Echinidae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of sea urchin

Sea urchin

Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...

s in the order Echinoida

Echinoida

Echinoida is an order of sea urchins in the class Echinoidea. They are distinguished from other sea urchins by simultaneously possessing both an un-sculpted test and a feeding lantern with large plates fused across the top of each pyramid.-Taxonomy:...

. Members of the family are found in the 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 the Antarctic

Antarctic

The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...

.

Characteristics

Members of the Echinidae family are characterized by having trigeminate ambulacra (quadrigeminate in one genus) with pairs of tube feet

Tube feet

Tube feet are the many small tubular projections found most famously on the oral face of a sea star's arms, but are characteristic of the water vascular system of the echinoderm phylum which also includes sea urchins, sand dollars and sea cucumbers and many other sea creatures.Tube feet function in...

 pores arranged either as vertical arcs or as a dense band. The ambulacral plates are compound. The tubercles are imperforate and do not have crenulate edges. There are few tubercles on the interambulacral plates. The buccal notches are reduced in size and, their most significant distinguishing feature, the pedicellariae

Pedicellariae

A pedicellaria is a small wrench or claw-shaped structure commonly found on Echinoderms, particularly in sea stars and sea urchins...

 are globiferous and have one or two pairs of lateral teeth on the narrow tubular blades.

Genera

According to the World Register of Marine Species

World Register of Marine Species

The World Register of Marine Species is a database that hopes to provide an authoritative and comprehensive list of names of marine organisms. The content of the registry is edited and maintained by scientific specialists on each group of organism. These taxonomists control the quality of the...

 (WoRMS), the following genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 are included in the family:

• Dermechinus - Mortensen, 1942
• Echinus
  Echinus (sea urchin)
  Echinus is a genus of sea urchins.-Species:Species in this genus include:* Echinus acutus de Lamarck, 1816* Echinus affinis Mortensen, 1903* Echinus alexandri Danielssen & Koren, 1883* Echinus elegans Düben & Koren, 1846...
  
  - Linnaeus, 1758
• Gracilechinus - Fell & Pawson, in Moore, 1966
• Polyechinus - Mortensen, 1942
• Sterechinus - Koehler, 1901
• Stirechinus - Desor, 1856 †