sea urchin

American  

noun

1. any echinoderm of the class Echinoidea, having a somewhat globular or discoid form, and a shell composed of many calcareous plates covered with projecting spines.

2. a tall evergreen shrub or small tree, Hakea laurina, of Australia, having narrow leaves and dense, globe-shaped clusters of crimson flowers with long yellow stamens.

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sea urchin British  

noun

1. any echinoderm of the class Echinoidea, such as Echinus esculentus ( edible sea urchin ), typically having a globular body enclosed in a rigid spiny test and occurring in shallow marine waters

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Etymology

Origin of sea urchin

First recorded in 1585–95

Example Sentences

When sea urchin populations grow too large, however, especially if their natural predators are heavily hunted or overfished, the balance can flip.

From Science Daily • Dec. 12, 2025

Yama Seafood Uni – The first time I tried uni — sea urchin — was at Shiro’s in Seattle.

From Salon • Dec. 4, 2025

Visitors to Puglia, a major producer of durum wheat, can try handmade pastas in a variety of shapes, paired with broccoli rabe, sea urchin and even a horse ragù.

From The Wall Street Journal • Oct. 27, 2025

Ninety-five percent of Northern California’s kelp forest has been displaced by sea urchin “barrens” since the West Coast’s marine heat wave in 2014, ’15 and ’16, when water temperature averaged 7 degrees above normal.

From Los Angeles Times • Jun. 5, 2024

Thicknesse had fallen to the ground with tiny spikes erupting all over him; he seemed to be turning into some form of sea urchin.

From "Harry Potter and the Deathly Hallows" by J.K. Rowling