Xantho hydrophilus
Encyclopedia
Xantho hydrophilus is a species
of crab
. It is yellowish-brown and grows to a carapace
width of 70 mm (2.8 in). It is a nocturnal herbivore
that lives in shallow marine waters from western Scotland
to the Cape Verde
Islands.
of Xantho hydrophilus reaches a width of 70 millimetres (2.8 in), and a length of up to 22 mm (0.866141732283465 in). The antero-lateral edge of the carapace bears five blunt lobes. It is yellowish-brown, except for the tips of the chelae, which are black. X. hydrophilus closely resembles X. pilipes, from which it can be distinguished by the absence of fringes of seta
e on the second to fifth pairs of pereiopods (walking legs).
, up to a depth of 40 metres (131.2 ft). It is a herbivore
which feeds chiefly on various algae
, and is mostly active at night.
Mating takes place in spring, and the females carry the fertilised egg
s on their pleopods from March to July; the larvae
can be found in the plankton
over most of the summer.
, the Cape Verde
Islands, the Azores
and the Canary Islands
in the south, north to the western and southern coasts of the British Isles
, reaching its northern limit in western Scotland
. The populations in the Mediterranean Sea have been recognised as a separate taxon, initially as the subspecies Xantho hydrophilus granulimanus, but now generally as the species Xantho granulimanus.
in 1790, under the name Cancer hydrophilus. It was later described under the name Cancer floridus by George Montagu (1808) and under the name Cancer incisus by William Elford Leach
(1814). Confusingly, it has also been referred to by names of other taxa, such as Xantho poressa
and Xantho pilipes.
A crab species from the Indo-Pacific
was described in 1834 as "Xantho incisus" by Henri Milne-Edwards
; that species is now known as Lophozozymus incisus.
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...
. It is yellowish-brown and grows to a carapace
Carapace
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...
width of 70 mm (2.8 in). It is a nocturnal herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
that lives in shallow marine waters from western Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
to the Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
Islands.
Description
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...
of Xantho hydrophilus reaches a width of 70 millimetres (2.8 in), and a length of up to 22 mm (0.866141732283465 in). The antero-lateral edge of the carapace bears five blunt lobes. It is yellowish-brown, except for the tips of the chelae, which are black. X. hydrophilus closely resembles X. pilipes, from which it can be distinguished by the absence of fringes of seta
Seta
Seta is a biological term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms.-Animal setae:In zoology, most "setae" occur in invertebrates....
e on the second to fifth pairs of pereiopods (walking legs).
Ecology
Xantho hydrophilus lives under stones on sandy and stony beaches, below the intertidal zoneIntertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
, up to a depth of 40 metres (131.2 ft). It is a herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
which feeds chiefly on various 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 is mostly active at night.
Mating takes place in spring, and the females carry the fertilised egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s on their pleopods from March to July; the larvae
Crustacean larvae
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow...
can be found in the 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...
over most of the summer.
Distribution
Xantho hydrophilus is found from the Mediterranean SeaMediterranean 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...
, the Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
Islands, the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
and the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
in the south, north to the western and southern coasts of the British Isles
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
, reaching its northern limit in western Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
. The populations in the Mediterranean Sea have been recognised as a separate taxon, initially as the subspecies Xantho hydrophilus granulimanus, but now generally as the species Xantho granulimanus.
Nomenclature
Xantho hydrophilus was first described by Johann Friedrich Wilhelm HerbstJohann Friedrich Wilhelm Herbst
Johann Friedrich Wilhelm Herbst was a German naturalist and entomologist from Petershagen, Minden-Ravensberg....
in 1790, under the name Cancer hydrophilus. It was later described under the name Cancer floridus by George Montagu (1808) and under the name Cancer incisus by William Elford Leach
William Elford Leach
William Elford Leach FRS was an English zoologist and marine biologist.Leach was born at Hoe Gate, Plymouth, the son of a solicitor. At the age of twelve he went to school in Exeter, studying anatomy and chemistry. By this time he was already collecting marine samples from Plymouth Sound and along...
(1814). Confusingly, it has also been referred to by names of other taxa, such as Xantho poressa
Xantho poressa
Xantho poressa is a species of crab from the Black Sea, Mediterranean Sea and parts of the eastern Atlantic Ocean. It is one of four species in the genus Xantho....
and Xantho pilipes.
A crab species from the Indo-Pacific
Indo-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...
was described in 1834 as "Xantho incisus" by Henri Milne-Edwards
Henri Milne-Edwards
Henri Milne-Edwards was an eminent French zoologist.Henri Milne-Edwards was the 27th child of William Edwards, an English planter and militia colonel in Jamaica and Elisabeth Vaux, a French. He was born in Bruges, Belgium, where his parents had retired. At that time, Bruges was a part of the...
; that species is now known as Lophozozymus incisus.