the salt marshes of the eastern United States.
The Sesarmidae are a family of crabs, previously included in the Grapsidae by many authors. Several species, namely in Geosesarma, Metopaulias, and Sesarma, are true terrestrial crabs. They do not need to return to the sea even for breeding.
The purple shore crab is a common crab of the family Varunidae that is indigenous to the west coast of United States, Canada, and Mexico. H. nudus was first described in 1847 by Adam White, and in 1851, James Dwight Dana formally classified the species. H. nudus is a small, amphibious crab that is similar physically and behaviorally to Pachygrapsus crassipes and Hemigrapsus oregonensis. The purple shore crab is generally a dark purple color with olive green, red, and white spots. Mating season for H. nudus begins in mid-winter and larval crabs undergo 5 zoeal stages and a juvenile stage. Adult crabs mainly feed on algae but will occasionally scavenge other animals. H. nudus prefers inter-tidal and sub-tidal zones, and it can oftentimes be found sheltering under rocks or other debris. H. nudus demonstrates complex compensatory mechanisms to counteract fluctuating salinity and water oxygen concentrations, permitting it to live in a variety of different environments.
Hemigrapsus oregonensis is a small shore crab of the family Varunidae; formerly classified under the family Grapsidae. It is known under several common names, including yellow shore crab, hairy shore crab, green shore crab, mud-flat crab, bay shore crab and Oregon shore crab. Despite its common name, the crab actually has a wide variety of coloration. It is found along the West Coast of the United States and Canada, specifically along shorelines and similar geographical areas. In 2009, H. oregonensis was included on a list of animals petitioning for the endangered species label, but there was not enough scientific information available for it to be considered as such, so it remains unevaluated to the present day.
Heloecius cordiformis is a species of semiterrestrial crab found in mangrove swamps and mudflats along the east coast of Australia. Adults are around 25 mm (1 in) wide, with males being larger and having larger and more conspicuously coloured claws. The males wave their claws to communicate with other crabs, giving them their common name of semaphore crab. They can breathe both in air and under water, and feed at low tide on detritus in the sediment. H. cordiformis is the only species in the genus Heloecius and the family Heloeciidae.
A number of lineages of crabs have evolved to live predominantly on land. Examples of terrestrial crabs are found in the families Gecarcinidae and Gecarcinucidae, as well as in selected genera from other families, such as Sesarma, although the term "land crab" is often used to mean solely the family Gecarcinidae.
Around 65 species of crab occur in the waters of the British Isles. All are marine, with the exception of the introduced Chinese mitten crab, Eriocheir sinensis, which occurs in fresh and brackish water. They range in size from the deep-water species Paromola cuvieri, which can reach a claw span of 1.2 metres, to the pea crab, which is only 4 mm (0.16 in) wide and lives inside mussel shells.
Oregonia bifurca, commonly known as the split-nose crab or the split-nose decorator crab, is a species of crabs belonging to the family Oregoniidae. It is a rare deep-water species that inhabits the tops of seamounts and guyots in the northeastern Pacific Ocean; from the Aleutian Islands, the Bering Sea, the Hawaiian–Emperor seamount chain, to the waters off British Columbia. It is closely related to the more common shallow-water species Oregonia gracilis, the graceful decorator crab.
Geosesarma dennerle is a species of small land-living crabs found on Java, Indonesia.
Armases cinereum, also known as the squareback marsh crab or wharf crab, is a species of crab in the family Sesarmidae. The wharf crab is a small crab that is dark brown to muddy in color, which allows it to blend in with its usual surroundings. It is found on the Atlantic southeastern coast, down into the Gulf of Mexico. It is an omnivore and is prevalent in marshy coastal environments along the Southwestern Atlantic.
Metasesarma is a genus of crabs in the family Sesarmidae.
Davusia glabra, commonly called the shiny bait crab, Sowrie crab or Sourie crab is the sole species of crab in the genus Davusia. It lives around the low tide area on rocky ocean shores on the eastern coast of Australia, in crevices and rock pools and on rock platforms. Its distribution is stated differently in different sources; some have described the crab's habitat as from Queensland to as far south as the NSW-Victorian border, while others have stated it can be found as far south as Wilson's Promontory. Its carapace is grey to fawn-colored with very small green spots, resulting in Davusia glabra having a greenish appearance. The width of the carapace is around 30-40 mm across and is smooth without hair, slightly wider than long, with 3 distinct spines at each edge.
Parasesarma messa, commonly known as the maroon mangrove crab, is a species of burrowing crab found in Queensland, Australia. It lives in mangroves in estuaries and sheltered bays. It was originally described as Sesarma messa, but was placed in the genus Parasesarma in 2017. Perisesarma messa is also a synonym.
