Sand Bubbler Crab
Encyclopedia
Sand bubbler crabs are crab
s of the genera
Scopimera and Dotilla in the family Dotillidae
. They are small crabs that live on sandy beaches in the tropical Indo-Pacific; during the low tide, they form inflated sand pellets which are destroyed by the incoming high tide.
, and they are characterised by the presence of "gas windows" on the merus of the legs
; in Dotilla, these windows are also present on the thoracic
sternites. A similar system has evolved in parallel
in the porcelain crab
genus Petrolisthes
.
region, where they occur abundantly on sandy beaches in the tropics and sub-tropics.
Sand bubbler crabs live in burrow
s in the sand, where they remain during high tide. When the tide is out, they emerge on to the surface of the sand, and scour the sand for food, forming it into inflated pellets, which cover the sand. The crabs work radially from the entrance to their burrow, which they re-enter as the tide rises and destroys the pellets. The material consumed by sand bubbler crabs has a very low concentration of organic matter, which is concentrated by egestion of indigestible material.
was Cancer sulcatus (now Dotilla sulcata) by Peter Forsskål
in 1775. The genus Scopimera was originally described as a subgenus
of Ocypode by Wilhem de Haan
in 1833, although the first species, Scopimera globosa was not validly described until 1835. At the same time, De Haan tried to erect the genus Doto for Forskål's Cancer sulcatus, not realising that the name was preoccupied by the mollusc genus Doto. The first available name for that genus was published by William Stimpson
in 1858, who called it Dotilla. Ongoing revisions are likely to split the current genus Scopimera into at least two genera.
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s of the genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Scopimera and Dotilla in the family Dotillidae
Dotillidae
Dotillidae is a family of crabs. It comprises 59 species, nearly half of which are in the genus Ilyoplax. The two genera Scopimera and Dotilla are collectively the sand bubbler crabs, which leave conspicuous collections of sand pellets on sandy beaches across the tropical and sub-tropical...
. They are small crabs that live on sandy beaches in the tropical Indo-Pacific; during the low tide, they form inflated sand pellets which are destroyed by the incoming high tide.
Description
Sand bubbler crabs are small crabs, around 1 cm (0.393700787401575 in) across the carapaceCarapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
, and they are characterised by the presence of "gas windows" on the merus of the legs
Arthropod leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...
; in Dotilla, these windows are also present on the thoracic
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
sternites. A similar system has evolved in parallel
Parallel evolution
Parallel evolution is the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.-Parallel vs...
in the porcelain crab
Porcelain crab
Porcelain crabs are decapod crustaceans in the widespread family Porcellanidae, which superficially resemble true crabs. They are typically less than wide, and have flattened bodies as an adaptation for living in rock crevices...
genus Petrolisthes
Petrolisthes
Petrolisthes is a genus of marine porcelain crabs, containing the following extant species:*Petrolisthes aegyptiacus Werding & Hiller, 2007*Petrolisthes agassizii Faxon, 1893*Petrolisthes amoenus...
.
Distribution
Sand bubbler crabs are widespread across the Indo-PacificIndo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
region, where they occur abundantly on sandy beaches in the tropics and sub-tropics.
Ecology and behaviour
Burrow
A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...
s in the sand, where they remain during high tide. When the tide is out, they emerge on to the surface of the sand, and scour the sand for food, forming it into inflated pellets, which cover the sand. The crabs work radially from the entrance to their burrow, which they re-enter as the tide rises and destroys the pellets. The material consumed by sand bubbler crabs has a very low concentration of organic matter, which is concentrated by egestion of indigestible material.
Taxonomic history
The first sand bubbler crab to be describedAlpha taxonomy
Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...
was Cancer sulcatus (now Dotilla sulcata) by Peter Forsskål
Peter Forsskål
Peter Forsskål, sometimes spelled Pehr Forsskål, Peter Forskaol, Petrus Forskål or Pehr Forsskåhl, was a Swedish explorer, orientalist, naturalist and an apostle of Carl Linnaeus.-Early life:...
in 1775. The genus Scopimera was originally described as a subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
of Ocypode by Wilhem de Haan
Wilhem de Haan
Wilhem de Haan was a Dutch zoologist. He specialised in the study of insects and crustaceans, and was the first keeper of invertebrates at the Rijksmuseum in Leiden, now Naturalis. He was forced to retire in 1846, when he was partially paralysed by a spinal disease...
in 1833, although the first species, Scopimera globosa was not validly described until 1835. At the same time, De Haan tried to erect the genus Doto for Forskål's Cancer sulcatus, not realising that the name was preoccupied by the mollusc genus Doto. The first available name for that genus was published by William Stimpson
William Stimpson
William Stimpson was a noted American scientist.- Biography :Stimpson was born in Boston, Massachusetts to Herbert Hathorne Stimpson and Mary Ann Devereau Brewer. The Stimpsons were of the old colonial and Revolutionary stock of Massachusetts, the earliest known member of the family being James...
in 1858, who called it Dotilla. Ongoing revisions are likely to split the current genus Scopimera into at least two genera.
Species
Eight species of Dotilla and fifteen of Scopimera are currently recognised:- Dotilla blanfordi Alcock, 1900
- Dotilla fenestrata Hilgendorf, 1869
- Dotilla intermedia De Man, 1888
- Dotilla malabarica Nobili, 1903
- Dotilla myctiroides (H. Milne-Edwards, 1852)
- Dotilla pertinax Kemp, 1915
- Dotilla sulcata (Forskål, 1775)
- Dotilla wichmani De Man, 1892
- Scopimera bitympana Shen, 1930
- Scopimera crabicauda Alcock, 1900
- Scopimera curtelsoma Shen, 1936
- Scopimera globosa (De Haan, 1835)
- Scopimera gordonae Serène & Moosa, 1981
- Scopimera inflata A. Milne-Edwards, 1873
- Scopimera intermedia Balss, 1934
- Scopimera investigatoris Alcock, 1900
- Scopimera kochi Roux, 1917
- Scopimera longidactyla Shen, 1932
- Scopimera philippinensis Wong, Shih & Chan, 2011
- Scopimera pilula Kemp, 1919
- Scopimera proxima Kemp, 1919
- Scopimera sheni Wong, Shih & Chan, 2011
- Scopimera sigillorum (Rathbun, 1914)