Echinoid

Echinoid

Taxonomy

Phylum: Echinodermata

Class: Echinoidea

Diagnostic features

Ambulacra (tube feet)

Periproct (opening for anus)

Peristome (opening for mouth)

Pentaradial symmetry (regular echinoids)

Bilateral symmetry imposed upon pentaradial symmetry (irregular echinoids)

Stratigraphic range

Ordovician to Present (Irregular Echinoids from Jurassic to Present)

Way of life

Regular echinoids:

Grazers with functional jaw apparatus

Long spines for protection and movement

Epifaunal at a wide range of depths

Use tube feet for respiration and movement

Irregular echinoids:

Feed on organic matter in sediment, front shaped to funnel sediment into mouth

Use fine spines to move

Infaunal burrowers

Use tube feet for respiration

Advanced notes

Grazing echinoids leave a distinctive pentagonal feeding trace Gnathicnus pentax.

Learn about types of preservation

Specimens

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