Pachygrapsus marmoratus
Encyclopedia
Pachygrapsus marmoratus is a species
of crab
, sometimes called the marbled rock crab or marbled crab, which lives in the Black Sea
, the Mediterranean Sea
and parts of the Atlantic Ocean
. It is dark violet brown, with yellow marbling
, and with a body up to 36 millimetres (1.4 in) long. It is an omnivore
, feeding on algae
and various animals including mussel
s and limpet
s.
22–36 mm (0.866141732283465–1.4 ) long, which is dark violet brown with marbling
in yellow. It can be distinguished from related species of Pachygrapsus
in the Mediterranean Sea
(Pachygrapsus maurus and Pachygrapsus transversus) by the presence of three teeth on each side of the carapace. It is capable of very rapid movements, and it uses this ability to dart into crevices, making it difficult to catch.
, from the Black Sea
to the Moroccan
coast, and along the Atlantic
coasts of Portugal
, Spain
and France
, and was observed as early as 1996 as far north as Southampton
in the English Channel
. This range expansion may be due to the warming
of the surface waters.
, but not an opportunist; crabs consume similar proportions of algae
and animal
s however abundant they are in the crab's habitat. The favoured animals in the diet of P. marmoratus are mussel
s, limpet
s and its own species. When attacking the limpet Patella depressa
, P. marmoratus uses a consistent method, which is usually unsuccessful. On more sheltered shores, P. grapsus eats fewer mussel
s, but compensates with a greater consumption of barnacle
s.
Predators of Pachygrapsus marmoratus include the musky octopus, Eledone moschata
.
The larva
e of P. marmoratus are plankton
ic and may survive for up to 31 days. This results in high levels of gene flow
between populations, and allows the species to rapidly colonise new areas.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of crab
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...
, sometimes called the marbled rock crab or marbled crab, which lives in the Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
, the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
and parts of the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
. It is dark violet brown, with yellow marbling
Marbling
Marbling may refer to:*The quality of a surface that has streaks of color, like marble. For example:**Marbleizing, also called faux marbling, the art of painting walls or furniture to look like real marble....
, and with a body up to 36 millimetres (1.4 in) long. It is an omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
, feeding on algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
and various animals including mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s and limpet
Limpet
Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...
s.
Description
P. marmoratus has a square 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...
22–36 mm (0.866141732283465–1.4 ) long, which is dark violet brown with marbling
Marbling
Marbling may refer to:*The quality of a surface that has streaks of color, like marble. For example:**Marbleizing, also called faux marbling, the art of painting walls or furniture to look like real marble....
in yellow. It can be distinguished from related species of Pachygrapsus
Pachygrapsus
Pachygrapsus is a genus of small shore crabs comprising the following species:*Pachygrapsus corrugatus *Pachygrapsus crassipes Randall, 1840*Pachygrapsus fakaravensis Rathbun, 1907...
in the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
(Pachygrapsus maurus and Pachygrapsus transversus) by the presence of three teeth on each side of the carapace. It is capable of very rapid movements, and it uses this ability to dart into crevices, making it difficult to catch.
Distribution
It is widespread in Southern EuropeSouthern Europe
The term Southern Europe, at its most general definition, is used to mean "all countries in the south of Europe". However, the concept, at different times, has had different meanings, providing additional political, linguistic and cultural context to the definition in addition to the typical...
, from the Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
to the Moroccan
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
coast, and along the Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
coasts of Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, and was observed as early as 1996 as far north as Southampton
Southampton
Southampton is the largest city in the county of Hampshire on the south coast of England, and is situated south-west of London and north-west of Portsmouth. Southampton is a major port and the closest city to the New Forest...
in the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...
. This range expansion may be due to the warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
of the surface waters.
Ecology
P. marmoratus is an omnivoreOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
, but not an opportunist; crabs consume similar proportions of algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
and animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s however abundant they are in the crab's habitat. The favoured animals in the diet of P. marmoratus are mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s, limpet
Limpet
Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...
s and its own species. When attacking the limpet Patella depressa
Patella depressa
Patella depressa is a species of sea snail, a true limpet, a marine gastropod mollusk in the family Patellidae, one of the families of true limpets....
, P. marmoratus uses a consistent method, which is usually unsuccessful. On more sheltered shores, P. grapsus eats fewer mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s, but compensates with a greater consumption of barnacle
Barnacle
A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...
s.
Predators of Pachygrapsus marmoratus include the musky octopus, Eledone moschata
Eledone moschata
Eledone moschata, the musky octopus, is a species of octopus that lives in the Mediterranean Sea. It grows up to long, and feeds on a wide range of crustaceans, molluscs and fish.-Distribution:...
.
The larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of P. marmoratus are plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic and may survive for up to 31 days. This results in high levels of gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
between populations, and allows the species to rapidly colonise new areas.