Rissoides desmaresti is a species

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 mantis shrimp

Mantis shrimp

Mantis shrimp or stomatopods are marine crustaceans, the members of the order Stomatopoda. They are neither shrimp nor mantids, but receive their name purely from the physical resemblance to both the terrestrial praying mantis and the shrimp. They may reach in length, although exceptional cases of...

 native to the eastern 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...

 and 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...

.

Distribution

R. desmaresti is one of only two species of stomatopod found around 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...

, and one of twelve species in the Mediterranean. It is relatively common in the Mediterranean, and is found along the Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an coast as far as the British Isles, although it has not been recorded off the coast of West Africa

West Africa

West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...

. Around Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

, there have been a few observations from 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...

 and North Wales

North Wales

North Wales is the northernmost unofficial region of Wales. It is bordered to the south by the counties of Ceredigion and Powys in Mid Wales and to the east by the counties of Shropshire in the West Midlands and Cheshire in North West England...

, but the only place where significant numbers are known to occur is on a 25 hectares (61.8 acre) site east of Saint Tudwal's Islands

Saint Tudwal's Islands

Saint Tudwal's Islands are a small archipelago lying south of Abersoch on the Llŷn peninsula in North Wales, at the western end of Tremadog Bay...

 in Tremadog Bay

Tremadog Bay

Tremadog Bay is a large inlet of Cardigan Bay, defined by the north Cambrian Coast and the Llŷn peninsula of north Wales.The River Glaslyn flows into the north of bay and St Tudwal's Islands lie at the western end of the bay...

. Its occurrence there may be related to warm currents

Ocean current

An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun...

 coming from the Bay of Biscay

Bay of Biscay

The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...

 and the sheletered nature of the area.

Description

R. desmaresti has a dorso-ventrally flattened body and may reach a size of 70 millimetres (2.8 in). The 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...

 is small and is only fused to the first two segments of the thorax. R. demsaresti is distinguished from the other British species, Platysquilla eusebia

Platysquilla eusebia

Platysquilla eusebia is a species of mantis shrimp in the family Nannosquillidae, from the Mediterranean Sea and north-eastern Atlantic Ocean. It is a spearer, and grows up to long.-Distribution:...

, by the number of spines on the last segment of the raptorial

Raptorial

The term raptorial implies much the same as "predatory", but most often refers to modifications of an arthropod's foreleg that make it function for the grasping of prey while it is consumed, where the gripping surfaces are formed from the opposing faces of two successive leg segments...

 claw; R. desmaresti has five spines, while P. eusebia has a dozen or more. It lives in burrows below from the subtidal zone down to depths of around 40 metres (131.2 ft).

Etymology

The specific epithet "desmaresti" commemorates Anselme Gaëtan Desmarest

Anselme Gaëtan Desmarest

Anselme Gaëtan Desmarest was a French zoologist and author. He was the son of Nicolas Desmarest and father of Anselme Sébastien Léon Desmarest...

, while the generic name Rissoides commemorates Antoine Risso

Antoine Risso

Giuseppe Antonio Risso , called Antoine Risso, was a Niçard naturalist.Risso was born in Nice, County of Nice, a part of the Duchy of Savoy, and studied under Giovanni Battista Balbis. He published , and . Risso's dolphin was named after him...

.