Gecarcinidae

A land crab ( Gecarcinus quadratus ) from Panama

The land crabs ( Gecarcinidae ) living with about 20 species in tropical coastal regions. They are exclusive land animals that seek the ocean only to lay their eggs and their larvae develop in the sea. The gill cavity of the land crabs is powered by a thin-skinned water bag with moisture and has taken over the function of a spare lung.

The land crabs include the Christmas Island crab ( Gecarcoidea natalis ) on the Australian Christmas Island, the Central American Halloween Crab ( Gecarcinus ruricola ), the West African Harlequin crab ( Cardisoma armatum ), which lives in coastal palm forests and the spread from Florida to Brazil Cardisoma guanhumi ( they walk up to 8 miles from the sea). Land crabs live during the day in caves under mangroves or in deep, self-dug holes, ranging in some species up to the groundwater. They eat carrion and preferably plants and seek their food mainly at night or at dusk.

Reproduction

The copulation of the land crabs takes place on land. Only the females migrate to the sea to deposit the hatching larvae. They live a few weeks in the sea and migrate to their metamorphosis ashore. In the first period they keep well hidden only on particularly wet places, since the gills have to adapt only.

Ecology

Due to their diet and lifestyle, the land crabs occupy an important position in the ecosystem of the islands and coastline that inhabit it. By digging of burrows they loosen the soil and speed, similarly to other regions of the earthworms, through their plant-based diet the leaves decay. As scavengers, they reduce the spread of vermin. On small islands, land crabs at the top of the food pyramid can act as top predators (see also: Clipperton Island ).

An in nature so far unique hydrostatic skeleton of gas and water, the land crab Gecarcinus lateralis in the phase after a molt on: After shedding of the old tank, the animals inflate using compressed gas in their intestines on. In this way, the body of the crab, also known as Halloween animal receives the necessary stability to her - under the old tank indeed already fully formed, but still soft - new tank is sufficiently cured.

System

The land crabs are probably not a monophyletic group. Accordingly, some changes in the scheme are still to be expected. Currently, the land crabs are divided into four to six genera. Michael Türkay from the Senckenberg Research Institute announced 1970 Gecarcinus genus into two subgenera, giving priority to the subgenus Gecarcinus ( Johngarthia ) the three species C. planatus ( Stimpson, 1860), C. malpilensis ( Faxon 1893) and C. lagostoma (H. Milne Edwards, 1837) zuwies. 1973 ostatlantisch in the Gulf of Guinea widespread subgroup of C. lagostoma as a separate species C. weileri ( Sendler, 1912) was separated from the western Atlantic subgroup. 1987 brought the Türkay furnished by him a subgenus of its own genus under the name Johngarthia, in honor of zoologist and crab researcher John Garth. The genus Discoplax was introduced by Alphonse Milne -Edwards in 1867 for the long-legged land crab Discoplax longipes. Michael Türkay introduced in 1987 two species of the genus Cardisoma, namely Cardisoma rotunda and Cardisoma also hirtipes to the genus Discoplax. 2001 another species of this genus was described by Peter Ng and Guinot Daniéle, namely gracilipes Discoplax.

• Gecarcinidae, land crabs Cardisoma Cardisoma armatum, harlequin shrimp
• Cardisoma guanhumi, West Atlantic land crab
• Cardisoma carnifex, Purple land crab
• Cardisoma crassum

• Discoplax hirtipes, Blue Crab
• Discoplax longipes, Leggy land crab
• Discoplax rotunda
• Discoplax gracilipes

• Epigrapsus notatus
• Epigrapsus politus

• Gecarcinus lateralis, Halloween Crab ( Red Land Crab )
• Gecarcinus quadratus, Halloween Crab
• Gecarcinus ruricola, Halloween Crab ( Purple land crab )

• Gecarcoidea natalis, Christmas Island Crab
• Gecarcoidea lalandii,

• Johngarthia lagostoma
• Johngarthia malpilensis
• Johngarthia planatus (often on Clipperton )
• Johngarthia weileri