Keyhole sand dollar (Mellita quinquiesperforata)
Source-cited species reference: taxonomy from WoRMS, biology from SeaLifeBase, occurrence map from GBIF, description from Wikipedia.
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The original uploader was Gerhard H at English Wikipedia. · via Wikipedia: Mellita quinquiesperforata · CC BY-SA 3.0
Mellita quinquiesperforata is a tropical species of sand dollar, a flat, round marine animal related to sea urchins, starfish, and other echinoderms. They have been found to possess significantly more food in the gut at night than in the day. This species can be found along the eastern coast of the United States and the coast of Brazil. Inverted sand dollars are able to recognize flow direction and respond by modifying their orientation to maximize lift and drag for righting their position.
Scientific classification
- KingdomAnimalia
- PhylumEchinodermata
- ClassEchinoidea
- OrderClypeasteroida
- FamilyMellitidae
- GenusMellita
- SpeciesMellita quinquiesperforata
Named by (Leske, 1778)
Sources: Wikipedia taxobox: Mellita quinquiesperforata (CC BY-SA 4.0) · differs from this box at order: WoRMS AphiaID 158065 (CC BY 4.0)
Where the keyhole sand dollar (mellita quinquiesperforata) has been recorded
Each dot is a place where the species has been observed and reported (1,867 records, half-degree grid) — not a modelled range. 119 inland records left out (institution coordinates).
Map: drawn by Codexery. Data: GBIF occurrence search (records CC0 / CC BY) · Natural Earth basemap (public domain)
Classification (WoRMS)
Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Echinodermata · Class: Echinoidea · Order: Echinolampadacea · Family: Mellitidae · Genus: Mellita.
Accepted name: Mellita quinquiesperforata · Authority: (Leske, 1778) · Taxonomic status: accepted · AphiaID: 158065.
Synonyms and superseded combinations recorded for this taxon: Clypeaster pentaporus (Gmelin, 1791); Echinodiscus quinquies perforatus Leske, 1778; Echinodiscus quinquiesperforata Leske, 1778; Echinus pentaporus Gmelin, 1791; Mellita ampla Ravenel, 1848; Mellita lata H.L. Clark, 1940; Mellita latiambulacra H.L. Clark, 1940; Mellita pentapora (Gmelin, 1791); Mellita quinquefora (Lamarck, 1816); Mellita quinquiesperforata lata H.L. Clark, 1940; Mellita quinquiesperforata latiambulacra H.L. Clark, 1940; Mellita testudinata L. Agassiz, 1841; Mellita testudinata Klein, 1734; Mellita testudinea; Scutella pentapora (Gmelin, 1791); Scutella quinquefora Lamarck, 1816.
Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=158065 (CC BY 4.0). Accessed 2026-09-25.
Biology and life history (SeaLifeBase)
Measured values published by SeaLifeBase for Mellita quinquiesperforata. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.
Depth range: 1–180 m · Habitat zone: benthic.
SeaLifeBase notes: This is an epibenthic species found on soft bottom substrates in sublittoral areas (Ref. 83942). Also on shell hash (Ref. 111335).
Source: SeaLifeBase species summary (SpecCode 49346) — https://www.sealifebase.se/summary/Mellita-quinquiesperforata.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.
Distribution and occurrence records (GBIF)
1,867 georeferenced occurrence records for Mellita quinquiesperforata are published through GBIF from 27 countries or marine areas. The map above plots 139 distinct locations from a sample of 1,867 records, omitting 147 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.
Most records by country or area: United States of America (891); Brazil (491); Mexico (201); Panama (83); Puerto Rico (43).
The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.
Source: GBIF Occurrence Search (taxonKey 2279048) — https://www.gbif.org/occurrence/search?taxon_key=2279048&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=158065 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-25.
Description and natural history (Wikipedia)
The five-holed keyhole urchin, also known as the sand dollar, resides in the Atlantic Ocean off the Eastern coast of North, Central, and South America. They can be found anywhere near the coast of South Carolina, from Hilton Head to Myrtle Beach. Their dried exoskeletons are a common sight on sandy beaches, often in the high tide zone.
The five-holed keyhole urchin prefers fine-grained sand in the infralittoral zone, which is shallow and dominated by marine algae. To keep from being tossed around by the current, they form extensive beds parallel to the shoreline, just beyond the breaker zone. Studies show that bed structure and density are associated with the dynamic nature of tidal zones and can vary from beach to beach. Spatial dispersion within a bed, as well as individual growth rate, has also been correlated with water depth.
Like starfish, the keyhole urchin possesses tube feet and cilia for locomotion and spines for burrowing into the sand. Their skeletons, called tests, are made of calcium carbonate. This echinoderm uses its numerous tube feet to pick up food items, including copepods, algae, seaweed, and small shellfish. Then, its cilia help move the food to its mouth, which is in the center of its body.
Source: Wikipedia: Mellita quinquiesperforata — https://en.wikipedia.org/wiki/Mellita_quinquiesperforata (CC BY-SA 4.0). Accessed 2026-09-25.
Related in Keyhole sand dollar
Links follow this subject's own source article.
Elsewhere in Keyhole sand dollar
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Mellita quinquiesperforata (CC BY-SA 4.0).
- Classification: the source article's taxobox; compare WoRMS, the World Register of Marine Species (CC BY 4.0).
- Occurrence records: GBIF (CC0 / CC BY). Basemap: Natural Earth (public domain).
- Biology values: SeaLifeBase species summary (CC BY-NC 3.0, non-commercial).
- Word definitions: the , each quoted from its Wikipedia article.
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