''Sphaerechinus granularis'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea urchin Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Toxopneustidae Toxopneustidae is a family of globular sea urchins in the class Echinoidea. Characteristics All Camarodonts have imperforate tubercles and compound ambulacral plates. In addition, the Toxopneustids are characterised by the peristome, or opening t ...

, commonly known as the violet sea urchin, or sometimes the purple sea urchin (though the latter is also a common name for a Pacific sea urchin ''

Strongylocentrotus purpuratus ''Strongylocentrotus purpuratus'' is a species of sea urchin in the family Strongylocentrotidae commonly known as the purple sea urchin. It lives along the eastern edge of the Pacific Ocean extending from Ensenada, Mexico, to British Columbi ...

''). Its range includes the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

and eastern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

Description

''S. granularis'' is a large sea urchin, somewhat flattened dorsally and growing to fifteen centimetres in diameter. There are two distinct colour forms. The

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film) ...

is purple in both but one has purple spines and the other white. The spines are short and blunt, all the same length, and arranged neatly in rows.Picton, B.E. & Morrow, C.C. (2010
''Sphaerechinus granularis'' (Lamarck, 1816)
''Encyclopedia of Marine Life of Britain and Ireland''. Retrieved 2011-08-27. Erizo de mar violáceo (Sphaerechinus granularis), Parque natural de la Arrábida, Portugal, 2021-09-10, DD 57.jpg, White ''Sphaerechinus granularis'' . Sphaerechinus granularis - Tiergarten Schönbrunn.jpg, Dark pink specimen Sphaerechinus granularis MHNT.ZOO.2005.0.239.jpg, Both sides of a dried specimen. - MHNT Erizo de mar violáceo (Sphaerechinus granularis), Parque natural de la Arrábida, Portugal, 2022-07-20, DD 13.jpg, Close up

Distribution and habitat

''S. granularis'' is found in the Mediterranean Sea and the eastern Atlantic Ocean, from the

Channel Islands The Channel Islands are an archipelago in the English Channel, off the French coast of Normandy. They are divided into two Crown Dependencies: the Jersey, Bailiwick of Jersey, which is the largest of the islands; and the Bailiwick of Guernsey, ...

south to

Cape Verde Cape Verde or Cabo Verde, officially the Republic of Cabo Verde, is an island country and archipelagic state of West Africa in the central Atlantic Ocean, consisting of ten volcanic islands with a combined land area of about . These islands ...

and the

Gulf of Guinea The Gulf of Guinea (French language, French: ''Golfe de Guinée''; Spanish language, Spanish: ''Golfo de Guinea''; Portuguese language, Portuguese: ''Golfo da Guiné'') is the northeasternmost part of the tropical Atlantic Ocean from Cape Lopez i ...

. It favours sheltered locations and lives on rocks covered with

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

or gravelly

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

s. It is usually found in the

neritic zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminate ...

down to about , but it is occasionally as . It is also found in meadows of the

seagrass Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...

Posidonia oceanica ''Posidonia oceanica'', commonly known as Neptune grass or Mediterranean tapeweed, is a seagrass species that is endemic to the Mediterranean Sea. It forms large underwater meadows that are an important part of the ecosystem. The fruit is free ...

''.

Biology

''S. granularis'' often covers itself with morsels of algae and shell fragments, which are held in place by the

tube feet Tube or tubes may refer to: * Tube (2003 film), ''Tube'' (2003 film), a 2003 Korean film * "Tubes" (Peter Dale), performer on the Soccer AM#Tubes, Soccer AM television show * Tube (band), a Japanese rock band * Tube & Berger, the alias of dance/e ...

and by the claw-like structures known as

pedicellaria A pedicellaria (: pedicellariae) is a small wrench- or claw-shaped appendage with movable jaws, called valves, commonly found on echinoderms (phylum Echinodermata), particularly in sea stars (class Asteroidea) and sea urchins (class Echinoidea). ...

. It grazes on

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

, especially encrusting

coralline alga Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of re ...

e, seagrass blades and their

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

organisms and

detritus In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

. Spawning takes place at any time of year but the peak period is spring and early summer.

Eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

and

sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...

are liberated into the

water column The (oceanic) water column is a concept used in oceanography to describe the physical (temperature, salinity, light penetration) and chemical ( pH, dissolved oxygen, nutrient salts) characteristics of seawater at different depths for a defined ...

, where egg fertilisation takes place. The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e are

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

ic. After several moults, the echinopluteus larva settles and undergoes

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

before developing into a juvenile.

Ecology

In Tunisia, ''S. granularis'' is found living in association with two other species of sea urchins, '' Centrostephanus longispinus'' and ''

Paracentrotus lividus ''Paracentrotus lividus'' is a species of sea urchin in the family Parechinidae commonly known as the purple sea urchin. It is the type species of the genus and occurs in the Mediterranean Sea and eastern Atlantic Ocean. Description ''Paracentr ...

''. It is preyed upon by the

starfish Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

Marthasterias ''Marthasterias'' is a genus of starfish in the family Asteriidae. Both species in the genus are commonly known as the spiny starfish. Species As of October 2023 the accepted species are: Description ''Marthasterias glacialis'' is a fairly l ...

glacialis'' and ''

Luidia ciliaris ''Luidia ciliaris'', the seven-armed sea star, is a species of sea star (starfish) in the family Luidiidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea. Description ''L. ciliaris'' is an orangeish-brown colour and has s ...

''.

Sphaerechinus granularis three color forms

Use as food

The

gonad A gonad, sex gland, or reproductive gland is a Heterocrine gland, mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gon ...

s of ''S. granularis'' are considered a delicacy in

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

Provence Provence is a geographical region and historical province of southeastern France, which stretches from the left bank of the lower Rhône to the west to the France–Italy border, Italian border to the east; it is bordered by the Mediterrane ...

and

Catalonia Catalonia is an autonomous community of Spain, designated as a ''nationalities and regions of Spain, nationality'' by its Statute of Autonomy of Catalonia of 2006, Statute of Autonomy. Most of its territory (except the Val d'Aran) is situate ...

References

External links

* {{Authority control Toxopneustidae Echinoderms of the Atlantic Ocean Fauna of the Mediterranean Sea Taxa named by Jean-Baptiste Lamarck Echinoderms described in 1816 Sea urchins as food