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Keyhole urchins passively defend themselves. The tough skeleton and spines serve as defense mechanisms. They also burrow under the sand to hide.
Known Predators:
Keyhole urchins are most commonly called sand dollars. They are mostly found washed ashore on beaches and are widely collected by beachcombers and bleach white once they die. Sand dollars have also been used by Christians as a symbol of their beliefs.
Keyhole urchins sense the surrounding environment, light, and temperature by touch through the many sensory cells that are located on the epdermis. These cells are also used to communicate socially.
Communication Channels: chemical
Perception Channels: visual ; tactile ; chemical
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
The life cycles of keyhole urchins are complex and pass through several stages of metamorphosis. After the eggs have been fertilized they will develop into swimming larvae that are bilaterally symmetrical. These swimming larvae are covered with cilia, drift about the sea water as plankton for four to six weeks, and feed on tiny organisms until they metamorphosize into young keyhole urchins that will grow into adults on the ocean floor. The young keyhole urchins eat sand and store it in their gut to weigh them down while developing into adults. Adult keyhole urchins are radially symmetrical. Like all Echinoderms, keyhole urchins are coelomates and deuterostomates.
Development - Life Cycle: metamorphosis
There is no known negative importance for humans.
There is no known positive importance for humans.
Mellita quinquiesperforata have an important role in their ecosystem. Keyhole urchins control the populations of many small organisms. By their mass production of gametes that turn into larvae, they serve as food for the many other organisms within the same ecosystem. They often disturb several layers of sediment by sifting for food and burrowing.
Keyhole urchins are omnivorous and pull food particles from the sand with their tube feet. The food particles are then guided toward the mouth by cilia and mucous. Foods eaten include microorganisms, algae, marine plants and shellfish.
Animal Foods: aquatic crustaceans; other marine invertebrates
Plant Foods: algae; macroalgae
Other Foods: microbes
Primary Diet: omnivore
Mellita quinquiesperforata, or keyhole urchins, are dispersed along the east coast of the United States from Virginia heading south, surrounding the Florida peninsula, west into the Gulf of Mexico to Texas, south to Mexico, and along the coast of Brazil. Keyhole urchins are also found along the coasts of Bermuda, Jamaica, and Puerto Rico.
Biogeographic Regions: atlantic ocean (Native )
Mellita quinquiesperforata is found in shallow waters below tide lines in sandy bottoms. The keyhole urchin favors habitats where the salinity of the water is greater than twenty three parts per thousand. The urchin is most commonly found in bay areas near inlets.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: coastal
Other Habitat Features: intertidal or littoral
The average lifespan of M. quinquiesperforata is four years, but they have been known to survive for up to ten years.
Typical lifespan
Status: wild: 10 (high) years.
Average lifespan
Status: wild: 4 years.
Mellita quinquiesperforata can grow to 140 mm long and 15 cm wide. Smaller keyhole urchins average at 75 mm. Keyhole urchins differ greatly from the closely related sea urchin. Keyhole urchins do not have arms, but have much shorter spines. Their bodies are flattened with an upward slope towards the center of the aboral (top) side, but not perfectly circular in shape. The oral (bottom) surface is usually flat or concave with the mouth directly in the center and the anus to one side. The mouth is made up of five teeth arranged in a circle that form what is called, "Aristotle's lantern". Mellita quinquiesperforata skeletons are called a test and are covered with epidermis, spines used for burrowing, tube feet for locomotion, and cilia. On the aboral side, petalloids, specialized tube feet, are arranged in the shape of five flower petals. The petalloids are used as gills. There are five oval shaped holes, called lunules, that completely pierce the tests of keyhole urchins. There are two pairs of lunules, one pair toward the top and one large longer hole in between the second pair that are towards the bottom. Younger keyhole urchins have notches that will later develop into the lunules. Coloration of M. quinquiesperforata includes tan, brown, and occasionally gray or greenish. Male and female keyhole urchins cannot be distinguished by external characteristics.
Other Physical Features: ectothermic ; heterothermic ; radial symmetry
Mellita quinquiesperforata breed annually from the late spring into the summer months. The success of fertilization is affected by external factors such as temperature, light, salinty, and location of adults.
Keyhole urchins reproduce sexually by external fertilization. Millions of eggs and sperm are released into the water where fertilization occurs. They are also capable of regeneration of spines and areas of their test.
Breeding season: Late spring into the summer months
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External )
There is no parental investment post-spawning.
Parental Investment: pre-fertilization (Provisioning)
In Panama this species has been collected in the Caribbean from Fort Jeferson (USNM E 14584). I have also collected this species in Panama from Bella Vista and Maria Chiquita near Colon and in San Blas, from a depth of 1 to 6 m.
Mortensen, T. (1948). A monograph of the Echinoidea 4(2). Clypeasteroida. Copenhagen. 471 pp., 258 figures, 72 pls; pages: 428-429.
Maluf, L. Y. (1988). Composition and distribution of the central eastern Pacific echinoderms. Natural History Museum of Los Angeles County Technical Reports, 2, 1– 242.
Harold, A. S. & Telford, M. (1990). Systematics, phylogeny and biogeography of the genus Mellita (Echinoidea: Clypeasteroida). Journal of Natural History 24 , 987-1026.
Lessios, H. A. (2005). Echinoids of the Pacific Waters of Panama: Status of knowledge and new records. Rev. Biol. Tropical 53 (sup. 3):147-170.
LSID urn:lsid:marinespecies.org:taxname:158065Clypeaster pentaporus (Gmelin, 1788) (subjective junior synonym)
Echinodiscus quinquiesperforata Leske, 1778 (transferred to Mellita)
Echinus pentaporus Gmelin, 1788 (subjective junior synonym)
Mellita ampla Ravenel, 1848 (subjective junior synonym)
Mellita lata H.L. Clark, 1940 (subjective junior synonym)
Mellita latiambulacra H.L. Clark, 1940 (subjective junior synonym)
Mellita pentapora (Gmelin, 1788) (subjective junior synonym)
Mellita quinquefora (Lamarck, 1816) (subjective junior synonym)
Mellita quinquiesperforata lata H.L. Clark, 1940 (subjective junior synonym)
Mellita quinquiesperforata latiambulacra H.L. Clark, 1940 (subjective junior synonym)
Mellita testudinata L. Agassiz, 1841 (subjective junior synonym)
Mellita testudinata Klein, 1734 (pre-Linean)
Mellita testudinea (incorrect declination of species name)
Scutella pentapora (Gmelin, 1788) (subjective junior synonym)
Scutella quinquefora Lamarck, 1816 (subjective junior synonym)
Mellita quinquiesperforata (Leske, 1778) is a tropical species of sand dollar, a flat, round marine animal related to sea urchins, starfish, and other echinoderms. They can be found along the eastern coast of the United States and the coast of Brazil.[1]
Mellita quinquiesperforata (Leske, 1778) is a tropical species of sand dollar, a flat, round marine animal related to sea urchins, starfish, and other echinoderms. They can be found along the eastern coast of the United States and the coast of Brazil.
Live M. quinquiesperforata (underside)
El dólar de arena (Mellita quinquiesperforata) es una especie de equinodermo de la familia Mellitidae. Recibe este nombre debido a su forma chata y ovalada.[1]
Se caracteriza por presentar un tamaño entre 5 y 10 cm de diámetro, su cuerpo presenta simetría radial y es comprimido dorsal y ventralmente, es decir, es aplanado, en su superficie ventral presenta pequeños túbulos y cilios los cuales utiliza para la locomoción. Su superficie corporal presenta pequeñas espinas. En su superficie dorsal se pueden apreciar estructuras petaloides las cuales son utilizadas como branquias. Presenta en su superficies cinco aberturas o perforaciones ovaladas las cuales se les denomina lúnulas y en razón de dicha característica deriva su nombre específico quinquiesperforata. Por lo general su coloración es de color pardo, gris o verdosa. [2][3][4]
Esta especie presenta una amplia distribución en las costas del océano Atlántico occidental desde las costas de Carolina del Norte en los Estados Unidos hasta las costas de Itapema en Brasil,[4] en la región del mar Caribe[5] se le ha señalado para: Colombia, Costa Rica, Cuba, República Dominicana, Golfo de México, Honduras, Jamaica, El Salvador, Nicaragua, Panamá, Puerto Rico, Aruba, Curazao, Bonaire, Ecuador, costas occidentales de México y Venezuela en este último país habiéndose señalados para los estados Aragua, Carabobo, Miranda, Nueva Esparta, Sucre, Vargas y Falcón.[6][3] Avistado también en las costas tailandesas del mar de Andaman.
Pueden encontrarse en distintos hábitats: en playas con fondo arenoso o rocoso, arrecifes de coral y en lugares costeros tropicales y subtropicales. Como elementos de la infauna suelen alimentarse de animales y plantas microscópicas que se encuentran en los sustratos donde habitan. [3] El registro batimétrico de estos organismos se ubica entre los 0 y 180 metros de profundidad.[4]
Las especies de Mellita se encuentran emparentadas con el género Leodia (M. Isometra y M. tenuis). No tienen órganos reproductores.
El dólar de arena (Mellita quinquiesperforata) es una especie de equinodermo de la familia Mellitidae. Recibe este nombre debido a su forma chata y ovalada.
Les Mellita quinquiesperforata est une espèce d'oursins de l'ordre des Clypéastéroïdes, communément appelé « dollar des sables ».
Ce sont des oursins plats et circulaires, d'où leur surnom anglais de sand dollars, du fait de la ressemblance de leur squelette avec une grosse pièce d'1 $ canadien. Leur forme est arrondie, avec un test (coquille) perforé de cinq ouvertures de forme allongée (qui leur valent l'autre nom de keyhole urchins, ainsi que leur nom scientifique), projetées vers l'arrière. Le corps est recouvert d'un fin duvet de poils, qui sont en fait les radioles (les « piquants » des oursins réguliers), adaptées à la progression dans le sable. Sur la face aborale (supérieure), les cinq « pétales » ambulacraires forment une fleur très visible.
Ces oursins sont très légèrement plus larges que longs, et mesurent jusqu'à 10 cm de diamètre. Le système apical compte 5-6 plaques. La lunule anale est la plus longue[1], et l'anus se situe à son embouchure.
Squelette (test nu), face orale. On distingue la bouche (au centre) et l'anus (en dessous).
On rencontre les Mellita longifissa dans l'Atlantique Ouest, notamment de la Caroline du Nord au Brésil, et dans toutes les Caraïbes[1]. On les trouve de la surface à 130 m de profondeur, mais surtout à moins de 30 m.
Ce sont des oursins fouisseurs, qui vivent enterrés dans le sable ou la vase, qu'ils filtrent pour en retirer les nutriments dont ils se nourrissent.
Cet oursin est apparu dans une publicité américaine pour le dentifrice Colgate (au prix d'un certain nombre d'erreurs scientifiques)[2].
Les Mellita quinquiesperforata est une espèce d'oursins de l'ordre des Clypéastéroïdes, communément appelé « dollar des sables ».
Mellita quinquiesperforata is een zee-egel uit de familie Mellitidae.
De wetenschappelijke naam van de soort werd in 1778 gepubliceerd door Nathanael Gottfried Leske.
Bronnen, noten en/of referenties
Mellita quinquiesperforata (Leske, 1778) é uma espécie de equinoderme, com distribuição natural nas praias das regiões tropicais, conhecido pelo nome comum de bolacha-da-praia devido à sua forma ovalada e achatada.[1]
Mellita quinquiesperforata caracteriza-se por apresentar corpo com simetria radial, comprimido dorso-ventalmente (aplanado) e um diâmetro entre 5 cm e 10 cm. A superficie ventral apresenta pequenos túbulos e cílios utilizados para a locomoção.
A superfície corporal desta espécie apresenta pequenas estruturas em forma de espinho. Na superfície dorsal encontram-se estruturas petaloides utilizadas como brânquias.
O corpo disciforme é perfurado na sua superficies por cinco aberturas ovaladas, denominadas lúnulas. A presença destas perfurações constitui a característica da qual deriva o epíteto específico quiquiesperforata. A espécie apresenta em geral coloração acastanhada, acinzentada ou esverdeada.[2][3][4]
Esta espécie apresenta uma ampla distribuição nas regiões costeiras do Oceano Atlântico ocidental, desde a Carolina do Norte, nos Estados Unidos, até às costas do Rio de Janeiro, no Brasil.[4] Na região do mar das Caraíbas[5] está presente nas costas da Colômbia, Costa Rica, Cuba, República Dominicana, Golfo do México, Honduras, Jamaica, Nicarágua, Panamá, Puerto Rico, Aruba, Curaçao, Bonaire e Venezuela (neste último país presente nos estados de Aragua, Carabobo, Miranda, Nueva Esparta, Sucre e Vargas).[3][6]
A espécie está presente em múltiplos habitats das regiões costeiras, ocorrendo em praias com fundo arenoso ou rochoso e recifes de coral das regiões costeiras tropicais e subtropicais. Como elementos da infauna, alimentam-se de animais e plantas microscópicas que se encuentram nos substratos onde habitam.[3]
O registo batimétrico destes organismos demonstram a sua presença entre os 0 e os 180 metros de profundidade.[4]
As espécies de Mellita são aparentadas com as espécies do género Leodia (M. Isometra e M. tenuis).
Mellita quinquiesperforata (Leske, 1778) é uma espécie de equinoderme, com distribuição natural nas praias das regiões tropicais, conhecido pelo nome comum de bolacha-da-praia devido à sua forma ovalada e achatada.
