Echinoderm

Red sea urchin

Mesocentrotus franciscanus

Rocky reefs, low tidepools, and kelp forests

Photo: (c) Rachel Crane, some rights reserved (CC BY) · CC-BY · Source and license. Displayed as a resized crop. Photograph illustrates the species.

Habitat: Rocky reefs, low tidepools, and kelp forests
Published depth range: Low intertidal to about 100 m; reported maxima differ among references
Viewing activities: Scuba diving · Beach / tidepool

What to look for

Long spines and a large body, colored brick red through dark burgundy.

What it eats

Algae, including drifting kelp.

Wider distribution

Alaska to Cedros Island, Baja California.

When to look

The available records do not establish a reliable local viewing season. Use the map’s month filter to inspect dated observations; it does not predict an encounter.

RECORDED PRESENCE

Where has Red sea urchin been recorded?

These destination links use the same area and date cutoff as the map: 40 km circles, except for the four named regional rectangles. Checked 2026-09-19. Counts describe source records, not individual animals or sighting odds.

Channel IslandsCalifornia, United States40 km radius · 69992 source records since 2016About this destination →La JollaCalifornia, United States40 km radius · 1842 source records since 2016About this destination →Monterey BayCalifornia, United StatesRegional rectangle · 153292 source records since 2016About this destination →

Sources, search boundaries and limitations