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Sea urchins of the Gulf of California facts for kids

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California Purple Sea Urchin
Echinometra vanbrunti, at low tide in Puerto Peñasco, Sonora, Mexico

The sea urchins of the Gulf of California live between the coasts of the Baja California Peninsula to the west and mainland state of Sonora, Mexico to the east. The northern boundary is the lateral band of land with the remains of the Colorado River Delta, and the southern is the Pacific Ocean.

The Gulf of California is known for its high diversity and endemism of biota. One type of marine animal that can be found in this region is the sea urchin (class echinoidea, in the phylum echinodermata). One echinoid, Mellita granti, is a sea urchin endemic to the Gulf of California.


Approximately 23 species of sea urchins, 3 species of heart urchins, and 9 species of sand dollars call the Gulf of California habitat their home. Where they are found throughout the Gulf of California, can be classified into three biogeographic regions called the Northern Gulf, Central Gulf, and Southern Gulf.

Two other regions are also used to classify sea urchins and other marine animals, and are called the Southwest Baja California Sur Region and the Colorado River Delta Biosphere Reserve.

The biogeographic regions of the Gulf of California

Slate Pencil Urchin
Eucidaris thouarsii among the rocks in Puerto Peñasco, Mexico
  • Northern Gulf (GNC) – extends from the Colorado River Delta south to Baja California and Sonora, and includes the Midriff Islands (Tiburón Island - Isla Ángel de la Guarda).
  • Central Gulf (GCC) – extends from the GNC’s southern border (the Midriff Islands) to Sonora and Baja California Sur (Punta Coyote).
  • Southern Gulf (GCS) – extends from the southern border of GCC to Cabo Coririanteds in Jalisco to Cabo San Lucas on the Baja California Peninsula in Baja California Sur.
  • Southwest Baja California Sur Region (SBC) – extends along the western coast of Baja California from Cabo Talso to Bahia Magdelena lagoon.

Biosphere Reserve

  • Upper Gulf of California and Colorado River Delta Biosphere Reserve (RB) – includes the head of the Sea of Cortez with a southern limit between Punta San Felipe (Punta Macharro) and Punta Pelicano (Roca del Toro).

World distribution acronyms

World Distribution Acronyms are used by marine biologists to designate major habitat locations.

Acronyms used in chart

  • PET: Tropical Eastern Pacific; includes the whole Gulf of California; and the island groups of Lobos de Afuera and Lobos de Tierra; extends from the northern limit of the Bahía Magdalena lagoonal complex to northern Peru's Punta Aguja.
  • PNET: Temperate Northeastern Pacific; extends from the Gulf of California temperate waters north of Bahía Magdalena; to the Gulf of Alaska and southwest of the eastern Aleutian Islands.
  • PSET: Temperate Southeastern Pacific; includes the temperate waters south of Peruvian Punta Aguja and Lobos de Tierra to Tierra del Fuego (Cape Horn).
  • IGAL: Galapagos Islands, Ecuador.
  • IMAL: Malpelo Island, Columbia.
  • ICOC: Cocos Island, Costa Rica.
  • IREV: Revillagigedos Islands, Costa Rica; includes Islas Socorro, Clarion, San Benedicto, and Roca Partida.
  • ILTM: Islas Marías; Gulf of California - México; Islas Marías includes: Islas María Madre, María Magdalena, María Cleofas, and San Juanito.
  • IGUA: Guadalupe Island, Gulf of California - México.
  • RALI: Rocas Alijos, Gulf of California - México.
  • ENGC: Endemic to the Gulf of California.
  • PC: Central Pacific; includes the Pacific Plate west of the Eastern Pacific.
  • OI: Indian Ocean.
  • AW: Western Atlantic; includes the Atlantic Ocean west of the Mid-Atlantic Rise.
  • ART: Arctic Ocean.
  • CT: Circumtropical; includes the tropic oceans with occasional branches of distribution into temperate waters.

Chart of Northern Gulf sea urchins, heart urchins, and sand dollars

Blue urchin and blue seastar
Diadema mexicanum
Expl2777 Strongylocentrotus fragilis
Allocentrotus fragilis
Unknown Sand dollar 1 Macro
Encope grandis
Mellita longifissa
Mellita longifissa
Species of sea urchins, heart urchins, and sand dollars in the Northern Gulf of California, using the #World distribution acronyms for locations:
Scientific Name: Biogeographic Distribution: Depth Range (meters): World Distribution:
Agassizia scrobiculata GCN, GCC, GCS, SWB, RB 0 - 220 PET, IGAL
Allocentrotus fragilis GCN, GCC, GCS 50 - 1,200 PET, PNET
Aporocidaris milleri GCN, CCC, GCS, SWB 300 - 3,937 PET, ART, ANT, IMAL, IGAL
Arbacia incisa GCN, GCC, GCS, RB, SWB 0 - 52 PET, PNET, PSET, IGAL
Astropyga pulvinata GCN, GCC, GCS, SWB 0 - 90 PET, IREV, ILTM, IGAL, ICOC
Brisaster latifrons GCN, GCC, GCS, RB 9 - 2,817 PET, PNET, IGAL, ILTM
Brissopsis columbaris GCN, GCC, GCS 899 - 1,271 PET
Brissopsis pacifica GCN, GCC, GCS, SWB 9 - 2,379 PET, PNET, OI, PC, IREV, IGAL, ICOC
Brissus obesus GCN, GCC, GCS, RB, SWB 0 - 240 PET, IGAL, IGUA, PNET, RALI
Centrostephanus coronatus GCN, GCC, GCS, SWB, RB 0 - 125 PET, PNET, IGAL, ICOC
Clypeaster europacificus GCN, GCC, GCS 0 - 401 PET, IREV, ICOC, IGAL
Clypeaster ochrus GCN, GCC, GCS, RB 0 - 162 PET, IREV, ILTM, IGAL, ICOC
Clypeaster rotundus GCN, GCC, GCS, RB, SWB 0 - 91 PET, IREV, ILTM, ICOC, IGAL
Clypeaster speciosus GCN, GCC, RB, SWB 0 - 128 PET, IGAL, IREV, ICOC
Diadema mexicanum GCN, GCC, GCS, RB 0 - 113 PET, PNET, IGAL, ICOC, IMAL, ILTM, IREV
Echinometra oblonga GCN, GCC, GCS 0 - 34 PET, IREV, IGAL, PW, OI
Echinometra vanbrunti GCN, GCC, GCS, RB, SWB 0 - 106 PET, PNET, PSET, IGAL, ICOC, IREV, ILTM
Encope grandis GCN, GCC, GCS, RB, SWB 0 - 128 PET, AW
Encope micropora GCN, GCC, GCS, RB, SWB 0 - 120 PET, PNET, PSET, IREV, IGAL, ICOC
Encope perspectiva GCN, GCC, GCS 15 - 27 PET, PNET, IGAL
Eucidaris thouarsii GCN, GCC, GCS, RB, SWB 0 - 150 PET, PNET, IREV, ILTM, IGAL, ICOC, IMAL, IGAL
Hesperocidaris asteriscus GCN, GCC, GCS 2 - 183 PET, IREV
Hesperocidaris perplexa GCN, GCC, GCS 13 - 1,500 PET, IREV, PNET
Lovenia cordiformis GCN, GCC, GCS, RB, SWB 0 - 201 PET, PNET, IREV, ICOC, IGAL, PC
Lytechinus pictus GCN, GCC, GCS, RB, SWB 0 - 300 PET, PNET, ICOC, IGUA
Mellita grantii GCN, GCC, GCS, RB 0 - 6 ENGC
Mellita longifissa GCN, GCC, GCS, RB, SWB 0 - 60 PET, PNET
Meoma grandis GCN, GCC, GCS, SWB 0 - 200 PET, IREV, ICOC, IGAL
Metalia nobilis GCN, GCC, GCS, RB 0 - 18 PET
Moira atropos GCN, GCC, GCS, RB 0 - 160 PET, PNET
Nacospatangus depressus GCN, GCC 5 - 302 PET, PNET
Plagiobrissus pacificus GCN, GCC, GCS 6 - 137 PET, ICOC
Spatangus californicus GCN, GCC, GCS 10 - 644 PET, PNET
Strongylocentrotus purpuratus GCN, GCC 0 - 161 PET, PNET, IGUA
Tripneustes gratilla GCN, GCC, GCS 0 - 73 CT, PET, IREV, IGAL, IMAL

The scientific names, biogeographic distributions, world distributions, and depth ranges found in the list above are from the Sea of Cortez Database.

A study from 2005 adds the following species : Lytechinus anamesus, Toxopneustes roseus, Cassidulus pacificus, Mellita kanakoffi, Encope wetmorei, Brissus latecarinatus, Metalia spatagus, Brisaster townsendi, Moira clotho.

Summary of urchins of the Northern Gulf of California

  • 35 species of echinoids (100%) occur in the Northern Gulf of California (GNC).
  • 3 species (8.57%) are found in the Northern Gulf (GNC), Central Gulf (GCC), and outside of the Gulf, but are absent from the Southern Gulf.
  • 32 species (91.43%) are found throughout the Gulf (GNC, GCC, GCS).
  • 15 (42.86%) reside in the Southwest Baja California Sur Region (SBC) as well as in the Northern Gulf (GNC).
  • 1 species (2.86%) is endemic to the Gulf of California (Mellita grantii).
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