science education resource

For K-12 Students • Educators • Homeschool Families • Naturalists

Sea Urchin (Red)

To view these resources with no ads please Login or Subscribe (and help support our site).

Strongylocentrotus franciscanus
Sea Urchin (Red)


They are found from Alaska to Mexico and in Japan.


They live in rocky areas along coastal waters near their food source, kelp beds.

Body Traits

They are the largest sea urchin in their range, reaching about 8 inches (20 cm) across. Their spines are reddish and up to 3 inches long (7 cm). Underneath, they have a mouth for feeding and rows of tube feet on which to move along the ocean floor.


They gather in large groups near kelp beds.


They eat seaweeds (kelp) and small ocean creatures (invertebrates).


Sea otter eat them.

To view these resources with no ads, please Login or Subscribe (and help support our site).


Females release eggs into the water and males release sperms into the water (broadcasting) where fertilization takes place. Small swimming larvae hatch and grow over time into adult urchins.

Sea Urchin (Red)


Kingdom: Animalia
Phylum: Echinodermata
Class:  Echinoidea
Subclass: Euechinoidea
Superorder: Echinacea
Order:  Echinoida
Family: Strongylocentrotidae
Genus:  Strongylocentrotus
Species: S. franciscanus

Citing Research References

When you research information you must cite the reference. Citing for websites is different from citing from books, magazines and periodicals. The style of citing shown here is from the MLA Style Citations (Modern Language Association).

When citing a WEBSITE the general format is as follows.
Author Last Name, First Name(s). "Title: Subtitle of Part of Web Page, if appropriate." Title: Subtitle: Section of Page if appropriate. Sponsoring/Publishing Agency, If Given. Additional significant descriptive information. Date of Electronic Publication or other Date, such as Last Updated. Day Month Year of access < URL >.

Here is an example of citing this page:

Amsel, Sheri. "Sea Urchin (Red)" Exploring Nature Educational Resource ©2005-2023. March 26, 2023
< > has more than 2,000 illustrated animals. Read about them, color them, label them, learn to draw them.